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This chapter contains procedures for configuring the Cisco uBR7200 series universal broadband routers using the Cisco command-line interface (CLI). For detailed descriptions of the commands used, refer to the Cisco IOS Multiservice Applications Command Reference publication.
This chapter includes the following sections:
Cisco uBR7200 series universal broadband routers are Data-over-Cable Service Interface Specifications (DOCSIS)-based cable modem termination systems (CMTSs) that typically serve as interfaces between a WAN backbone and a hybrid fiber-coaxial (HFC) cable network. Installed at a Community Antenna Television (CATV) head-end facility or distribution hub, the Cisco uBR7200 series is often located with the following Internet service provider (ISP)-related components:
The Ethernet switch is used to reduce traffic on the WAN backbone.
The proxy server usually functions as a Web cache for host computers and as the Dynamic Host Control Protocol/Trivial File Transfer Protocol (DHCP/TFTP) server for cable modems. DHCP for host computers in the HFC plant is often handled over the WAN. The WAN router provides a gateway to the data network.
For more information on these components and their requirements, refer to the "Supported System Configurations" section of the "Cisco uBR7200 Series Overview" chapter of the Cisco uBR7200 Series Hardware Installation Guide.
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Note At the time of publication of this document, the Cisco uBR7200 series universal broadband routers use 6 MHz radio frequency (RF) channel plans only. However, Cisco IOS Release 12.1 T will support 8 MHz channel plans with the Cisco MC16E cable modem card. |
On the RF side, the downstream port on the Cisco uBR7200 series router is assigned a 6 MHz channel slot at a standard broadcast CATV frequency. An upconverter device is used to convert the 44 MHz intermediate frequency (IF) output to the assigned slot. In North America, carrier frequencies in the forward plant are assigned from 54 MHz to 860 MHz. After upconversion, the signal is combined with other analog TV or digital TV signals and sent to the transmit input of a fiber transceiver.
The receive input of the fiber transceiver is connected to an upstream port of the Cisco uBR7200 series router. The upstream port is assigned a 0.2 MHz to 3.2 MHz frequency band in the reverse plant. In North America, carrier frequencies in the reverse plant are between 5 MHz and 42 MHz.
The fiber transceiver is connected to up to 80 kilometers of optical fiber. Signals are carried in analog form to a neighborhood, where they terminate in a fiber node. The fiber node, located on a telephone pole or in an underground box, converts the optical signal back to an electrical signal, which is then passed on to a two-way distribution amplifier system. The distribution amplifier system passes through the neighborhood, where it is tapped off to individual CATV subscribers.
A coaxial cable delivers the signal from the tap to a drop box located on the subscriber premises. From the drop box, the signal is split and cabled to consumer CATV appliances. One cable goes to the television or set-top box; the other cable goes to a cable modem appliance such as a Cisco uBR900 series cable access router, providing data and IP telephony services.
Figure 107 illustrates the topology of a typical HFC network supporting basic data services.
Cisco uBR7200 series routers support the DOCSIS 1.0 specifications (and static multiple service identifiers (SIDs) for voice) for the following high-speed data-over-cable interfaces:
Cisco cable modem cards residing in the Cisco uBR7200 series routers provide the interface between the protocol control information (PCI) bus on the router and the RF signal on the HFC network. The subscriber-end cable modems and Cisco cable access routers are connected to the HFC network through upconverters and the Cisco cable modem cards.
The Cisco uBR7200 series routers support a variety of cable modem cards with different upstream and downstream transmission capabilities and features. You must install at least one Cisco cable modem card in the Cisco uBR7200 series chassis to establish communication between the Cisco uBR7200 series and the HFC network. For detailed information, refer to the Cisco uBR7200 Series Universal Broadband Router Hardware Installation Guide.
Figure 108 shows a typical two-way configuration involving Voice over IP (VoIP) telephony services. The Cisco uBR7200 series supports the transmission of digitized voice and facsimile traffic over the cable and IP backbone network.
The Cisco uBR7200 series equipment and DOCSIS-based cable modems supporting IP telephony can be configured to treat VoIP and regular data traffic separately. The system can be configured to keep regular data on a default class of service, while using a higher priority for the VoIP traffic that originates on the VoIP ports of the cable modem.
When creating a configuration for remote cable modems, the Cisco uBR7200 series system administrator typically configures extra classes of service. These secondary classes of service are expected to be higher QoS classes that are used by higher priority traffic such as voice. These classes have a minimum upstream rate specified for the channel.
System administrators can associate unique packet flows with a unique SID. These images support multiple SIDs per cable modem.
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Note The cable modem must also support these higher classes of service. |
Cisco uBR7200 series routers can register third-party DOCSIS-based telco return cable modems based on the DOCSIS telco return specification. This feature enables the HFC network to support both two-way and telco return cable modems.
In telco return configurations, the Cisco uBR7200 series router provides downstream dataflow from cable modem cards connected to the cable system and accepts upstream traffic via a combination of the local public switched telephone network (PSTN) and IP network path that terminates at the Cisco uBR7200 series input/output (I/O) controller or applicable port adapter. Upstream data is through a telephone modem typically connected to an analog telephone line. (The telephone modem can be external or internal to a cable modem, or a cable modem card in a PC, based on the third-party cable modem vendor.) Telco return gives cable companies that have not upgraded their cable plants or specific service areas to support two-way RF transmission the ability to offer fast downstream data services via the cable plant and upstream transmission via the PSTN.
Figure 109 illustrates a telco return application.
Downstream traffic must be precluded by Telephony Channel Descriptor (TCD) messages to enable upstream telco return traffic. TCD messages contain information necessary for the telco return cable modem to access the headend/ISP network access server (for example, a Cisco AS5300 or Cisco AS5800) over the PSTN.
TCD packets contain three critical telco return elements:
When connected, the network access server feeds the subscriber username and password to a RADIUS dial security server. Access is granted or denied. When access has been attained, the network server sets up a PPP negotiation and connection.
The Cisco uBR7200 series universal broadband routers support QoS as defined by the DOCSIS 1.0 specification. Service class profiles can be configured through the Cisco CLI to support the QoS profile number, traffic priority, maximum upstream bandwidth, guaranteed upstream bandwidth, maximum downstream bandwidth, maximum transmit burst length, baseline privacy enable/disable, and type of service (ToS) overwrite byte.
The QoS Profile Enforcement feature allows you to control the QoS to eliminate any interference from improper local-rate limiting implemented on the cable modem. The CMTS provisions a registering cable modem with a default DOCSIS 1.0 service class assigned by the operator, overriding any service class that previously existed on the modem. This service class has no upstream or downstream rate limits so that the CMTS can do traffic shaping based on the QoS profile enforced by the operator.
As part of this functionality, Cisco uBR7200 series routers support multiple service classes per cable modem by providing multiple static QoS service identifiers (SIDs). The multiple SIDs feature allows the Cisco uBR7200 series CMTS to dynamically allocate and delete service flows for voice and fax transmissions.
These features are described in more detail in the following sections. For additional information on QoS, refer to the Cisco IOS Quality of Service Solutions Configuration Guide.
Cisco uBR7200 series routers allow you to create multiple service class profiles with the following characteristics:
Using these service class profiles, you can define the following:
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Note Most of the time, these queues will be empty because bandwidth requests get served immediately in MAPs. |
The Cisco uBR7200 series routers allow you to statically define multiple service IDs (SIDs) on the upstream, enabling multiple service classes per cable modem. Multiple SIDs allow you to specify priority service flows higher than those specified in DOCSIS 1.0.
Multiple SIDs provide the following functionality:
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Note Reliable operation with voice requires multiple SIDs---at least two per cable modem to separate voice from data traffic. In DOCSIS 1.0, SIDs are set up statically. In DOCSIS 1.1, SIDs can be set up either statically or dynamically. |
When this feature is enabled, the CMTS provisions each registering cable modem with a default DOCSIS 1.0 service class that is assigned by the CMTS operator. The operator-defined service class is enforced on cable modems attempting to register with the CMTS regardless of the provisioned class of service. The default service class has no upstream or downstream rate limits.
When the cable modem sends data upstream, it makes bandwidth requests without throttling or dropping packets because of its own rate-policing algorithm. The CMTS does traffic shaping based on the QoS profile enforced by the operator.
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Note By default, the system will not enforce a specific QoS profile on the cable modem. The QoS profile assigned to the cable modem will depend on the class of service parameters provisioned in the DOCSIS configuration file. |
Tag switching is a Cisco-developed technology that implements a next-generation architecture for the Internet backbone and large intranets. Tags placed on the fronts of packets contain forwarding information used for making switching decisions and applying network services.
Tag switching has become the foundation for flexible Layer 3 virtual private networks (VPNs), QoS handling, and traffic engineering. It also forms the basis for the emerging Internet Engineering Task Force (IETF) standard for Multiprotocol Label Switching (MPLS).
A tag switching infrastructure combines with advanced routing protocol capabilities to define IP VPNs by selectively advertising IP reachability information to just those subscribers within the same VPN or extranet, thus keeping different VPN traffic logically separate. The subscribers are then all connected via tag switch paths (TSPs).
Forwarding is based entirely upon the assigned tag values (rather than IP destination prefixes), eliminating the requirement for uniqueness in the IP addresses that are used. This feature means subscribers to different VPNs need not concern themselves with the problems that would otherwise occur when connecting networks with different subnetworks into an integrated network.
NetFlow switching is a high-performance, network-layer switching path that provides network administrators with access to "call detail recording" information from their data networks; this information includes details such as user, protocol, port, ToS information, and the duration of the communication. This data can be used for a variety of purposes, including billing, enterprise accounting, network planning and performance analysis, QoS bandwidth management, security policies, and data warehousing/mining for marketing purposes.
The collected NetFlow data is sent out via UDP packets to a workstation running the Netflow Flowcollector server, which can collect data from multiple routers for later analysis by a user running the Netflow Flowanalyzer application. Through the NetFlow Data Export feature, traffic information can also be passed to external applications that perform functions such as billing or network performance analysis.
NetFlow also provides a highly efficient mechanism that can process security access lists without incurring the same performance penalty as other available switching methods. In conventional switching at the network layer, each incoming packet is handled on an individual basis with a series of functions to perform access list checks, capture accounting data, and switch the packet. In contrast, after NetFlow switching identifies a flow and processes the access list for the first packet of the flow, all subsequent packets are handled on a "connection-oriented" basis as part of the flow. This process avoids further access list checks on the flow, and packet switching and statistics capture are performed in tandem.
Weighted Random Early Detection (WRED) enables you to specify traffic handling policies to maximize throughput under congestion conditions. Random early detection (RED) works in conjunction with TCP to intelligently avoid network congestion. WRED combines IP precedence and RED capabilities to provide differentiated performance characteristics for different classes of service, thus providing preferential traffic handling for higher priority traffic. You can define minimum and maximum queue depth thresholds and drop probabilities for each class of service.
For more information on this feature, refer to the Cisco IOS Quality of Service Solutions Configuration Guide.
Weighted Fair Queueing (WFQ) performs priority output queueing and custom queueing to grant resources to important sessions when network bandwidth is saturated; it is typically used for digitized voice packets to help reduce delay. WFQ provides expeditious handling for high priority traffic, requiring low delay, while fairly sharing the remaining bandwidth between lower priority traffic. WFQ divides link traffic into high and low priority flows based on metrics including IP precedence and traffic volume.
For more information on this feature, refer to the Cisco IOS Quality of Service Solutions Configuration Guide.
Resource Reservation Protocol (RSVP) works in conjunction with WFQ; it helps the router establish a weight for different types of packets that affect the order in which the packets enter the output queue and are placed on the cable network for transmission. Voice packets are routed through the interface with a QoS method that allows the packets to receive priority over standard data frames. A router that supports RSVP gives priority to packets that fall into a reservation within RSVP.
For more information on this feature, refer to the Cisco IOS Quality of Service Solutions Configuration Guide.
Committed Access Rate (CAR) provides the means to allocate and limit bandwidth to traffic sources and destinations, and specify policies to handle traffic exceeding the bandwidth allocation. CAR policies can be utilized at the ingress or egress of the network. CAR uses token bucket filters to measure traffic load and limit sources to bandwidth allocations.
The following sections describe features that enhance the security of devices attached to the Cisco uBR7200 series cable access routers.
The Cisco uBR7200 series routers support DOCSIS baseline privacy (BPI). When BPI is enabled, the Cisco uBR7200 series generates Traffic Encryption Keys (TEKs) for each applicable SID. The router uses the keys to encrypt downstream data and decrypt upstream traffic from two-way cable modems.
The Cisco uBR7200 series supports both 40-bit and 56-bit encryption/decryption. When BPI is enabled, 56-bit encryption/decryption is the default. A configuration command allows an administrator to manually force the Cisco uBR7200 series to generate a 40-bit DES key, where the DES key that is generated and returned masks the first 16 bits of the 56-bit key to 0 in software.
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Note Both the Cisco uBR7200 series universal broadband router and the cable modem must contain software and be configured to support encryption/decryption. |
The Cisco uBR7200 series router generates keys for unicast, broadcast, and multicast operation as appropriate. Keys are refreshed periodically and have a default lifetime of 12 hours.
As an enhancement to baseline privacy, Cisco uBR7200 series universal broadband routers can be configured for cable modem and multicast authentication using the RADIUS protocol, an access server authentication, authorization, and accounting (AAA) protocol originally developed by Livingston, Inc. The Cisco uBR7200 series also supports additional vendor-proprietary RADIUS attributes.
When a cable modem comes online or when an access request is sent through a multicast data stream, the Cisco uBR7200 series sends relevant information to RADIUS servers for cable modem/host authentication. This feature can be configured on a per-interface basis.
An IETF draft standard, RFC 2138, defines the RADIUS protocol. RFC 2139 defines the corresponding RADIUS accounting protocol. Additional RFC drafts define vendor-proprietary attributes and MIBs that can be used with a Simple Network Management Protocol (SNMP) manager.
Upstream address verification prevents the spoofing of IP addresses by comparing the source IP address with the MAC address of the cable modem, thus verifying that each upstream data packet comes from the cable modem known to be associated with the source IP address in the packet. The cable source-verify [dhcp] cable interface command specifies that DHCP lease query requests are sent to verify any unknown source IP address found in upstream data packets. This feature requires a DHCP server that supports the LEASEQUERY message type.
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Note Cisco Network Registrar (CNR) supports the LEASEQUERY message type in software release 3.01(T) and later. |
Traffic shaping is a Cisco patent-pending feature that conserves bandwidth by reducing the chances that information will be retransmitted to hosts on the HFC network. Traffic shaping in the upstream direction delays the scheduling of the upstream packet, causing the packet to be buffered on the cable CPE device instead of being dropped. Traffic shaping allows the TCP/IP stack to pace the application traffic appropriately and approach throughput commensurate with the QoS levels defined for the subscriber.
Without traffic shaping, the Cisco uBR7200 series software drops bandwidth requests from cable modems that are found to have exceeded their configured peak upstream transmission rate. Dropping bandwidth requests (and eventually upstream packets) from a rate-exceeding cable modem causes TCP-related timeouts which cause the host sending the information to resend its information. Retransmitted information wastes bandwidth on the network.
The Cisco uBR7200 series supports the following traffic shaping features:
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Note Packets that contain ToS bytes that have not been configured for downstream data rates continue to use the common data rate limits. |
The following sections describe operational and provisioning features and enhancements of the Cisco uBR7200 series cable access routers.
The dynamic ranging feature is a Cisco patent-pending feature that supports quick restoration of service following a catastrophic plant failure. With dynamic ranging, hundreds of cable modems can come back online quickly. The time that the cable modems spend deferring contention ranging slots is minimized, significantly reducing cable modem reinitialization time.
Downstream channel ID configuration allows all cable modems on the HFC network to identify themselves via unique downstream channel IDs instead of their downstream frequencies. Cable modems communicate their downstream ID when making a connection, not their downstream frequency. This feature allows system administrators to enter a configurable downstream channel ID to a value other than the default. Thus, each downstream channel ID can be unique on a cable network.
Cisco uBR7200 series routers are able to change the downstream frequency for any or all cable modems, overriding the DOCSIS configuration file settings.
Cisco uBR7200 series routers can report and limit the number of CPE devices per cable modem using CLI commands or SNMP.
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Note This feature is separate from the ability of a cable modem to support multiple CPE devices. For example, depending on the Cisco IOS software release being used, Cisco uBR900 series cable access routers can support a maximum of either 3 or 254 CPE devices. Also, by default, a DOCSIS-based cable modem supports one CPE device, but this can be changed by modifying the MAX CPE parameter in the DOCSIS configuration file. |
For each modulation/burst profile configuration, Cisco uBR7200 series universal broadband routers will support burst profile number, burst profile interval usage code, burst type, preamble length and unique word length, differential encoding enable/disable, forward error correction (FEC) correctable bytes value, FEC code word length, scrambler seed value, maximum burst size, guard time size, last code word shortened/lengthened, and scrambler enable/disable.
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Note Multiple burst profiles are supported on the MC11C, MC12C, MC14C, MC16B, and MC16C cable modem cards. Only one profile is supported on the original MC11-FPGA card. |
The Cisco uBR7200 series cable access routers can manipulate the GIADDR field of DHCPDISCOVER and DHCPREQUEST packets with a Relay IP address before they are forwarded to the DHCP server.
By modifying the GIADDR field based on whether the source is a cable modem or a host, the Cisco uBR7200 series provides hints to the DHCP server as to where (that is, on which IP subnet) the server should allocate addresses to the requesting client.
Per-modem and per-host access lists allow Cisco uBR7200 series routers to filter incoming packets from individual hosts or cable modems based on the source MAC or IP address. Access lists can thus be specified on a per-interface or a per-address basis. The packets received from cable modems or individual hosts are filtered based on the cable modem or host from which the packets are received.
You can preconfigure the filters by using the CLI following standard Cisco IOS access list and access group configuration procedures. You can assign these filters to a user or modem by using the CLI or SNMP.
This feature also supports traps to inform the CMTS about the online/offline status of modems.
Cisco uBR7200 series routers provide support for a basic wiretap facility for VoIP calls, as required by the United States Federal Communications Assistance for Law Enforcement Act (CALEA). The wiretap facility is based on the MAC address of the cable modem, so it can be used for either data or digitized voice connections.
The feature is controlled by the cable intercept command, which requires a MAC address, an IP address, and a UDP port number as its parameters. When activated, the Cisco uBR7200 series universal broadband router examines each packet for the desired MAC address; when a matching MAC address is found (for either the origination or destination endpoint), a copy of the packet is encapsulated into a UDP packet, which is then sent to the specified server at the given IP address and port.
Inter-Switch Link (ISL) is a Cisco protocol used to interconnect multiple routers and switches and maintain virtual LAN (VLAN) information as traffic passes between routers and switches.
Cisco uBR7200 series routers are able to obtain the correct time-of-day (ToD) and respond to (RFC 868) queries from cable modems during the registration process.
Cisco uBR7200 series routers offer an integrated DHCP server to simplify the provisioning of cable modems.
We recommend that system administrators use upstream frequency hopping as a countermeasure to long-term narrowband noise. To provide this capability, Cisco uBR7200 series routers contain a spectrum manager that continuously monitors the noise in unused upstream channels. If the CNR reaches an unacceptable level on a particular channel, the spectrum manager will automatically assign a new upstream channel to the cable modem using that channel. This is referred to as frequency agility.
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Note Frequency hopping is not effective against broadband noise phenomena such as impulse noise. |
The Cisco uBR7200 series allows you to create up to 32 cable spectrum groups, each containing multiple upstream ports. The configured channel width is used for each upstream. In addition, the router maintains a flap list containing the MAC address for each cable modem having problems maintaining its connection. (A "flapping modem" is a cable modem that rapidly disconnects and reconnects to the CMTS.)
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Note Because spectrum management capabilities focus on the upstream path over an HFC network, this feature is not applicable to one-way (telco return) systems. |
Before you can configure Cisco uBR7200 series universal broadband router features, you must first perform the following tasks:
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Note The combiner refers to all cables, amplifiers, and taps at the headend or cable distribution center that connect the Cisco uBR7200 series to the HFC network. |
The Cisco IOS software CLI is used to configure the Cisco cable modem card for correct operation on the HFC network. To configure the Cisco cable modem card, perform the tasks described in the following sections. For some tasks, the default values are adequate to configure the device; these configuration tasks are optional.
The first step in configuring the Cisco cable modem interface is to configure the downstream cable interface. The downstream direction refers to the data flow from the Cisco cable modem card in a Cisco uBR7200 series to the subscriber's cable modem. Data passing through the Cisco cable modem card is converted to IF and then passed through an upconverter to transform the signal to RF. This RF signal is then sent down the line to the subscriber's cable modem. Downstream cable interface commands configure the frequency, symbol rate, compression, and modulation of the downstream signal.
To configure the downstream cable interface, perform the following tasks:
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Note In most applications, the default values for the commands used in these configuration steps are adequate to configure the Cisco uBR7200 series router. |
| Command | Purpose | |
|---|---|---|
Step 1 |
| Enters enable (privileged EXEC) mode. Enters the password. You have entered privileged EXEC mode when the prompt displays the pound symbol ( |
Step2 |
| Enters global configuration mode. You have entered global configuration mode when the prompt displays This command can be abbreviated to config t. |
Step3 |
| Enters cable interface configuration mode. In this example, the interface is downstream port0 on the cablemodem card installed in slot6 of the CiscouBR7200 series. |
Step4 |
| Default. Activates downstream digital data from the CiscouBR7200 series. |
Step5 | | Places the downstream port in the "admin up" state. |
Step6 |
| Returns to privileged EXEC mode. |
To verify whether or not the downstream carrier is active (up), enter the show controllers cable command for the downstream port that you just configured:
CMTS01# show controllers cable 6/0 downstream
Cable6/0 Downstream is up
Frequency=96000000, Channel Width 6 MHz, 64-QAM, Symbol Rate 5.056941 Msps
FEC ITU-T J.83 Annex B, R/S Interleave I=32, J=4
To troubleshoot the configuration, perform the following tasks:
Downstream frequency is an information-only parameter that must match the digital carrier frequency, which is the center frequency of the downstream RF carrier (the channel) for a particular downstream port. The configuration controlling the digital carrier frequency is performed in the IF-to-RF upconverter that must be installed in the downstream path from the Cisco uBR7200 series. Refer to the documentation for your upconverter for information about configuring the upconverter.
Enter the fixed center frequency of the downstream RF carrier for the downstream port. You can also select a default that does not set a specific fixed value. The valid range for a fixed center frequency is 54,000,000 to 1,020,000,000Hz.
The digital carrier frequency is specified to be the center of a 6.0 MHz channel. For example, EIA channel 95 spans 90.000 to 96.000 MHz. The center frequency is 93.000 MHz, which is the digital carrier frequency that should be configured as the downstream frequency. The typical range for current CATV headends is 88,000,000 to 860,000,000Hz. The DOCSIS specification is 91,000,000 to 857,000,000Hz:
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NoteThe digital carrier frequency is not the same as the video carrier frequency. For EIA channel95, the video carrier frequency is 91.250 MHz, which is 1.75 MHz below the center frequency. |
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NoteThis command currently has no effect on external upconverters; it is informational only. |
| Command | Purpose |
|---|---|
| Sets the fixed center frequency for your downstream RF carrier in Hz. |
To verify the current value of the center frequency, enter the show controllers cable command for the downstream port that you have just configured.
router#show controllers cable 6/0 downstream Cable6/0 Downstream is up Frequency=96000000, Channel Width 6 MHz, 64-QAM, Symbol Rate 5.056941 Msps FEC ITU-T J.83 Annex B, R/S Interleave I=32, J=4
router# show controllers cable 6/0 downstream
Cable6/0 Downstream is up
Frequency is not set. Channel Width 6 MHz, 64-QAM, Symbol Rate 5.056941 Msps
FEC ITU-T J.83 Annex B, R/S Interleave I=32, J=4
To troubleshoot the configuration, perform the following tasks:
| Command | Purpose |
|---|---|
| Specifies the downstream channel ID. Acceptable range is 0 to 255. |
To verify the downstream channel ID, enter the show controllers cable command for the downstream port you have just configured:
CMTS01# show controllers cable 6/0 downstream
Cable6/0 Downstream is up
Frequency=96000000, Channel Width 6 MHz, 64-QAM, Symbol Rate 5.056941 Msps
FEC ITU-T J.83 Annex B, R/S Interleave I=32, J=4
To troubleshoot the configuration, perform the following tasks:
In Cisco IOS Release 12.1, only the AnnexB MPEG framing format is supported.
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NoteThe cable modem card downstream ports and the cable modems on the HFC network connected through these ports must be set to the same MPEG framing format. |
| Command | Purpose |
|---|---|
| Sets the downstream MPEG framing format. |
To verify the downstream MPEG framing format setting, enter the show controllers cable command for the downstream port you have just configured:
router# show controllers cable 6/0 downstream
Cable6/0 Downstream is up
Frequency=96000000, Channel Width 6 MHz, 64-QAM, Symbol Rate 5.056941 Msps
FEC ITU-T J.83 Annex B, R/S Interleave I=32, J=4
To troubleshoot the configuration, perform the following tasks:
The valid modulation rates for a downstream port on a Cisco cablemodem card are 64 QAM (6bits per downstream symbol rate) and 256 QAM (8bits per downstream symbol rate).
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NoteSetting a downstream modulation rate of 256-QAM requires approximately a 6dB higher signal-to-noise ratio (SNR) than 64-QAM at the subscriber cablemodem. If your network is marginal or unreliable at 256-QAM, use the 64-QAM format instead. |
To set the downstream modulation, use the following command in cable interface configuration mode:
| Command | Purpose |
|---|---|
| Sets the downstream modulation. The standard DOCSIS modulation rate (and the Cisco default) is 64qam. |
To verify the downstream modulation setting, enter the show controllers cable command for the downstream port you have just configured:
router# show controllers cable 6/0 downstream
Cable6/0 Downstream is up
Frequency=96000000, Channel Width 6 MHz, 64-QAM, Symbol Rate 5.056941 Msps
FEC ITU-T J.83 Annex B, R/S Interleave I=32, J=4
To troubleshoot the configuration, perform the following tasks:
Set the interleave depth for the downstream port on the Cisco cable modem card. A higher interleave depth provides more protection from bursts of noise on the HFC network; however, it will increase downstream latency. The valid values are 8, 16, 32 (default), 64, and 128.
| Command | Purpose |
|---|---|
| Sets the downstream interleave depth in milliseconds. |
To verify the downstream interleave depth setting, enter the show controllers cable command for the downstream port you have just configured:
router# show controllers cable 6/0 downstream
Cable6/0 Downstream is up
Frequency=96000000, Channel Width 6 MHz, 64-QAM, Symbol Rate 5.056941 Msps
FEC ITU-T J.83 Annex B, R/S Interleave I=32, J=4
To troubleshoot the configuration, perform the following tasks:
Specify an IP address of a DHCP server where UDP broadcast (DHCP) packets will be sent. You can specify a DHCP server for UDP broadcast packets from cablemodems and a DHCP server for UDP broadcast packets from hosts.
| Command | Purpose | |||
|---|---|---|---|---|
Step1 |
| Sets the downstream helper address to the DHCP server at IP address 10.x.x.x for UDP broadcast packets from cablemodems.
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Step2 | | Sets the downstream helper address to the DHCP server at IP address 172.56.x.x for UDP broadcast packets from hosts. |
To verify the downstream helper address setting, enter the show running-config command and look for ip helper-address in the cable interface configuration information:
CMTS01# show running-config Building configuration... Current configuration: ! interface Cable4/0 ip address 10.254.254.254 255.0.0.0 no ip directed-broadcast ip helper-address 192.168.1.1 no keepalive
To troubleshoot the configuration, perform the following tasks:
Downstream rate limiting enables you to use the token bucket policing algorithm with traffic shaping options or the weighted discard policing algorithm to buffer, shape, or discard packets that exceed a set bandwidth. Downstream rate limiting is disabled by default.
| Command | Purpose | |
|---|---|---|
Step1 |
| Enables rate limiting on the downstream port using the token bucket policing algorithm. With this command, the Cisco uBR7200 series will automatically drop packets in violation of the allowable bandwidth. |
Step2 | | Enables rate limiting on the downstream port using the weighted packet discard policing algorithm and assign a weight for exponential moving average of loss rate. Acceptable values are 1 to 4. |
Step3 |
| Exits to EXEC mode so that you can verify the steps. |
To verify whether or not downstream rate limiting has been configured and activated, enter the show running-config command and look for the cable interface configuration information. If downstream rate limiting has been configured and enabled, a rate limiting entry will be displayed in the output; if downstream rate limiting is disabled, no rate limiting entry will be displayed.
CMTS01# show running-config Building configuration... Current configuration: ! interface Cable4/0 ip address 10.254.254.254 255.0.0.0 no ip directed-broadcast ip helper-address 192.168.1.1 no keepalive cable downstream rate-limit token-bucket shaping cable downstream annex B cable downstream modulation 64qam
To troubleshoot the configuration, perform the following tasks:
The upstream direction refers to the data flow from a subscriber cable modem to the cable modem card in a Cisco uBR7200 series router. The subscriber cable modem sends an RF signal back to the Cisco cable modem card, which translates the RF signal back to data format. Upstream cable interface commands configure the frequency and input power level of the upstream signal, in addition to error detection and correction of the upstream signal.
The configuration of the upstream cable interface depends on the characteristics of the cable operator's physical plant.
To configure the upstream cable interface, perform the following tasks:
The upstream channel frequency of your RF output must be set to comply with the expected input frequency of your Cisco cable modem card. To configure upstream channel frequencies, you may configure a fixed frequency of 5 to 42 MHz and enable the upstream port, or create a global spectrum group, assign the interface to it, and enable the upstream port.
You can also select a default that does not set a specific fixed value.
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NoteSome cable systems cannot reliably transport frequencies near the edges of the 5 to 42 MHz band. The wider the upstream channel (in MHz), the more difficulty you could have. Enter a center frequency of 20 to 38 MHz if you are having difficulty. |
The cablemodem card receiver accepts time-division multiplexed burst transmissions from cablemodems that are DOCSIS compliant. The upstream port becomes "up" when it is assigned an upstream frequency and is configured to be administratively up.
The upstream port is frequency-agile. The frequency can change while the interface is up and carrying traffic, if you define spectrum groups. See the "Configuring and Activating Frequency Agility" section later in this chapter for details.
Upstream burst parameters can be configured by defining individual modulation profiles. A modulation profile consists of a table of physical layer characteristics for the different types of upstream bursts; for example, initial maintenance, long grant, request/data, request, short grant, and station maintenance.
|
NoteThe upstream cable interface will not operate until you either set a fixed upstream frequency or create and configure a spectrum group. See the "Configuring and Activating Frequency Agility" later in this chapter for details. If you are setting a fixed upstream frequency, make sure that the frequency selected does not interfere with the frequencies used for any other upstream applications running in the cable plant. |
|
NoteIf you are using the first version of the MC11 cablemodem card, you cannot define an alternative upstream modulation profile. |
To set a fixed upstream frequency, use the following commands in cable interface configuration mode:
| Command | Purpose | |
|---|---|---|
Step1 |
| Sets a fixed upstream frequency when you enter the fixed center frequency for your upstream RF carrier in Hz. Valid range for usport is from 0 to 5 if you are using the MC16 cable modem card. |
Step2 |
| Places the upstream port in the "admin up" state. |
To configure the default upstream frequency (which is no fixed frequency), enter the cable upstream usport frequency command without specifying a center frequency.
To verify the current value of the upstream frequency, enter the show controllers cable command for the upstream port you have just configured:
CMTS01# show controllers cable 6/0 u0
Cable6/0 Upstream 0 is up
Frequency 24.016 MHz, Channel Width 1.600 MHz, QPSK Symbol Rate 1.280 Msps
Spectrum Group is overridden
SNR 33.2560 dB
Nominal Input Power Level 0 dBmV, Tx Timing Offset 2288
Ranging Backoff automatic (Start 0, End 3)
Ranging Insertion Interval automatic (60 ms)
Tx Backoff Start 0, Tx Backoff End 4
Modulation Profile Group 1
|
NoteThe upstream frequency displayed in the show controllers cable command output might not match the frequency that you entered when you set the upstream frequency. The Cisco uBR7200 series might select an upstream frequency close to the frequency you entered that offers better performance. The minimum upstream frequency step size on the MC16C is 32 kHz. The CiscouBR7200 series selects the closest frequency available. |
To troubleshoot the configuration, perform the following tasks:
Enter the channel width in Hz. Valid values are 200000 Hz (160 kilosymbols per second, or ksps), 400000 Hz (320ksps), 800000 Hz (640ksps), 1600000 Hz (1280ksps), and 3200000 Hz (2560ksps). The default is 1600000Hz.
|
NoteIf you change the channel width, the symbol rate changes accordingly (symbol rate = 1.25 * channel width). Higher symbol rates are more susceptible to RF noise and interference. If you use a symbol rate or modulation format beyond the capabilities of your HFC network, you might experience packet loss or loss of cablemodem connectivity. |
|
NoteFor QAM-16 channel widths of 400 kHz (320 ksps) or greater, we recommend that you use 16-QAM modulation only for long and short data and that you use QPSK for request, initial, and station communication. For QAM-16 channel widths of 200 kHz (160 ksps), all communication must be able to use 16-QAM. That is, 160 ksps with 16-QAM requires an exceptional SNR in your upstream channel(s). When you use QAM-16 for request, initial, and station maintenance messages with channel widths greater than 400 kHz, the QAM-16 preamble and message data takes longer to transmit than the QPSK format. |
To set the upstream channel width, use the following command in cable interface configuration mode:
| Command | Purpose | |
|---|---|---|
Step1 |
| Sets the upstream channel width for your upstream RF carrier in Hz. |
Step2 |
| Returns the channel width to its default setting of 1600000 Hz. |
To verify the current value of the upstream channel width, enter the show controllers cable command for the upstream port you just configured:
CMTS01# show controllers cable 6/0 u0
Cable6/0 Upstream 0 is up
Frequency 24.016 MHz, Channel Width 0.800 MHz, QPSK Symbol Rate 0.640 Msps
Spectrum Group is overridden
SNR 33.2560 dB
Nominal Input Power Level 0 dBmV, Tx Timing Offset 2288
Ranging Backoff automatic (Start 0, End 3)
Ranging Insertion Interval automatic (60 ms)
Tx Backoff Start 0, Tx Backoff End 4
Modulation Profile Group 1
To troubleshoot the configuration, perform the following tasks:
The Cisco uBR7200 series controls the output power levels of the cable modems to meet the desired upstream input power level. The nominal input power level for the upstream RF carrier is specified in decibels per millivolt (dBmV). The default setting of 0dBmV is the optimal setting for the upstream power level.
The valid range for the input power level depends on the data rate. At 1.6 MHz, the valid range is -10dBmV to 25dBmV. If your power levels operate at greater than the maximum valid level, you must use an inline attenuator to bring the power level to within the valid range.
 |
CautionIf you increase the input power level, the cable modems on your HFC network will increase their transmit power level. A higher power level increases the CNR on the network but also increases distortion products. Composite Second Order Beat (CSO) and Composite Triple Beat (CTB) values worsen by 2 dB for every 1 dB of increased CNR. The return path laser immediately enters a nonlinear mode called clipping and all communication is no longer reliable. Many return lasers send short bursts well above the clipping thresholds and fail on longer or successive bursts. |
You should not adjust your input power level by more than 5dB in a 30-second interval. If you increase the power level by more than 5dB within 30seconds, cablemodem service on your network will be disrupted. If you decrease the power level by more than 5dB within 30seconds, cablemodems on your network will be forced offline.
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NoteWe recommend that the adjacent channel not have a large variation when you enter the cable upstream 0 power-level command. The recommended maximum input power variance is 5 to 6dBmV. |
| Command | Purpose |
|---|---|
| Sets the upstream input power level. Enter the upstream power level in dBmV. Default = 0 dBmV. |
To verify the current value of the upstream input power level, enter the show controllers cable command for the upstream port you have just configured:
CMTS01# show controllers cable 6/0 u0
Cable6/0 Upstream 0 is up
Frequency 24.016 MHz, Channel Width 0.800 MHz, QPSK Symbol Rate 0.640 Msps
Spectrum Group is overridden
SNR 33.2560 dB
Nominal Input Power Level 0 dBmV, Tx Timing Offset 2288
Ranging Backoff automatic (Start 0, End 3)
Ranging Insertion Interval automatic (60 ms)
Tx Backoff Start 0, Tx Backoff End 4
Modulation Profile Group 1
To troubleshoot the configuration, perform the following tasks:
The admission control is set as a percentage of the specified upstream channel capacity. The acceptable range is from 10 to 1000 percent. Admission control is disabled by default.
| Command | Purpose |
|---|---|
| Sets the admission control as a percentage of the upstream channel capacity. Valid range is from 10 to 1000 percent. |
To verify whether or not upstream admission control has been configured and activated, enter the show running-config command in privileged EXEC mode and look for the cable interface configuration information. If upstream admission control has been configured and enabled, an admission control entry will be displayed in the show running-config output, indicating the user-defined percentage of upstream channel capacity allowable. If upstream admission control is disabled, no admission control entry will be displayed in the output.
CMTS01# show running-config
To troubleshoot the configuration, perform the following tasks:
The CiscouBR7200 series uses forward error correction (FEC) to attempt to correct any upstream data that might have been corrupted. FEC is activated by default and should not be disabled. When FEC is activated, all cable modems on the network also activate FEC.
|
NoteAlthough upstream FEC is an option, we recommend that you always leave it activated. |
| Command | Purpose |
|---|---|
CMTS01(config-if)# cable upstream usport fec | Enables FEC. This is the default setting. |
To verify if FEC is activated or deactivated, enter the more system:running-config command and look for the cable interface configuration information. If FEC is enabled, an FEC entry will be displayed in the show running-config output. If FEC is disabled, no FEC entry will be displayed in the output. The following is an excerpt from the more system:running-config command output.
router# more system:running-config
Building configuration...
!
interface Cable6/0
ip address 1.1.1.1 255.255.255.0
no keepalive
cable insertion-interval 150000
cable downstream annex B
cable downstream modulation 64qam
cable downstream interleave-depth 32
cable downstream symbol-rate 5056941
cable upstream 0 frequency 15008000
cable upstream 0 fec
cable upstream 0 scrambler
no cable upstream 0 shutdown
To troubleshoot the configuration, perform the following tasks:
| Command | Purpose |
|---|---|
CMTS01(config-if)# cable upstream usport minislot-size size | Specifies the minislot size in ticks for the selected upstream interface. Acceptable values are 2, 4, 8, 16, 32, 64, and 128. |
To verify upstream minislot size, enter the show controllers cable 6/0 u0 command for the upstream port you have just configured:
CMTS01# show controllers cable 6/0 u0
Cable6/0 Upstream 0 is up
Frequency 24.016 MHz, Channel Width 1.600 MHz, QPSK Symbol Rate 1.280 Msps
Spectrum Group is overridden
SNR 33.2560 dB
Nominal Input Power Level 0 dBmV, Tx Timing Offset 2288
Ranging Backoff automatic (Start 0, End 3)
Ranging Insertion Interval automatic (60 ms)
Tx Backoff Start 0, Tx Backoff End 4
Modulation Profile Group 1
part_id=0xFFFF, rev_id=0xFF, rev2_id=0xFF
nb_agc_thr=0x0000, nb_agc_nom=0x0000
Range Load Reg Size=0x58
Request Load Reg Size=0x0E
Minislot Size in number of Timebase Ticks is = 8
Minislot Size in Symbols = 64
Bandwidth Requests = 0xFE
Piggyback Requests = 0xD
Invalid BW Requests= 0x2
Minislots Requested= 0x2963
Minislots Granted = 0x2963
Minislot Size in Bytes = 16
Map Advance = 4000 usecs
UCD Count = 32964
DES Ctrl Reg#0 = C000C043, Reg#1 = 0
To troubleshoot the configuration, perform the following tasks:
The scrambler on the upstream RF carrier enables cable modems on the HFC network to use built-in scrambler circuitry for upstream data transmissions. The scrambler circuitry improves reliability of the upstream receiver on the cable modem card. The upstream scrambler is activated by default and should not be disabled under normal circumstances.
|
CautionThe upstream scrambler must be activated for normal operation. Disabling it can result in corrupted packets. Disable it only for prototype modems that do not support scrambler. |
| Command | Purpose |
|---|---|
CMTS01(config-if)# cable upstream usport scrambler | Enables the scrambler. This is the default. |
To verify whether or not the upstream scrambler is activated, enter the more system:running-config command and look for the cable interface configuration information. The following is an excerpt from the more system:running-config command output:
CMTS01# more system:running-config
Building configuration...
Current configuration:
!
interface Cable6/0
ip address 1.1.1.1 255.255.255.0
no keepalive
cable insertion-interval 150000
cable downstream annex B
cable downstream modulation 64qam
cable downstream interleave-depth 32
cable downstream symbol-rate 5056941
cable upstream 0 frequency 15008000
cable upstream 0 fec
cable upstream 0 scrambler
no cable upstream 0 shutdown
To troubleshoot the configuration, perform the following tasks:
| Command | Purpose |
|---|---|
CMTS01(config-if)# cable upstream usport differential-encoding | Enables differential encoding. |
Upstream differential encoding is disabled by default.
To verify whether or not upstream differential encoding is activated, enter the show running-config command and look for the cable interface configuration information. If upstream differential encoding is enabled, a differential encoding entry will be displayed in the show running-config output. If upstream differential encoding is disabled, no differential encoding entry will be displayed in the output.
To troubleshoot the configuration, perform the following tasks:
Upstream rate limiting allows upstream bandwidth requests from rate-exceeding cable modems to be buffered without incurring TCP-related timeouts and retransmits. The CMTS can thus enforce the peak upstream rate for each cable modem without degrading overall TCP performance for the subscriber CPE devices. Upstream grant shaping is per cablemodem (SID).
Token bucket policing with shaping is the per-upstream default rate-limiting setting at the CMTS. Shaping can be enabled or disabled for the token bucket algorithm.
| Command | Purpose | |
|---|---|---|
Step1 | CMTS01(config-if)# cable upstream usport rate-limit | Enables rate limiting for the specified upstream cable interface. |
Step2 | CMTS01(config-if)#^Z CMTS01# | Exits to EXEC mode so that you can verify upstream rate limiting. |
To disable upstream traffic shaping for an upstream port, enter the following command in cable interface configuration mode:
CMTS01(config-if)# no cable upstream usport rate-limit
To verify whether or not upstream rate limiting has been configured and activated, enter the show running-config command and look for the cable interface configuration information. If upstream rate limiting has been configured and enabled, a rate limiting entry will be displayed in the show running-config output. If upstream rate limiting is disabled, no cable upstream rate-limit will be displayed in the output.
You can also perform the following tasks to verify that rate limiting is enabled on the upstream channel:
Step 2 Use a regular rate-limiting algorithm on the upstream without rate shaping and see the drops of the excess bandwidth requests from this cable modem when it exceeds its peak upstream rate.
Use the show interface cx/y sid counters command to see the bandwidth request drops. See that the upstream rate received by that modem is in fact less than its configured peak rate due to the timeouts and backoffs produced by the drop in bandwidth requests. To see the input rate at the CMTS in bps, enter the show interface cx/y sid command.
Step 3 Enable grant shaping on the upstream channel by using the new shaping keyword extension to the token bucket algorithm CLI command.
Step 4 Make the cable modem exceed its peak upstream rate by generating heavy upstream traffic and see the effect of grant buffering (shaping) at the CMTS. If you use cable modem-to-CMTS pings, you will notice the pings slowing down.
Let the pings run for a few minutes (to let averages at CMTS settle); then see the upstream rate received by this single modem. Use the show interface cx/y command and observe the input rate in bps. This value should be close to the modem's peak upstream rate. Also observe the drop counts for the modem's SID by using the show interface sid counters command and see that CMTS no longer drops the bandwidth requests from the cable modem.
The bandwidth request drop count (from previous nonshaping test) remains unchanged when upstream rate shaping is used, indicating that the CMTS is actually shaping (buffering) the grants for the modem. See that the input rate at the CMTS (from the single rate-exceeded cable modem) stabilizes close to the configured peak rate of 128 kbps.
To troubleshoot the configuration, perform the following tasks:
| Command | Purpose |
|---|---|
CMTS01(config-if)# cable upstream usport
frequency-adjust averaging percentage | Sets the minimum number of frequency adjustment packets required to justify changing the upstream frequency adjustment method as a percentage. Acceptable range is 10to 100 percent. Default = 30 percent. |
To return the automatic upstream frequency adjustment percentage to the default value of 30 percent, enter the following command in cable interface configuration mode:
CMTS01(config-if)# no cable upstream usport frequency-adjust averaging
To verify whether or not upstream frequency adjustment has been configured and activated, enter the show running-config command and look for the cable interface configuration information. If upstream frequency adjustment is enabled, frequency adjustment entries will be displayed in the show running-config output. If frequency adjustments have been disabled, no frequency adjustment entry will be displayed in the output.
To troubleshoot the configuration, perform the following tasks:
| Command | Purpose | |
|---|---|---|
Step1 | CMTS01(config-if)# cable upstream usport power-adjust continue db | Sets the minimum power adjustment in dB that will allow continued ranging status. Valid values are 2 to 15 dB. Default = 2 dB. |
Step2 | CMTS01(config-if)# cable upstream usport power-adjust noise percentage | Sets the minimum number (percentage) of power adjustment packets required to justify changing the upstream power rating. Valid values are 10 to 100percent. Default = 30 percent. |
Step3 | CMTS01(config-if)# cable upstream 0 power-adjust threshold db | Sets the power adjustment threshold in dB. Valid values are 0 to 2 dB. Default = 1 dB. |
Step4 | CMTS01(config-if)# end CMTS01# | Returns to enable (privileged EXEC) mode. |
To return the automatic upstream power adjustment ranging value to the default of 2 dB, enter the following command in cable interface configuration mode:
CMTS01(config-if)#nocable upstreamusportpower-adjust continue
To return the automatic upstream power adjustment noise value to the default of 30 percent, enter the following command in cable interface configuration mode:
CMTS01(config-if)#nocable upstreamusportpower-adjust noise
To return the upstream power adjustment threshold value to the default of 1 dB, enter the following command in cable interface configuration mode:
CMTS01(config-if)#nocable upstreamusportpower-adjust threshold
To verify whether or not upstream power adjustment has been configured and activated, enter the show running-config command and look for the cable interface configuration information. If upstream power adjustment is enabled, any or all three of the continue, noise, and threshold power adjustment entries will be displayed in the show running-config output. If all three continue, noise, and threshold upstream power adjustments have been disabled, no power adjustment entry will be displayed in the showrunning-config output.
To troubleshoot the configuration, perform the following tasks:
| Command | Purpose | |
|---|---|---|
Step1 | CMTS01(config-if)# cable upstream usport time-adjust continue seconds | Sets the minimum timing adjustment that will allow continued ranging status. Valid values are 2 to 64seconds. Default = 2 seconds. |
Step2 | CMTS01(config-if)# cable upstream usport time-adjust threshold seconds | Sets the timing adjustment threshold value in seconds. Valid values are 1 to 32 seconds. |
Step3 | CMTS01(config-if)# end m CMTS01# | Returns to enable (privileged EXEC) mode. |
To return the upstream time adjustment ranging value to the default of 2 seconds, enter the following command in cable interface configuration mode:
CMTS01(config-if)#no cable upstreamusporttime-adjust continue
To return the upstream time adjustment threshold value to the default of 1 second, enter the following command in cable interface configuration mode:
CMTS01(config-if)#no cable upstreamusporttime-adjust threshold
To verify whether or not upstream timing adjustment has been configured and activated, enter the show running-config command and look for the cable interface configuration information. If upstream timing adjustment is enabled, either or both of the continue and threshold timing adjustment entries will be displayed in the show running-config output. If both the continue and threshold upstream timing adjustments have been disabled, no timing adjustment entry will be displayed in the showrunning-config output.
To troubleshoot the configuration, perform the following tasks:
Each upstream port must be activated to enable upstream data transmission from the cable modems on the HFC network to the Cisco uBR7200 series router.
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NoteThe upstream cable interface will not operate until you either set a fixed upstream frequency or create and configure a spectrum group. See the "Set the Upstream Frequency" or the "Configuring and Activating Frequency Agility" sections in this chapter for details. |
To activate the upstream ports, use the following commands beginning in global configuration mode:
| Command | Purpose | |
|---|---|---|
Step1 | CMTS01(config)# interface cable slot/port | Specifies a cable interface and enters cable interface configuration mode. |
Step2 | CMTS01(config-if)# no cable upstream usport shutdown | Enables upstream data traffic. |
To verify whether the upstream ports are activated or deactivated, enter the show interface cable command for the upstream port that you have just configured:
router# show interface cable 6/0
Cable6/0 is up, line protocol is up
Hardware is BCM3210 FPGA, address is 00e0.1e5f.7a60 (bia 00e0.1e5f.7a60)
Internet address is 1.1.1.3/24
MTU 1500 bytes, BW 27000 Kbit, DLY 1000 usec, rely 255/255, load 1/255
Encapsulation, loopback not set, keepalive not set
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:00:25, output 00:00:00, output hang never
Last clearing of "show interface" counters never
Queueing strategy: fifo
Output queue 0/40, 0 drops; input queue 0/75, 0 drops
To troubleshoot the configuration, perform the following tasks:
The DOCSIS-specified method of contention resolution for cable modems wishing to transmit data or requests on the upstream channel is a truncated binary exponential backoff, with the initial backoff window and the maximum backoff window controlled by the CMTS. The CiscouBR7200 series router specifies backoff window values for both data and initial ranging, and sends these values downstream as part of the Bandwidth Allocation Map (MAP) MAC message. The values are configurable on the CiscouBR7200 series and are power-of-two values. For example, a value of 4 indicates a window from 0 to 15; a value of 10 indicates a window from 0 to 1023.
You can set fixed start and end values for data backoff on the upstream ports, or you can set the upstream ports for automatic data backoff. You have the same options for ranging backoff. For both backoff windows, the default start value is 0; the default end value is 4. Valid values are from 0 to 15.
| Command | Purpose | |
|---|---|---|
Step1 | CMTS01(config-if)# cable upstream usport data-backoff start end | The automatic setting is optimized for up to 250 cablemodems per upstream port. Set manual values for data backoff windows only when operating with more than 250 cablemodems per upstream port. |
Step2 | CMTS01(config-if)# cable upstream usport range start end | The automatic setting is optimized for up to 250 cablemodems per upstream port. Set manual values for ranging backoff windows only when operating with more than 250 cablemodems per upstream port. |
When considering whether or not to adjust backoff values, note the following:
|
NoteUpstream segments serving a relatively large number of cablemodems (for example, more than 1600 or so) may suffer recovery times greater than 10minutes. |
To verify backoff window settings, enter the show controllers cable 6/0 u0 command for the upstream port you have just configured:
CMTS01# show controllers cable 6/0 u0
Cable6/0 Upstream 0 is up
Frequency 24.016 MHz, Channel Width 1.600 MHz, QPSK Symbol Rate 1.280 Msps
Spectrum Group is overridden
SNR 33.2560 dB
Nominal Input Power Level 0 dBmV, Tx Timing Offset 2288
Ranging Backoff automatic (Start 0, End 3)
Ranging Insertion Interval automatic (60 ms)
Tx Backoff Start 0, Tx Backoff End 4
Modulation Profile Group 1
part_id=0x3137, rev_id=0x03, rev2_id=0xFF
nb_agc_thr=0x0000, nb_agc_nom=0x0000
Range Load Reg Size=0x58
Request Load Reg Size=0x0E
Minislot Size in number of Timebase Ticks is = 8
Minislot Size in Symbols = 64
Bandwidth Requests = 0xFE
Piggyback Requests = 0xD
Invalid BW Requests= 0x2
Minislots Requested= 0x2963
Minislots Granted = 0x2963
Minislot Size in Bytes = 16
Map Advance = 4000 usecs
UCD Count = 32964
DES Ctrl Reg#0 = C000C043, Reg#1 = 0
To troubleshoot the configuration, perform the following tasks:
To encrypt upstream and downstream data, you need to configure and activate baseline privacy. Baseline privacy on an HFC network is configured with key encryption keys (KEKs) and traffic encryption keys (TEKs). The encryption is based on 40-bit or 56-bit data encryption standard (DES) encryption algorithms.
A KEK is assigned to a cable modem based on the cable modem SID and permits the cable modem to connect to the CiscouBR7200 series when baseline privacy is activated. The TEK is assigned to a cable modem when its KEK has been established. The TEK is used to encrypt data traffic between the cable modem and the CiscouBR7200 series.
KEKs and TEKs can be set to expire based on a grace-time or a life-time value. A grace-time key is used to assign a temporary key to a cable modem to access the network. A life-time key is used to assign a more permanent key to a cable modem. Each cable modem that has a life-time key assigned will request a new life-time key from the CiscouBR7200 series before the current one expires.
|
NoteBaseline privacy is only supported in Cisco IOS software containing "-k1" in the filename. If you do not already have a baseline privacy software image, you must download the software from Cisco Connection Online (CCO). |
|
NoteBaseline privacy will not operate unless the cablemodem configuration file specifies that privacy is on. |
The configuration and activation of baseline privacy depends on each cable operator physical plant.
To configure and activate baseline privacy, perform the following tasks:
A grace-time KEK can be set from 300 to 1800 seconds. A life-time KEK can be set from 86,400 to 6,048,000 seconds. If you do not set a KEK value, the default values are used.
| Command | Purpose |
|---|---|
| Sets the cable privacy KEK grace time in seconds. Valid values are from 300 to 1800 seconds. Default = 600. |
To verify the KEK life-time or grace-time values that have been set, enter the show cable privacy kek command:
CMTS01# show cable privacy kek
Configured KEK life time value = 750000
Configured KEK grace time value = 800
To troubleshoot the configuration, make sure you have entered a valid value for grace time or life time.
A grace-time TEK can be set from 300 to 1800 seconds. A life-time TEK can be set from 1800 to
604,800 seconds. If you do not set a TEK value, the defaults are used.
| Command | Purpose |
|---|---|
CMTS01(config-if)# cable privacy tek grace-time seconds | Sets the cable privacy TEK grace time in seconds. Valid values are from 300 to 1800 seconds. Default = 600. |
To verify the TEK life-time or grace-time values that have been set, enter the show cable privacy tek command:
CMTS01# show cable privacy tek
Configured TEK life time value = 56000
Configured TEK grace time value = 900
To troubleshoot the configuration, make sure you have entered a valid value for grace time or life time.
After the KEK and TEK values have been set, activate encryption on the HFC network by using the following commands in cable interface configuration mode:
| Command | Purpose | |
|---|---|---|
Step1 | CMTS01(config-if)# cable privacy enable | Activates cable privacy. This is the default. |
Step2 | CMTS01(config-if)# cable privacy mandatory | Activates cable privacy and does not allow access for any unencrypted cable modem connections. |
To verify whether or not baseline privacy is activated, enter the cable privacy enable or cable privacy mandatory command. By default, cable privacy is enabled and can only be disabled with the no cable privacy command.
To troubleshoot the configuration, perform the following tasks:
The Cisco uBR7200 series universal broadband routers divide a cable plant into downstream channels. Downstream channels contain upstream segments.
Each upstream segment typically serves more than one fiber node. Upstream segments can be defined as one of the following:
|
NoteA cablemodem card supports either sparse or dense segments---not both. |
Defining sparse segments allows the cable operator to share upstream bandwidth among fiber nodes with fewer subscribers. Defining dense segments allows the cable operator to provide larger upstream bandwidth to fibernodes with many subscribers. Figure 110 illustrates sparse versus dense segments.
As shown in Figure 110, the downstream segment can contain multiple upstream segments. Two fiber nodes can be in one downstream segment but in different upstream segments.
An upstream frequency has an associated upstream input power level in dBmV. Cable operators must make noise measurements and determine the cable plant spectrum management policy. Different modulation schemes and symbol rates can be used based on the characteristics of the cable plant and the cablemodem card contained in the Cisco uBR7200 series chassis. Bits are encoded into a two-dimensional mapping called a constellation. A good carrier-to-noise ratio is needed to properly decode symbols into bits.
The return path of several fiber nodes can be combined at a single point to form a single RF frequency domain called a combiner group. The CiscouBR7200 series software allows a frequency hop table called a spectrum group to be associated with a combiner group.
|
NoteA combiner group refers to an RF topology point. A spectrum group refers to the frequency hop table associated with a combiner group. |
The Cisco uBR7200 series routers support up to 32 spectrum groups. Each spectrum group defines the table of frequencies to be used in a specific frequency plan. Cisco cablemodem cards interface the downstream and upstream ports to the cable plant, while port adapters connect to the IP backbone and external networks.
Upstream port frequency should be set to a fixed value during system installation and testing. This value is chosen from the allocation plan for the RF domain for the RF plant segment connected to the upstream.
|
NoteHaving fixed frequency settings is recommended during early deployment at least until amplifier cascade adjustments or plant repair becomes infrequent for the nodes connected to the upstream port. When multiple upstream ports are combined to provide increased bandwidth, care should be taken to prevent overlapping frequency bands. |
When the system has reached sufficient stability, the RF domain topology can be entered into the CiscoIOS configuration file to enable RF spectrum management. This management feature---also called frequency agility---applies a common frequency management policy to a set of upstream ports.
Spectrum management or frequency agility is configured and activated using spectrum groups. A spectrum group is a frequency hop table that can be used by upstream ports to implement a frequency-hopping policy. There are four types of frequency-hopping policies: blind, scheduled, combined blind and scheduled, and guided.
|
NoteWhen each upstream port has its own RF domain, the group is called a nonshared spectrum group. When multiple upstream ports share the same RF domain, the group is called a shared spectrum group. |
|
NoteThe cable interface will not operate until you either create and configure a spectrum group or set a fixed upstream frequency. From the interface configuration prompt, an interface is assigned membership in a spectrum group. From the interface point of view, the spectrum group also represents the set of upstreams connected to the same group of fiber nodes. The spectrum manager is able to determine if upstream frequencies need to be managed together. |
In general, when defining your spectrum use the following guidelines:
Frequency agility is configured and activated using spectrum groups that are controlled by the spectrum manager. You can create from 1 to 32 spectrum groups for each Cisco uBR7200 series cablemodem card upstream port.
To configure and activate frequency agility, perform the tasks in the following sections:
Following is an example topology for a CiscouBR7223 with combiner groups designated A through J. Combiner groups C and E have multiple upstream ports that should be configured in a shared spectrum group. The other upstreams should be configured in a nonshared spectrum group.
In this example, ten combiner groups are served with frequency hop tables from three spectrum groups:
Cable3/0 DS +-----+ Upconverter +----- laser group 1 U0 +----- combiner group A U1 +----- combiner group B U2 +------combiner group C U3 +------combiner group C U4 +----- combiner group D U5 +------combiner group E Cable4/0 DS +-----+ Upconverter +----- laser group 2 U0 +------combiner group E U1 +----- combiner group F U2 +----- combiner group G U3 +----- combiner group H U4 +----- combiner group I U5 +----- combiner group J
The laser group term refers to the set of fiber nodes that share the same downstream signal. An optical splitter is often used to create individual feeds per node.
In the downstream direction, two 6 MHz channel slots are assigned. All fiber nodes in combiner groups A through E should have a channel slot containing the downstream signal from Cable3/0. Combiner groups A through E are said to belong to laser group 1.
All fiber nodes in combiner groups E through J should have a channel slot containing the downstream signal from Cable4/0. Combiner groups E through J are said to belong to laser group 2.
Because combiner group E belongs to two laser groups, there should be two different downstream channel slots for Cable3/0 and Cable4/0.
To create a spectrum group, use one of the following commands in global configuration mode:
| Command | Purpose |
|---|---|
CMTS01(config)# cable spectrum-group group-number type blind | Creates a blind spectrum group. |
To verify that a spectrum group has been created, enter the show cable spectrum-group command:
CMTS01# show cable spectrum-group spectrum-group 1 spectrum-group 2 spectrum-group 3
To troubleshoot the configuration, make sure you have entered a valid spectrum group number and type.
After you create a spectrum group, you need to configure a list of upstream frequencies and optional nominal power levels that each spectrum group can use when an upstream frequency change is necessary. Each spectrum group should have its own list of upstream frequencies. Valid frequencies are 5,000,000 to 42,000,000 Hz; valid power levels at a channel width of 1.6 MHz are -10dBmV to 25dBmV.
To configure and activate a spectrum group, use one of the following commands in global configuration mode:
| Command | Purpose | ||
|---|---|---|---|
CMTS01(config)# cable spectrum-group group-number [time day hh:mm:ss] [delete] frequency ctr-freq-hz [power-level-dbmv] | Adds the upstream frequency to the list of valid frequencies with a default power level for a spectrum group.
The power level value should only be changed if you want to change the power level as part of spectrum management. The standard power level is 0dBmV. |
|
NoteConfiguring a spectrum group enables frequency agility and disables the fixed upstream frequency setting. You must repeat the command described above for each frequency or power level that you want to add to a spectrum group's list of valid values. |
If your cable plant has an upstream noise characteristic on a weekly cycle, use time-scheduled spectrum allocation. An example follows:
CMTS01(config)# cable spectrum-group 1 time Mon 08:00:00 frequency 21600000
Deletion is performed using the delete keyword:
CMTS01(config)# cable spectrum-group 1 time Mon 18:00:00 delete frequency 21600000
The following is an example of a spectrum group configuration that is designed to perform minor equalization as a function of frequency.
CMTS01(config)# cable spectrum-group 1 frequency 21600000 CMTS01(config)# cable spectrum-group 1 frequency 24800000 1 CMTS01(config)# cable spectrum-group 1 frequency 28000000 2
In this example, the upstream port nominal receive power at 21.6 MHz is 0 dBmV, at 24.8 MHz is 1dBmV, and at 28.0 MHz is 2 dBmV. At any time, the power level set in the interface configuration overrides the spectrum group power level.
The following example enables spectrum management for all upstream ports, assuming that all combiner groups use the frequency band from 20 to 26 MHz:
CMTS01(config)# cable spectrum-group 1 band 20000000 26000000 CMTS01(config)# cable spectrum-group 2 shared CMTS01(config)# cable spectrum-group 2 band 20000000 26000000 CMTS01(config)# cable spectrum-group 3 shared CMTS01(config)# cable spectrum-group 3 band 20000000 26000000 CMTS01(config)# interface Cable3/0 CMTS01(config-if)# cable spectrum-group 1 CMTS01(config-if)# cable upstream 2 spectrum-group 2 CMTS01(config-if)# cable upstream 3 spectrum-group 2 CMTS01(config-if)# cable upstream 5 spectrum-group 3 CMTS01(config-if)# exit CMTS01(config)# interface Cable4/0 CMTS01(config-if)# cable spectrum-group 1 CMTS01(config-if)# cable upstream 0 spectrum-group 3
A description of the spectrum groups 1 through 3 follows:
Upstream Port RF Domain Cable3/0 U0 combiner group A Cable3/0 U1 combiner group B Cable3/0 U4 combiner group D Cable4/0 U1 combiner group F Cable4/0 U2 combiner group G Cable4/0 U3 combiner group H Cable4/0 U4 combiner group I Cable4/0 U5 combiner group J
Upstream Port RF Domain Cable3/0 U2 combiner group C Cable3/0 U3 combiner group C
Upstream Port RF Domain Cable3/0 U5 combiner group E Cable4/0 U0 combiner group E
For the 20 to 26 MHz band of each RF domain, the spectrum is channelized according to the channelwidth settings of each member port. For example, if the ports U2 and U3 of Cable3/0 are set to 3.2 MHz and 1.6 MHz channel widths, respectively, then spectrum group 2 uses the following channelization:
> Channel Width Start Stop Center > (Mhz) (Mhz) (Mhz) (Mhz) > 1 3.2 20.0 23.2 21.6 > 2* 1.6 20.0 21.6 20.8 > 3* 1.6 21.6 23.2 22.4 > 4 1.6 23.2 24.8 24.0
|
NoteChannels 2 and 3 are not available when channel 1 is in use. |
Because the group is shared, ports U2 and U3 will be assigned channels 1 and 4, respectively, to prevent overlap.
|
NoteThere are no alternate frequency assignments for either port and bandwidth is wasted from 24.8 to 26.0 MHz. To create alternate channels, increase the upper boundary from 26.0 to 28.0MHz. |
> Channel Width Start Stop Center > (Mhz) (Mhz) (Mhz) (Mhz) > 1 3.2 20.0 23.2 21.6 > 2 3.2 23.2 26.4 24.8 > 3 1.6 20.0 21.6 20.8 > 4 1.6 21.6 23.2 22.4 > 5 1.6 23.2 24.8 24.0 > 6 1.6 24.8 26.4 25.6 > 7 1.6 26.4 28.0 27.4
Care should be taken to reduce the spectrum allocation when used with small channel widths. Otherwise, there will be a large number of upstream channel slots.
For example, if the allocation is from 20.0 to 28.0 MHz and an upstream port has its channel width set to 0.2 MHz, then there will be 40 possible slots for that channel width. Blind frequency hopping may require several minutes to find the clean slot because it will try each available slot, one at a time for several seconds each try.
To verify if spectrum groups have been configured and activated, enter the show cable spectrum-group command:
CMTS01# show cable spectrum-group
22:07:46: %SYS-5-CONFIG_I: Configured from console by console
Group Frequency Upstream Weekly Scheduled Power Shared
No. Band Port Availability Level Spectrum
(Mhz) From Time: To Time: (dBmV)
1 5.000-15.000 0 Yes
1 12.000 0 Yes
1 22.000 7 Yes
2 29.000 6 No
2 26.000 0 No
3 35.000-41.000 0 No
3 16.000-19.000 5 No
5* 5.000-10.000 Thu 21:50:00 Thu 21:45:00 0 Yes
To verify frequency hopping on the Cisco uBR7200 series router, note the following:
After you have established basic operation, inject a tone to the upstream port. For example, if the upstream frequency is 22.4 MHz, inject a 22.4 MHz tone at approximately the same power level as the modem. (If the power level at the modem is 40 dBmV, set the tone power to 40dBmV.) The interfering carrier should shut down the channel and cause the frequency to change to the next configured value. In this example, the next configured value is 24.0 MHz.
If you do not have an RF tone generator, use another line card and modem that carries traffic. Connect the upstream to the same combiner group, and use the data carrier as an interfering signal by setting it to the same frequency. For example, to test frequency hopping on c3/0, install c4/0 and connect both upstreams together using a combiner. If the upstream frequency of c3/0 is 22.4 MHz, set c4/0 to 22.4 MHz while c4/0 is carrying traffic. This should force c3/0 to change the frequency to the next configured value.
To troubleshoot the configuration, make sure you entered a valid spectrum group number, time, frequency, and input power level. Also, when defining your spectrum, use the following guidelines:
Once you have created spectrum groups for your cable network, you can add characteristics to them, providing you with more definitive control over frequency usage and frequency hopping.
As stated in Section 6.3.2.2 of the DOCSIS RFI specification, RF channel migration occurs by broadcasting a change in the upstream channel descriptor (UCD) message to all cablemodems. The UCD message contains the upstream frequency and transmission parameters associated with an upstream channel.
The speed of channel migration via the UCD message is typically less than 20 ms. During this time, upstream transmission is interrupted until the cablemodem transmitter adjusts to its new frequency. Data is stored in the cablemodem buffers during this time and is sent when the frequency hop is complete.
Also, per the DOCSIS RFI, station maintenance intervals are used to perform per-modem "keepalive" polling. The Cisco uBR7200 series routers poll each cablemodem at a default rate of once every 10seconds. When ingress noise causes loss of keepalive messages from a configurable percentage of all cablemodems, resulting in those cable modems going offline, a new frequency is selected from the allocation table and a UCD update is performed.
The migration time is 10 seconds (maximum) for the decision and 20 ms for the frequency hop. The percentage threshold method prevents a single failing cablemodem from affecting service to other operational cablemodems. The system will not hop endlessly because one cablemodem is generating 90 percent of the errors and 90 percent of the traffic.
The minimum period between frequency hops is also configurable, with a default setting of 300 seconds. If the destination channel is expected to be impaired, the minimum period between frequency hops can be reduced to a small value such as 10 seconds. Reducing the time between frequency hops allows the frequency hop to continue more rapidly until a clear channel is found. If excessive frequency hop is a concern, the minimum period between hops can be increased.
| Command | Purpose | |
|---|---|---|
Step1 | CMTS01(config)# cable spectrum-group groupnum hop threshold percent | Sets the percentage of all cable modems losing keepalive messages (going offline) that will cause a frequency hop. |
Step2 | CMTS01(config)# cable spectrum-group groupnum hop period seconds | Sets the minimum time between frequency hops in seconds. Valid values are from 1 to 3600 seconds. |
The current implementation is known as blind frequency hop because there is no "look-ahead" mechanism. In this case, the search time is 0 seconds and the switching time is 20 ms.
| Command | Purpose |
|---|---|
CMTS01(config)# cable spectrum-group groupnum shared | Specifies a given spectrum group as "shared" and tells the CiscouBR7200 series that you want to be sure that upstream frequencies assigned to upstream interfaces are not assigned to additional upstream interfaces. |
To verify spectrum group characteristics and whether or not a spectrum group is shared, enter the show cable spectrum-group command:
CMTS01# show cable spectrum-group
22:07:46: %SYS-5-CONFIG_I: Configured from console by console
Group Frequency Upstream Weekly Scheduled Power Shared
No. Band Port Availability Level Spectrum
(Mhz) From Time: To Time: (dBmV)
1 5.000-15.000 0 Yes
1 12.000 0 Yes
1 22.000 7 Yes
2 29.000 6 No
2 26.000 0 No
3 35.000-41.000 0 No
3 16.000-19.000 5 No
5* 5.000-10.000 Thu 21:50:00 Thu 21:45:00 0 Yes
To troubleshoot the configuration, perform the following tasks:
To configure a frequency hop table after you have determined which upstream ports you want assigned to a combiner group, use the following commands:
| Command | Purpose | |
|---|---|---|
Step1 | CMTS01(config)# interface cable slot/port | Enters cable interface configuration mode for the interface to which you wish to assign a spectrum group. |
Step2 | CMTS01(config-if)# cable spectrum-group usport | Assigns the spectrum group to the interface. |
Step3 | CMTS01(config-if)# cable upstream number spectrum-group usport | Assigns the upstream ports to the spectrum group for the interface. |
Step4 | CMTS01(config-if)# no cable upstream slot/port shutdown | Places the upstream port in the "admin up" state. |
Step5 | CMTS01(config-if)# exitCMTS01# test cable hop c3/0CMTS01# test cable hop c3/0 | Exits configuration mode and forces the system to hop. |
To display the current allocation table and frequency assignments, use the show cable spectrum-group command.
Address Resolution Protocol (ARP) is an Internet protocol used to map IP addresses to MAC addresses on computers and other equipment installed in a network. You need to activate ARP requests on the cable interface so that the CiscouBR7200 series can perform IP address resolution on the downstream path.
|
NoteThe default values for the commands used in this configuration step are adequate in most cases to configure the Cisco uBR7200 series. |
To activate ARP requests, use the following command in cable interface configuration mode:
| Command | Purpose |
|---|---|
CMTS01(config-if)# cable arp | Enables ARP. This is the default. |
To verify whether or not cable ARP has been activated, enter the more system:running-config command and look for the cable interface configuration information. If ARP has been activated, it does not appear in this output. If ARP has been deactivated, it will appear in the output as no cable arp as shown in this command output excerpt:
CMTS01# more system:running-config
Building configuration...
Current configuration:
!
interface Cable6/0
ip address 1.1.1.1 255.255.255.0
no keepalive
no cable arp
cable insertion-interval 150000
cable downstream annex B
cable downstream modulation 64qam
cable downstream interleave-depth 32
cable downstream symbol-rate 5056941
cable upstream 0 frequency 15008000
cable upstream 0 fec
cable upstream 0 scrambler
no cable upstream 0 shutdown
To troubleshoot the configuration, make sure you entered the correct port and cable modem card slot number when you activated ARP and when you entered the show interface cable command.
Cable proxy ARP allows the CiscouBR7200 series to issue cable ARP requests on behalf of cable modems on the same cable network subnet.
|
NoteBecause the downstream and upstreams are separate interfaces, modems cannot directly perform ARP with other modems on the cable plant. |
|
NoteThe default values for the commands used in this configuration task are adequate in most cases to configure the Cisco uBR7200 series. |
To activate cable proxy ARP for host-to-host communications, use the following command in cable interface configuration mode:
| Command | Purpose |
|---|---|
CMTS01(config-if)# cable proxy-arp | Enables proxy ARP on the cable interface. This is the default. |
To verify whether or not cable proxy ARP has been activated or deactivated, enter the more system:running-config command and look for the cable interface configuration information. If cable proxy ARP has been activated, it does not appear in the output. If cable proxy ARP has been deactivated, it appears in the output as no cable proxy-arp as shown in this command output excerpt:
CMTS01# more system:running-config
Building configuration...
Current configuration:
!
interface Cable6/0
ip address 1.1.1.1 255.255.255.0
no keepalive
no cable proxy-arp
cable insertion-interval 150000
cable downstream annex B
cable downstream modulation 64qam
cable downstream interleave-depth 32
cable downstream symbol-rate 5056941
cable upstream 0 frequency 15008000
cable upstream 0 fec
cable upstream 0 scrambler
no cable upstream 0 shutdown
To troubleshoot the configuration, make sure you entered the correct port and cable modem card slot number when you activated cable proxy ARP.
The following sections describe configurable DHCP options for the Cisco uBR7200 series.
The cable relay agent is for use with DOCSIS-based DHCP servers that use option 87 to automatically map the Ethernet MAC address of a host (end user PC) with the cablemodem to which it is connected.
With the cable relay agent activated, the CiscouBR7200 series will insert the cablemodem MAC address into a DHCPpacket when a packet is received from a cablemodem or another host. The CiscouBR7200 series will then forward the packet to a DHCP server.
To activate the cable relay agent, use the following command in cable interface configuration mode:
| Command | Purpose |
|---|---|
CMTS01(config-if)# cable relay-agent-option | Activates the cable relay agent. This is the default. |
To troubleshoot the configuration, perform the following tasks:
Configure the CiscouBR7200 series so it will either assign primary addresses to both cablemodems and remote hosts, or assign primary addresses to cable modems and secondary addresses to remote hosts.
| Command | Purpose |
|---|---|
CMTS01(config-if)# cable dhcp-giaddr primary | Enables cable DHCP giaddr functionality so that primary addresses are assigned to both cable modems and remote hosts. |
To disable cable DHCP giaddr functionality (the default) after it has been enabled, enter the no cable dhcp-giaddr command in cable interface configuration mode.
To verify whether or not DHCP giaddr has been activated, enter the show running-config command and look for the cable interface configuration information. If DHCP giaddr has been activated, a notation will appear in this output. If DHCP giaddr has been deactivated, it will not appear in the output.
To troubleshoot the configuration, perform the following tasks:
The following sections describe configurable service options for the Cisco uBR7200 series.
To activate ToD service for the CiscouBR7200 series, use the following command in global configuration mode:
| Command | Purpose |
|---|---|
CMTS01(config)# cable time-server enable | Enables ToD service for the CiscouBR7200 series. |
To disable ToD service (the default) after it has been enabled, enter the no cable time-server command or the cable time-server disable command in global configuration mode.
To verify whether or not ToD service has been activated, enter the show running-config command and look for the global cable configuration information. If ToD service has been activated, an entry will appear in this output. If ToD service has been deactivated, no entry will appear in this output.
To troubleshoot the configuration, make sure you are in global configuration mode.
Additional IP parameters can be set to enable downstream echoing of upstream data. To configure these optional IP parameters, perform the tasks in the following sections:
|
NoteThe default values for the commands used in these configuration steps are adequate in most cases to configure the Cisco uBR7200 series. |
The CiscouBR7200 series echoes IP multicast packets by default. To activate IP multicast echo if it has been previously disabled, use the following command in cable interface configuration mode:
| Command | Purpose |
|---|---|
CMTS01(config-if)# cable ip-multicast-echo | Enables IP multicast echo. This is the default. |
To disable IP multicast echo, enter the no cable ip-multicast-echo command in cable interface configuration mode.
To verify whether IP multicast echo has been activated or deactivated, enter the more system:running-config command and look for the cable interface configuration information. If IP multicast echo is activated, there is no notation in the output as this is the default setting. If IP multicast echo has been deactivated, a notation appears in the output as shown in the following command output excerpt:
CMTS01# more system:running-config
Building configuration...
Current configuration:
!
interface Cable6/0
ip address 1.1.1.1 255.255.255.0
no keepalive
no cable ip-multicast-echo
cable insertion-interval 150000
cable downstream annex B
cable downstream modulation 64qam
cable downstream interleave-depth 32
cable downstream symbol-rate 5056941
cable upstream 0 frequency 15008000
cable upstream 0 fec
cable upstream 0 scrambler
no cable upstream 0 shutdown
To troubleshoot the configuration, make sure you entered the correct slot and port numbers when you entered cable interface configuration mode.
By default, the CiscouBR7200 series does not echo IP broadcast packets. To activate IP broadcast echo, use the following command in cable interface configuration mode:
| Command | Purpose |
|---|---|
CMTS01(config-if)# cable ip-broadcast-echo | Enables IP broadcast echo. |
To disable IP broadcast echo (the default setting), enter the no cable ip-broadcast-echo command in cable interface configuration mode.
To verify whether IP broadcast echo has been activated or deactivated, enter the more system:running-config command and look for a notation in the cable interface configuration information as shown in the following command output excerpt:
CMTS01# more system:running-config
Building configuration...
Current configuration:
!
interface Cable6/0
ip address 1.1.1.1 255.255.255.0
no keepalive
cable ip-broadcast-echo
cable insertion-interval 150000
cable downstream annex B
cable downstream modulation 64qam
cable downstream interleave-depth 32
cable downstream symbol-rate 5056941
cable upstream 0 frequency 15008000
cable upstream 0 fec
cable upstream 0 scrambler
no cable upstream 0 shutdown
To troubleshoot the configuration, make sure that you entered the correct slot and port numbers when you entered cable interface configuration mode.
The following sections describe optional cable profile configuration tasks:
This section describes how to define the elements that are used in a cable modulation profile. The CiscouBR7200 series router supports up to eight cablemodulation profiles. Profile 1 is the default.
|
CautionIf you change a cable modulation profile, you also make changes to the physical layer. Changing physical layer characteristics affects router performance and function; therefore, this task should only be performed by an expert. |
The following modulation profile values can be changed:
| Command | Purpose |
|---|---|
CMTS01(config)# cable modulation-profile profile iuc fec-tbytes fec-len burst-len guard-t mod scrambler seed diff pre-len last-cw uw-len | Creates a new cable modulation profile with a profile number of profile, or modifies the existing profile having the number profile. |
In the following example, the request burst for cable modulation profile 2 is defined to have 0fec-tbytes, 16 KB fec-len, a burst-len of 1, a guard time of 8, a mod value of qpsk, scrambler enabled with a seed value of 152, differential encoding disabled, a preamble length of 64 bits, a fixed code-word length, and 8-bit unique words for upstream unique word length.
CMTS01(config)# cable modulation-profile 2 request 0 16 1 8 qpsk scrambler 152 no-diff 64 fixed uw8
To remove a cable modulation profile, use the no cable modulation-profile profile command in global configuration mode. You can use this command to remove all modulation profiles except for modulation profile 1. Entering the no cable modulation-profile 1 command sets all of the parameters in profile 1 to the default values.
To verify whether or not a cable modulation profile has been created and to see how it is configured, enter the showcablemodulation-profile command:
CMTS01# show cable modulation-profileMo IUC Type Preamb Diff FEC err FEC Scrambl Max Guard Last Scrambl Preamb
length enco correct T seed B time CW offset
bytes size size short1 request qpsk 64 no 0x0 0x10 0x152 1 8 no yes 56
1 initial qpsk 128 no 0x5 0x22 0x152 0 48 no yes 0
1 station qpsk 128 no 0x5 0x22 0x152 0 48 no yes 0
1 short qpsk 72 no 0x5 0x4B 0x152 0 8 no yes 48
To troubleshoot the configuration, perform the following tasks:
The Cisco uBR7200 series router supports multiple QoS profiles. QoS profile1 is used during cablemodem registration; QoSprofile2 is the default QoS profile. Both of these profiles are preconfigured and cannot be removed. However, you can modify these profiles and create additional QoS profiles for various traffic flows.
| Command | Purpose | |
|---|---|---|
Step1 | CMTS01(config)# cable qos-profile groupnum | Creates a new QoS profile with a profile number of groupnum , or modifies an existing profile. |
Step2 | CMTS01(config)# cable qos-profile groupnum ip-precedence bits | Sets the bits in the ToS byte that enable you to configure individual data rate limits on a per-modem basis. Valid values are from 0 to 7. |
Step3 | CMTS01(config)# cable qos-profile groupnum guaranteed-upstream rate | Sets the guaranteed minimum upstream rate in kbps. Valid values are from 0 to 100000 kbps. Default = 0 (no reserved rate). |
Step4 | CMTS01(config)# cable qos-profile groupnum max-burst size | Sets the maximum upstream transmit burst size in bytes that the cable modem can send for any single transmit burst. Valid values are from 0 to 4080 bytes. Default = 0 (variable). Recommended max burst size = 1600. |
Step5 | CMTS01(config)# cable qos-profile groupnum max-upstream rate | Sets the maximum upstream data rate in kbps that a cable modem using this QoS profile will send. Valid values are from 0 to 100000 kbps. Default = 0 (no upstream rate limit.) |
Step6 | CMTS01(config)# cable qos-profile groupnum max-downstream rate | Sets the maximum downstream data rate in kbps that a cable modem using this QoS profile will receive. Valid values are from 0 to 100000 kbps. Default = 0 (no downstream rate limit.) |
Step7 | CMTS01(config)# cable qos-profile groupnum priority number | Assigns a relative priority number for the upstream traffic associated with this QoS profile. Valid values are from 0to7, with 7 being the highest priority. Default = 0. |
Step8 | CMTS01(config)# cable qos-profile groupnum tos-overwrite value | Overwrites the ToS byte in the IP datagrams received on the upstream before forwarding them downstream. Sets the mask bits to a hexadecimal value to help the CMTS identify datagrams for QoS on the backbone. |
|
NoteYou can use a single cable qos-profile command to configure multiple parameters for the selected QoS profile number. |
Use the no cable qos-profile groupnum command to remove an optional QoS profile, or in the case of QoS profiles 1 and 2, to return the parameters to their default values.
To verify whether or not a QoS profile has been created, and to see how it is configured, enter the show cable qos profile command:
CMTS01# show cable qos profile
Service Prio Max Guarantee Max Max tx TOS TOS Create B
class upstream upstream downstream burst mask value by priv
bandwidth bandwidth bandwidth enab
1 0 0 0 0 0 0x0 0x0 cmts no
2 0 64000 0 1000000 0 0x0 0x0 cmts no
3 0 1000 0 1000 0 0x0 0x0 cmts no
4 7 2000000 100000 4000000 0 0x0 0x0 cm yes
To troubleshoot the configuration, perform the following tasks:
The Cisco uBR7200 series router supports the creation of QoS table entries by SNMP or by cable modem registration requests. You can also configure the Cisco uBR7200 series to dynamically update QoS table entries via SNMP.
To set QoS table access, use one or more of the following commands in global configuration mode:
| Command | Purpose | |
|---|---|---|
Step1 | CMTS01(config)# cable qos permission create-snmp | Enables SNMP access to create entries in the QoS tables. |
Step2 | CMTS01(config)# cable qos permission update-snmp | Enables SNMP access to dynamically update entries in the QoS tables. |
Step3 | CMTS01(config)# cable qos permission modems | Enables QoS table entries to be created via cable modem registration requests. |
Step4 | CMTS01(config)# no cable qos permission | Disables both SNMP access and cable modem registration access to the QoS tables. |
To verify QoS permissions, enter the show cable qos permission command:
CMTS01# show cable qos permission Create by SNMP Update by SNMP Create by modems no no yes
To troubleshoot the configuration, perform the following tasks:
To override the provisioned QoS profile of the cable modems connecting to the Cisco uBR7200 series and enforce a CMTS-specified QoS profile, use the following command in global configuration mode:
| Command | Purpose |
|---|---|
CMTS01(config)# cable qos permission enforce index | Assigns the QoS profile, specified by the index number, to all cable modems attempting to connect to the CiscouBR7200 series. |
To verify a QoS profile assignment, perform the following steps:
Notice that the modems are getting their provisioned class of service as indicated by the show cable modem and show cable qos profile commands.
Step 2 Configure any QoS profile at the CMTS with a specific index number (for example, index1) by using the SNMP/CLI.
Step 3 Enter the cable qos permission enforce 1 global configuration command.
Step 4 Enter the clear cable modem all reset global configuration command to force the modems to reregister with the CMTS.
Notice that the cable modems are assigned temporarily the CMTS-defined PRE_REGISTRATION QoS profile with index 2 until the cable modems register with the CMTS.
Step 5 Use the debug cable reg command to see that the provisioned QoS parameters of the modems are overwritten at the CMTS during registration.
Notice that at the end of the registration, the modem gets the user-enforced QoS profile as indicated by the show cable modem and show cable qos profile commands.
For additional information, refer to the cable qos permission enforce command reference page in the Cisco IOS Multiservice Applications Command Reference.
You can manage the cable modems connected to the Cisco uBR7200 series on the HFC network by performing the optional tasks in the following sections:
|
NoteThe default values for the commands used in these configuration steps are adequate in most cases to configure the Cisco uBR7200 series. |
| Command | Purpose |
|---|---|
CMTS01(config-if)# cable sync-interval msec | Specify the interval in milliseconds (ms) between successive sync message transmissions from the CiscouBR7200 series. Valid values are from 1 to 200 ms. Default = 10 ms. |
To return the sync message interval to its default value of 10 ms, enter the no cable sync-interval command in cable interface configuration mode.
To verify whether or not a sync message interval has been configured, enter the show running-config command and look for the cable interface configuration information. If a sync message interval has been configured, it will appear in this output. If the sync message interval has been deactivated or reset to its default value, no sync interval command line will appear in the output.
To troubleshoot the configuration, perform the following tasks:
The Cisco uBR7200 series routers support both two-way communication and DOCSIS-based telco return communication from remote cable modems.
|
NoteDOCSIS telco return is only supported in Cisco IOS software containing "t" in the filename. If you do not have a software image that supports telco return, you will need to download the software from CCO. |
For detailed instructions on configuring telco return, refer to the document Telephone Return for the Cisco uBR7200 Series Cable Router on CCO. You will find this document on the index page for CiscoIOS software under the section "New Features for Cisco IOS Release 12.0(5)T".
The Cisco uBR7200 series can be configured to require all cable modems to return a known text string in order to register with the CMTS and gain access to the network. The text string can be from 1 to 80characters in length.
| Command | Purpose |
|---|---|
CMTS01(config-if)# cable shared-secret [0 | 7] authentication-key | Enables cable modem authentication. The number 0 specifies that an unencrypted authentication key follows; the number 7 specifies that an encrypted authentication key follows. |
To verify whether cable modem authentication has been activated or deactivated, enter the more system:running-config command and look for the cable interface configuration information. If cable modem authentication has been activated, it does not appear in this output. If cable modem authentication has been deactivated, it appears in this output as no cable secret-shared as shown in this command output excerpt:
CMTS01# more system:running-config
Building configuration...
Current configuration:
!
interface Cable6/0
ip address 1.1.1.1 255.255.255.0
no keepalive
no cable secret-shared
cable insertion-interval 150000
cable downstream annex B
cable downstream modulation 64qam
cable downstream interleave-depth 32
cable downstream symbol-rate 5056941
cable upstream 0 frequency 15008000
cable upstream 0 fec
cable upstream 0 scrambler
no cable upstream 0 shutdown
To troubleshoot the configuration, perform the following tasks:
|
NoteThe DOCSIS configuration file editor cannot reread the key from a completed file because it would violate the security design. |
Cable modem upstream address verification ensures that only known cable modems that have received DHCP leases through the Cisco uBR7200 series can access the HFC network. The CiscouBR7200 series will discard all packets received for or from hosts that have not received DHCP-assigned addresses.
| Command | Purpose |
|---|---|
CMTS01(config-if)# cable source-verify [dhcp] | Activates cable modem upstream verification. The dhcp option specifies that queries will be sent to verify unknown IP addresses in upstream data packets. |
To deactivate cable modem upstream address verification (the default), enter the no cable source-verify command.
To verify whether cable modem upstream verification has been activated or deactivated, enter the more system:running-config command and look for a cable source-verify notation in the cable interface configuration information:
CMTS01# more system:running-config
Building configuration...
Current configuration:
!
interface Cable6/0
ip address 1.1.1.1 255.255.255.0
no keepalive
cable source-verify
cable insertion-interval 2000
cable downstream annex B
cable downstream modulation 64qam
cable downstream interleave-depth 32
cable downstream symbol-rate 5056941
cable upstream 0 frequency 15008000
cable upstream 0 fec
cable upstream 0 scrambler
no cable upstream 0 shutdown
To troubleshoot the configuration, perform the following tasks:
When a cable modem is ready to join the HFC network and send data, it requests an upstream frequency from the CiscouBR7200 series. You can limit the amount of time that a cable modem can request an upstream frequency from the Cisco uBR7200 series for the first time. The initial request of a cable modem to join the network is known as initial ranging. The default insertion interval setting (automatic) configures the CiscouBR7200 series to automatically vary the initial ranging times available to new cablemodems that attempt to join the network.
|
NoteUse the default setting if a large number of cablemodems might attempt to perform initial ranging at the same time; for example, after a major power failure. |
| Command | Purpose |
|---|---|
CMTS01(config-if)# cable insertion-interval automatic | Configures the CiscouBR7200 series to automatically vary the initial ranging times available to new cablemodems that attempt to join the network. |
To ignore any minimum or maximum insertion intervals and return to the automatic setting, enter the no cable insertion-interval command.
To verify that a cable modem insertion interval has been set, enter the more system:running-config command and look for a notation in the cable interface configuration information as shown in this command output excerpt:
CMTS01# more system:running-config
Building configuration...
Current configuration:
!
interface Cable6/0
ip address 1.1.1.1 255.255.255.0
no keepalive
cable insertion-interval 2000
cable downstream annex B
cable downstream modulation 64qam
cable downstream interleave-depth 32
cable downstream symbol-rate 5056941
cable upstream 0 frequency 15008000
cable upstream 0 fec
cable upstream 0 scrambler
no cable upstream 0 shutdown
To troubleshoot the configuration, make sure that you entered the correct slot and port numbers when you typed the command.
To specify the maximum number of hosts that can be attached to a subscriber cablemodem, use the following command in cable interface configuration mode:
| Command | Purpose |
|---|---|
| Specifies the maximum number of hosts that can be attached to a cable modem on this interface. Valid range is from 0 to 255 hosts. Default = 0. |
To verify the maximum number of hosts that can be attached to a cable modem on a particular interface, enter the more system:running-config command and look for a notation in the cable interface configuration information as shown in this command output excerpt:
CMTS01# more system:running-config
Building configuration...
Current configuration:
!
interface Cable6/0
ip address 1.1.1.1 255.255.255.0
no keepalive
cable insertion-interval 2000
cable downstream annex B
cable downstream modulation 64qam
cable downstream interleave-depth 32
cable downstream symbol-rate 5056941
cable upstream 0 frequency 15008000
cable upstream 0 fec
cable upstream 0 scrambler
no cable upstream 0 shutdown
To troubleshoot the configuration, make sure that you entered the correct slot and port numbers when you typed the command.
By default, registered cable modems that have no upstream activity for three minutes are timed out and disconnected from the Cisco uBR7200 series. This timeout interval can be decreased to two minutes or increased to 60 minutes.
| Command | Purpose |
|---|---|
| Specifies the maximum number of minutes that can elapse with no upstream activity before a cable modem is declared inactive and the connection terminated. Valid range is from 2 to 60 minutes. Default = 3 minutes. |
To verify the registration timeout interval for a cable modem on a particular interface, enter the more system:running-config command and look for a notation in the cable interface configuration information as shown in this command output excerpt:
CMTS01# more system:running-config
Building configuration...
Current configuration:
!
interface Cable6/0
ip address 1.1.1.1 255.255.255.0
no keepalive
cable insertion-interval 2000
cable downstream annex B
cable downstream modulation 64qam
cable downstream interleave-depth 32
cable downstream symbol-rate 5056941
cable upstream 0 frequency 15008000
cable upstream 0 fec
cable upstream 0 scrambler
no cable upstream 0 shutdown
To troubleshoot the configuration, make sure that you entered the correct slot and port numbers when you typed the command.
| Command | Purpose |
|---|---|
| Removes the cable modem with a specific MAC address from the Station Maintenance List and resets it. |
To verify whether the clear cablemodem reset command has removed a cablemodem from the Station Maintenance List and forced it to start a reset sequence, enter the show cable modem command:
CMTS01# show cable modem 1.1.1.5 Interface US Online Timing SID QoS IP address MAC address StateOffset
To troubleshoot the configuration, perform the following tasks:
|
NoteIt might take up to 30 seconds for the cablemodem to start the reset sequence. |
| Command | Purpose |
|---|---|
| Clears the counters in the Station Maintenance List for the cable modem with a specific MAC address. |
To verify whether the counters in the Station Maintenance List have been cleared, enter the show cable flap list command. The station maintenance list counter will be 0.
CMTS01# show cable flap list
To troubleshoot the configuration, make sure you entered the correct cablemodem MAC address or IP address when you typed the command.
To ping a specific cablemodem to determine if it is online, use the following command in EXEC mode:
| Command | Purpose |
|---|---|
| Ping the cable modem with a specific MAC address or IP address to see if it is online. |
The output from the ping docsis command indicates whether or not the cable modem you were trying to contact was found on the network:
CMTS01# ping docsis 10.1.1.0
Queueing 5 MAC-layer station maintenance intervals, timeout is 25 msec:
!!!!!
Success rate is 100 percent (5/5)
To troubleshoot the configuration, make sure you are using a valid MAC or IP address for the cablemodem you want to ping.
For most of the commands described in this document, the default values are adequate to configure the Cisco uBR7200 series router. To view the current configuration of a Cisco uBR7200 series, enter the show running-config command at the CLI prompt in EXEC mode or privileged EXEC mode.
Headend broadband access router configuration examples are provided in the following sections:
In the following example, the CiscouBR7200 series is configured to support spectrum management and modulation profiles.
! version 12.1 no service pad service timestamps debug uptime service timestamps log uptime no service password-encryption ! hostname uBR7246 ! boot system flash slot0:ubr7200-p-mz.120-4.T boot system flash ! cable spectrum-group 1 frequency 40000000 cable spectrum-group 1 frequency 20000000 2 cable modulation-profile 3 request 0 16 1 8 16qam scrambler 152 no-diff 128 fixed uw16 cable modulation-profile 3 initial 5 34 0 48 16qam scrambler 152 no-diff 256 fixed uw16 cable modulation-profile 3 station 5 34 0 48 16qam scrambler 152 no-diff 256 fixed uw16 cable modulation-profile 3 short 5 75 6 8 16qam scrambler 152 no-diff 144 fixed uw8 cable modulation-profile 3 long 8 220 0 8 16qam scrambler 152 no-diff 160 fixed uw8 no cable qos permission create no cable qos permission update cable qos permission modems ip subnet-zero ip dhcp relay information option ! interface FastEthernet0/0 ip address 10.1.70.2 255.255.255.0 no ip directed-broadcast no ip mroute-cache ! ! interface Ethernet2/3 ip address 1.3.59.1 255.255.0.0 no ip directed-broadcast ! interface Cable5/0 ip address 172.1.71.1 255.255.255.0 secondary ip address 10.1.71.1 255.255.252.0 no ip directed-broadcast no ip route-cache no ip mroute-cache no keepalive no cable proxy-arp cable helper-address 10.1.70.30 cable downstream annex B cable downstream modulation 64qam cable downstream interleave-depth 32 cable upstream 0 spectrum-group 1 cable upstream 0 modulation-profile 3 cable downstream frequency 531000000 cable upstream 0 frequency 28000000 cable upstream 0 power-level 0 no cable upstream 0 shutdown cable upstream 1 shutdown cable upstream 2 shutdown cable upstream 3 shutdown cable upstream 4 shutdown cable upstream 5 shutdown ! ! router eigrp 100 network 10.0.0.0 ! ip classless no ip http server ! ! ! line con 0 password cisco login transport input none line aux 0 line vty 0 4 password cisco login ! end
VPN support enables you to offer private network connections to telecommuters and other business-oriented customers. In the following configuration example, a VPN is set up between two peer termination points: one at a remote cablemodem and the other at a VPN gateway residing at a corporate office firewall. To properly transmit and receive encrypted/decrypted traffic, each peer in the VPN must activate encryption/decryption and have matching access key strings.
|
NoteThe CiscouBR7200 series allows encrypted traffic to pass over the cable network (and often the Internet) from one peer to the other, based on a routing table setup in its configuration file. Following is a typical routing setup. |
! version 12.1 no service pad service timestamps debug uptime service timestamps log uptime no service password-encryption ! hostname uBR7246 ! boot system flash slot0:ubr7200-k1p-mz_120-4_XI1 enable password **** ! username smith privilege 15 password **** cable flap-list aging 1 cable spectrum-group 1 band 20000000 26400000 cable spectrum-group 2 frequency 20000000 cable spectrum-group 2 frequency 20000000 2 cable spectrum-group 2 frequency 20000000 -2 cable spectrum-group 2 frequency 22000000 cable spectrum-group 2 frequency 22000000 2 cable spectrum-group 2 frequency 22000000 3 no cable qos permission create no cable qos permission update cable qos permission modems ip subnet-zero ip host abrick 223.255.254.254 ! ! ! interface FastEthernet0/0 ip address 10.30.0.1 255.255.0.0 no ip directed-broadcast full-duplex no cdp enable ! interface FastEthernet1/0 ip address 10.31.0.1 255.255.0.0 ip helper-address 10.0.0.101 no ip directed-broadcast full-duplex no cdp enable ! interface Ethernet2/0 ip address 10.32.0.1 255.255.0.0 no ip directed-broadcast no cdp enable ! interface Ethernet2/1 no ip address no ip directed-broadcast shutdown no cdp enable ! interface Ethernet2/2 no ip address no ip directed-broadcast shutdown no cdp enable ! interface Ethernet2/3 no ip address no ip directed-broadcast shutdown no cdp enable ! interface Cable3/0 mac-address 1033.0000.1c30 ip address 10.33.0.1 255.255.0.0 no ip redirects no ip directed-broadcast ip helper-address 10.0.0.101 load-interval 30 no keepalive cable spectrum-group 1 cable downstream annex B cable downstream modulation 64qam cable downstream interleave-depth 32 cable downstream frequency 453000000 no cable upstream 0 shutdown cable upstream 1 frequency 18000000 cable upstream 1 power-level 0 no cable upstream 1 shutdown cable upstream 2 frequency 18000000 cable upstream 2 power-level 0 no cable upstream 2 shutdown cable upstream 3 frequency 18000000 cable upstream 3 power-level 0 no cable upstream 3 shutdown cable upstream 4 frequency 18000000 cable upstream 4 power-level 0 no cable upstream 4 shutdown cable upstream 5 frequency 18000000 cable upstream 5 power-level 0 no cable upstream 5 shutdown ! interface Cable4/0 no ip address no ip directed-broadcast no keepalive shutdown cable downstream annex B cable downstream modulation 64qam cable downstream interleave-depth 32 cable upstream 0 shutdown cable upstream 1 shutdown cable upstream 2 shutdown cable upstream 3 shutdown cable upstream 4 shutdown cable upstream 5 shutdown ! ip classless ip route 0.0.0.0 0.0.0.0 10.30.0.10 ip route 10.51.0.0 255.255.0.0 10.32.0.10 ip route 10.100.1.0 255.255.255.248 10.33.1.10 ip flow-export destination 10.32.0.8 9995 ip http server ip http authentication local ! no cdp run snmp-server engineID local 00000009020000905F0E7800 snmp-server community public RW ! tftp-server flash slot0:basic.cfg tftp-server flash slot0:boot.tft tftp-server flash slot0:bootmin.tftp alias exec shcm show cable modem ! line con 0 exec-timeout 0 0 transport input none line aux 0 line vty 0 1 exec-timeout 0 0 password lab login length 0 line vty 2 exec-timeout 0 0 password lab login line vty 3 exec-timeout 0 0 password lab login length 0 line vty 4 exec-timeout 0 0 password lab login ! end
Following is a sample VoIP configuration file for a Cisco uBR7200 series cable router:
|
CautionIn certain countries, the provisioning of voice telephony over the Internet may be prohibited or subject to laws, regulations, or licenses, including requirements applicable to the use of the products under telecommunications and other laws and regulations; you must comply with all such applicable laws in the country or countries where you intend to use the product. |
version 12.1 no service pad service timestamps debug uptime service timestamps log uptime no service password-encryption ! hostname twoslot ! enable password **** !cable modulation-profile 2 request 0 16 1 8 16qam scrambler 152 no-diff 256 fixed uw16cable modulation-profile 2 initial 5 34 0 48 16qam scrambler 152 no-diff 256 fixed uw16cable modulation-profile 2 station 5 34 0 48 16qam scrambler 152 no-diff 256 fixed uw16cable modulation-profile 2 short 6 75 6 8 16qam scrambler 152 no-diff 144 fixed uw8cable modulation-profile 2 long 8 220 0 8 16qam scrambler 152 no-diff 160 fixed uw8cable modulation-profile 3 initial 5 34 0 48 16qam scrambler 152 no-diff 128 shortened uw16cable modulation-profile 3 station 5 34 0 48 16qam scrambler 152 no-diff 128 shortened uw16cable modulation-profile 3 short 5 75 6 8 16qam scrambler 152 no-diff 80 shortened uw8cable modulation-profile 3 long 8 220 0 8 16qam scrambler 152 no-diff 80 shortened uw8cable modulation-profile 4 request 0 16 1 8 qpsk scrambler 152 no-diff 64 shortened uw16cable modulation-profile 4 initial 5 34 0 48 qpsk scrambler 152 no-diff 128 shortened uw16cable modulation-profile 4 station 5 34 0 48 qpsk scrambler 152 no-diff 128 shortened uw16cable modulation-profile 4 short 5 75 6 8 qpsk scrambler 152 no-diff 72 shortened uw8cable modulation-profile 4 long 8 220 0 8 qpsk scrambler 152 no-diff 80 shortened uw8cable modulation-profile 5 request 0 16 2 8 qpsk scrambler 152 no-diff 64 fixeduw8cable modulation-profile 5 initial 5 34 0 48 qpsk scrambler 152 no-diff 128 fixed uw16cable modulation-profile 5 short 5 78 8 8 16qam scrambler 152 no-diff 144 shortened uw8cable modulation-profile 5 long 10 235 8 8 16qam scrambler 152 no-diff 160 shortened uw8cable modulation-profile 6 request 0 16 1 8 16qam scrambler 152 no-diff 128 shortened uw16cable modulation-profile 6 initial 5 34 0 48 16qam scrambler 152 no-diff 256 shortened w16cable modulation-profile 6 station 5 34 0 48 16qam scrambler 152 no-diff 256 shortened uw16cable modulation-profile 6 short 6 75 6 8 16qam scrambler 152 no-diff 144 shortened uw8cable modulation-profile 6 long 8 220 0 8 16qam scrambler 152 no-diff 160 shortened uw8cable modulation-profile 7 request 0 16 1 8 16qam scrambler 152 no-diff 128 fixed uw16cable modulation-profile 7 initial 5 34 0 48 16qam scrambler 152 no-diff 256 fixed uw16cable modulation-profile 7 station 5 34 0 48 16qam scrambler 152 no-diff 256 fixed uw16cable modulation-profile 7 short 6 75 6 8 16qam scrambler 152 no-diff 144 fixed uw8cable modulation-profile 7 long 8 220 0 8 16qam scrambler 152 no-diff 160 fixed uw8cable modulation-profile 8 request 0 16 1 8 qpsk scrambler 152 no-diff 64 fixed uw8cable modulation-profile 8 initial 5 34 0 48 16qam scrambler 152 no-diff 256 fixed uw16cable modulation-profile 8 station 5 34 0 48 16qam scrambler 152 no-diff 256 fixed uw16cable modulation-profile 8 short 6 75 6 8 16qam scrambler 152 no-diff 144 fixed uw8cable modulation-profile 8 long 8 220 0 8 16qam scrambler 152 no-diff 160 fixed uw8 no cable qos permission create no cable qos permission update cable qos permission modems ! ! ! ! ip subnet-zero no ip domain-lookup ip host abrick 223.255.254.254 ip host muck 255.255.255.255 ip host keyer 223.255.254.254 ip host bell 223.255.254.253 ! ! !interface FastEthernet0/0ip address 2.2.2.2 255.255.255.0no ip directed-broadcast no ip mroute-cache shutdown !interface Ethernet1/0ip address 1.11.8.1 255.255.0.0ip broadcast-address 1.11.255.255ip helper-address 223.255.254.254no ip directed-broadcast no ip mroute-cache !interface Ethernet1/1ip address 10.20.122.2 255.255.255.192ip helper-address 10.0.0.2no ip directed-broadcast ! interface Ethernet1/2 no ip address no ip directed-broadcast shutdown ! interface Ethernet1/3 no ip address no ip directed-broadcast shutdown !interface Cable2/0ip address 20.20.20.20 255.255.255.0no ip directed-broadcast no keepalivecable downstream modulation 64qamcable upstream 0 frequency 10000000cable upstream 0 power-level 0no cable upstream 0 shutdowncable upstream 1 frequency 10000000cable upstream 1 power-level 0no cable upstream 1 shutdowncable upstream 2 shutdown cable upstream 3 shutdown cable upstream 4 shutdown cable upstream 5 shutdown !ip default-gateway 1.11.0.1ip classlessip route 0.0.0.0 0.0.0.0 10.20.122.1ip route 223.255.254.254 255.255.255.255 1.11.0.1ip http server!!tftp-server flash slot1:ubr920-y5-mz.euro alias ubr900! ! line con 0 exec-timeout 0 0 transport input none line aux 0 line vty 0 4 login line vty 5 11 login ! end
Following is a sample configuration file displaying critical elements of a telco return network configuration for the Cisco uBR7200 series, including the following:
|
NoteSome telco return cablemodems cannot receive traffic over the same downstream channel as cablemodems operating on a two-way data system. In a cable network where you plan to service both telco return and two-way cablemodems, you may need to segment your cable headend to allow more than one downstream channel. |
version 12.1service timestamps debug uptimeservice timestamps log uptimeservice password-encryption!hostname uBR7246!boot system flash slot0:ubr7200-p-mz.**********boot system flashlogging buffered 100000 debuggingaaa new-modelaaa authentication login default radius enableaaa authentication login vty lineaaa accounting update newinfoaaa accounting exec default start-stop radiusaaa accounting commands 15 default start-stop radiusaaa accounting network default start-stop radiusaaa accounting system default start-stop radiusenable secret guess_my_password_ha_ha_ha.!no cable qos permission createno cable qos permission updatecable qos permission modemsip subnet-zerono ip fingerno ip domain-lookup!!interface Loopback0ip address 24.1.2.246 255.255.255.0no ip directed-broadcast!interface FastEthernet0/0no ip addressno ip directed-broadcastshutdownmedia-type MIIfull-duplex!interface Hssi1/0ip unnumbered Loopback0no ip directed-broadcast!interface Cable3/0ip address 10.1.1.1 255.255.255.0no ip directed-broadcastip helper-address 24.1.1.84no keepalivecable downstream annex Bcable downstream modulation 64qamcable downstream interleave-depth 32cable downstream frequency 687000000cable upstream 0 frequency 13008000no cable upstream 0 shutdowncable upstream 1 shutdowncable upstream 2 shutdowncable upstream 3 shutdowncable upstream 4 shutdowncable upstream 5 shutdown!interface Cable6/0ip address 172.16.1.1 secondaryip address 10.1.1.1no ip directed-broadcastip helper-address 24.1.1.84no keepalivecable downstream annex Bcable downstream modulation 64qamcable downstream interleave-depth 32cable downstream frequency 687000000cable upstream 0 frequency 13008000no cable upstream 0 shutdowncable telco-return enablecable telco-return spd 1 factory-defaultcable telco-return spd 1 dhcp-authenticatecable telco-return spd 1 dhcp-server 24.1.1.84cable telco-return spd 1 ppp-authenticate chapcable telco-return spd 1 phonenum 918005555555cable telco-return spd 1 phonenum 18005555555cable telco-return spd 1 username testcable telco-return spd 1 password test!router ospf 100network 10.0.0.0 0.255.255.255 area 0network 24.1.0.0 0.0.255.255 area 0!ip classlessip route 0.0.0.0 0.0.0.0 24.1.2.21!logging 24.1.1.78snmp-server community public ROsnmp-server community favorite_server_community RWsnmp-server location favorite_location!radius-server host 24.1.1.78 auth-port 1645 acct-port 1646radius-server key radius_server_key!line con 0password No need to change; this is encrypted already.transport input noneflowcontrol softwareline aux 0password No need to change; this is encrypted already.flowcontrol hardwareline vty 0 4password No need to change; this is encrypted already.login authentication vtyend
The following example shows how a cable modem with a QoS profile of 4, created by the cable modem (cm), is reset to use QoS profile 225 enforced by the Cisco uBR7200 series (management):
CMTS01# show cable modem
Interface SID Online Timing Receive QoS IP address MAC
address
State Offset Power
Cable6/0/U0 1 online 2848 0.00 4 19.2.20.139 0010.7b6b.7215
CMTS01# show cable qos profile 4
Service Prio Max Guarantee Max Max tx TOS TOS Create B
class upstream upstream downstream burst mask value by priv
bandwidth bandwidth bandwidth enab
4 7 128000 64000 2048000 255 0x0 0x0 cm no
CMTS01(config)# cable qos profile 225 max-upstream 256
CMTS01(config)# cable qos permission enforce 225
CMTS01# clear cable modem all reset
CMTS01# show cable modem
Interface SID Online Timing Receive QoS IP address MACaddress
State Offset Power
Cable6/0/U0 1 offline 2848 0.25 2 19.2.20.139 0010.7b6b.7215
CMTS01# debug cable reg
....
00:15:59: Finished parsing REG Request
00:15:59: Overriding Provisioned QoS Parameters In REG-REQ
....
CMTS01# show cable modem
Interface SID Online Timing Receive QoS IP address MACaddress
State Offset Power
Cable6/0/U0 1 online 2852 0.00 225 19.2.20.139 0010.7b6b.7215
CMTS01# show cable qos profile 225
Service Prio Max Guarantee Max Max tx TOS TOS Create B
class upstream upstream downstream burst mask value by priv
bandwidth bandwidth bandwidth enab
225 0 256000 0 0 0 0x0 0x0 management no
The following tips and scenarios allow you to use the flap list in the most effective way:
You can specify the number of days to record and retain flapping activity on cablemodems currently in the flap list table. This value is known as the age of the flap list. The valid range is from 1to60days.
To set the age of the flap list, use the following command in global configuration mode:
| Command | Purpose |
|---|---|
| Specifies the number of days to record and retain flapping activity for the cable modems connected to this CiscouBR7200 series router. |
To verify that cable flap list aging is set, enter the show cable flap list command:
CMTS01# show cable flap list
Mac Addr CableIF Ins Hit Miss CRC P-Adj Flap Time
0010.7b6b.5d1d C3/0 U0 0 688 169 0 0 3 Nov 5 12:28:50
0010.7b6b.5e15 C3/0 U0 1 707 185 0 0 5 Nov 5 12:29:52
0010.7b6b.5e27 C3/0 U0 1 707 198 0 0 5 Nov 5 12:29:55
0010.7b6b.5d29 C3/0 U0 1 709 205 0 0 5 Nov 5 12:29:52
0010.7b6b.5e2b C3/0 U0 1 710 204 0 0 7 Nov 5 12:30:16
You can set the cable flap list insertion time. When a cablemodem makes an insertion request more frequently than the amount of insertion time defined by this command, the cablemodem is placed in the flap list for activity recording. The valid range is from 60 to 86400 seconds.
To set the cable flap list insertion time, use the following command in global configuration mode:
| Command | Purpose |
|---|---|
| Specifies the insertion time in seconds. Any cable modem that makes an insertion request more frequently than this period of time is placed in the flap list. |
To verify cable flap list insertion time, enter the show cable flap list command:
CMTS01# show cable flap list
Mac Addr CableIF Ins Hit Miss CRC P-Adj Flap Time
0010.7b6b.5d1d C3/0 U0 0 688 169 0 0 3 Nov 5 12:28:50
0010.7b6b.5e15 C3/0 U0 1 707 185 0 0 5 Nov 5 12:29:52
0010.7b6b.5e27 C3/0 U0 1 707 198 0 0 5 Nov 5 12:29:55
0010.7b6b.5d29 C3/0 U0 1 709 205 0 0 5 Nov 5 12:29:52
0010.7b6b.5e2b C3/0 U0 1 710 204 0 0 7 Nov 5 12:30:16
You can specify the power adjustment threshold that will cause a flap list event to be recorded. When the power adjustment of a cablemodem meets or exceeds the threshold, the cablemodem is placed in the flaplist. The valid range is from 1 to 10 dBmV.
|
NoteA power adjustment threshold of less than 2dBmV might cause excessive flap list event recording. We recommend setting this threshold value to 3dBmV or higher. |
| Command | Purpose |
|---|---|
| Specifies the minimum power adjustment that will constitute a flap list event. |
To verify the cable flap list power adjustment threshold, enter the show cable flap list command:
CMTS01# show cable flap list
Mac Addr CableIF Ins Hit Miss CRC P-Adj Flap Time
0010.7b6b.5d1d C3/0 U0 0 688 169 0 0 3 Nov 5 12:28:50
0010.7b6b.5e15 C3/0 U0 1 707 185 0 0 5 Nov 5 12:29:52
0010.7b6b.5e27 C3/0 U0 1 707 198 0 0 5 Nov 5 12:29:55
0010.7b6b.5d29 C3/0 U0 1 709 205 0 0 5 Nov 5 12:29:52
0010.7b6b.5e2b C3/0 U0 1 710 204 0 0 7 Nov 5 12:30:16
You can specify the miss threshold for recording a flap list event. A miss is the number of times a cablemodem does not acknowledge a MAC-layer keepalive message from a cablemodem card. An 8 percent miss rate is normal for the Cisco cablemodem cards. When the number of misses exceeds the threshold, the cablemodem is placed in the flap list.
|
NoteA high miss rate can indicate intermittent upstream problems, fiber laser clipping, or common-path distortion. |
| Command | Purpose |
|---|---|
| Specifies the number of MAC-layer keepalive misses that will result in the cable modems being place in the flap list. |
To verify the cable flap list miss threshold, enter the show cable flap list command:
CMTS01# show cable flap list
Mac Addr CableIF Ins Hit Miss CRC P-Adj Flap Time
0010.7b6b.5d1d C3/0 U0 0 688 169 0 0 3 Nov 5 12:28:50
0010.7b6b.5e15 C3/0 U0 1 707 185 0 0 5 Nov 5 12:29:52
0010.7b6b.5e27 C3/0 U0 1 707 198 0 0 5 Nov 5 12:29:55
0010.7b6b.5d29 C3/0 U0 1 709 205 0 0 5 Nov 5 12:29:52
0010.7b6b.5e2b C3/0 U0 1 710 204 0 0 7 Nov 5 12:30:16
You can specify the maximum number of cablemodems that can be listed in the cable flap list tables. The valid range is from 1 to 8192 cablemodems. The default is 8192 cablemodems.
| Command | Purpose |
|---|---|
| Specifies the maximum size of the flap list. |
To verify the cable flap list size, enter the show cable flap list command:
CMTS01# show cable flap list
Mac Addr CableIF Ins Hit Miss CRC P-Adj Flap Time
0010.7b6b.5d1d C3/0 U0 0 688 169 0 0 3 Nov 5 12:28:50
0010.7b6b.5e15 C3/0 U0 1 707 185 0 0 5 Nov 5 12:29:52
0010.7b6b.5e27 C3/0 U0 1 707 198 0 0 5 Nov 5 12:29:55
0010.7b6b.5d29 C3/0 U0 1 709 205 0 0 5 Nov 5 12:29:52
0010.7b6b.5e2b C3/0 U0 1 710 204 0 0 7 Nov 5 12:30:16
| Command | Purpose |
|---|---|
| Clears the entries in the cable flap list for the cable modem with this MAC address. |
Posted: Thu Jul 27 00:04:11 PDT 2000
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