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This document describes the Telco Return feature for the Cisco uBR7200 series universal broadband router. The Telco Return feature implements the Data-over-Cable System Interface Specification (DOCSIS) standard for telephony return, giving cable operators that support only one-way radio frequency (RF) transmission the ability to provide Internet access to subscribers. With telco return, the upstream connection from the subscriber's cable modem to the headend is employed over standard phone lines.
This document includes the following sections:
In telco return configurations, the Cisco uBR7200 series universal broadband router provides downstream data flow 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. Upstream data is through a telephone modem (external or internal to a cable modem, as well as a cable modem card in a PC, based on the third-party cable modem vendor) connected to an analog telephone line typically. This enables cable companies that do not support two-way RF transmission or that have not upgraded specific service areas to offer fast downstream data services via the cable plant and upstream transmission via the PSTN.
Figure 1 illustrates a telco return configuration.
Downstream traffic is 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. The dialing and access attributes are defined in the Service Provider Descriptor (SPD). Each TCD message contains at least one and as many as five SPDs.
The SPD within TCD packets contains three critical telco return elements:
When connected, the network access server feeds the subscriber username and password to a RADIUS dial security server for authentication. When access is granted, the network server sets up a Point-to-Point Protocol (PPP) negotiation and connection. The dialing and access attributes in the SPD are defined through Cisco IOS. For a description of the related commands, see the "Command Reference" section.
Cisco uBR7200 series
Standards
DOCSIS Cable Modem Telephony Return Interface Specification (SP-CMTRI-I01-970804)
MIBs
No new or modified MIBs are supported by this feature.
RFCs
No new or modified RFCs are supported by this feature.
To use the Telco Return feature, you must ensure that:
See the following tasks to configure the Telco Return feature:
To enable telco return on the Cisco uBR7200 series, perform the following steps in interface configuration mode:
| Command | Purpose | |
Step 1 | Router(config)# | Enters interface configuration mode. |
Step 1 | Router(config-if)# | Enables telco return. |
Step 2 | Router(config-if)# | Sets the interval for sending Telephony Channel Descriptor (TCD) and Termination System Information (TSI) messages to the downstream cable modems. |
To define the telephony attributes contained in the Service Provider Descriptor (SPD) sent in TCD messages, perform the following steps in interface configuration mode:
| Command | Purpose | |
|---|---|---|
Step 1 | Router(config)# | Enters interface configuration mode. |
Step 2 | Router(config-if)# | Sets the telephone numbers that the telco return cable modem uses to connect to the headend's network access server. |
Step 3 | Router(config-if)# | Sets the username that the telco return cable modem uses for authentication when establishing a PPP connection. |
Step 4 | Router(config-if)# | Sets the password that the telco return cable modem uses for authentication when establishing a PPP connection. |
Step 5 | Router(config-if)# | Selects the authentication procedure that is used when the telco-return cable modem is establishing a PPP connection. |
Step 6 | Router(config-if)# | Selects a RADIUS server domain for the login response string. |
Step 7 | Router(config-if)# | Requires the telco-return cable modem to use a specific Dynamic Host Configuration Protocol (DHCP) server. |
Step 8 | Router(config-if)# | Identifies the IP address of the Dynamic Host Configuration Protocol (DHCP) server that the telco-return cable modem must access. |
Step 9 | Router(config-if)# | Sets the number of seconds that a telephone connection is idle before the telco-return cable modem disconnects the call. |
Step 10 | Router(config-if)# | Sets the number of failed dial-up connections that can occur before the cable modem indicates a connection failure. |
Step 11 | Router(config-if)# | Includes the service provider name in the SPD. |
Step 12 | Router(config-if)# | Indicates the SPD that the telco-return cable modem uses during the initialization process. |
Step 13 | Router(config-if)# | Enables the telco-return cable modem to operate in manual dial mode. |
To configure a different registration IP address in the TSI message, perform the following steps in interface configuration mode:
| Command | Purpose | |
Step 1 | Router(config)# | Enters interface configuration mode. |
Step 1 | Router(config-if)# | Selects an alternate IP address for the telco-return cable modem to send registration requests. |
To verify that the subscriber modem can log into the Cisco uBR7200 series in telco-return mode:
Step 2 Allow the subscriber modem to complete telco registration (will take several minutes).
Step 3 Enter the show cable modem command on the Cisco uBR7200 series to verify that the subscriber modem is shown in the list. The letter "T" indicates that a modem is a telco-return modem.
ubr7246-1# show cable modem
Interface Prim Online Timing Rec QoS CPE IP address MAC address
Sid State Offset Power
Cable4/0/U0 2 online 2848 -0.50 5 1 10.2.0.3 0010.7b6b.53d5
Cable4/0/T 3 offline 0 0.00 2 1 10.2.0.101 0020.4001.4af6
Cable4/0/U0 4 online 2852 -0.75 5 1 10.2.0.6 0010.7b6b.7255
Cable4/0/U0 5 online 2850 0.25 5 1 10.2.0.7 0010.7b6b.5669
Cable4/0/U0 6 online 2851 0.00 2 1 10.2.0.4 0010.7b6b.53c9
Cable4/0/T 7 offline 0 0.00 2 0 10.2.0.102 0020.4001.4b32
Step 4 Ping the subscriber modem from the Cisco uBR7200 series to ensure that the router receives the echo reply packets.
 |
Note The ping docsis command is not supported for telco-return cable modems, and telco-return cable modems are not displayed when using the show cable flap list command. The clear cable modem reset command has no effect on one-way cable modems. |
The following example displays the screen output using the show running-config command:
! interface cable 6/0 ip address 172.16.1.1 secondary ip address 10.1.1.1 no ip directed-broadcast ip helper-address 192.168.1.1 no keepalive cable insertion-interval 500 cable downstream annex B cable downstream modulation 64qam cable downstream interleave-depth 32 cable downstream frequency 687000000 cable upstream 0 frequency 13008000 no cable upstream 0 shutdown cable telco-return enable cable telco-return spd 1 factory-default cable telco-return spd 1 phonenum 8005551212 cable telco-return spd 1 phonenum 4085551212 cable telco-return spd 1 phonenum 6505551212 cable telco-return spd 1 service-provider norcal cable telco-return spd 1 dhcp-server 172.31.172.172 cable telco-return spd 1 username joe cable telco-return spd 1 password testing cable telco-return spd 1 dhcp-authenticate cable telco-return spd 1 threshold 5 cable telco-return spd 1 ppp-authenticate both cable telco-return spd 1 manual-dial cable telco-return spd 1 dial-timer 7200 cable telco-return registration-ip 172.16.1.1 !
This section documents new commands. All other commands used with this feature are documented in the Cisco IOS Release 12.1 command references.
To enable telco return support, use the cable telco-return enable interface configuration command. To disable this feature, use the no form of this command.
cable telco-return enableSyntax Description
This command has no arguments or keywords.
Defaults
Telco return support is disabled.
Command Modes
Interface configuration
Command History
12.0(4)XI This command was introduced.
Release
Modification
Examples
The following example enables telco return:
interface cable 6/0 cable telco-return enable
Related Commands
Defines the interval for sending Telephony Channel Descriptor (TCD) and Termination System Information (TSI) messages.
Command
Description
To set the interval for sending Telephony Channel Descriptor (TCD) and Termination System Information (TSI) messages, use the cable telco-return interval interface configuration command. To restore the default value, use the no form of this command.
cable telco-return interval seconds
Syntax Description
seconds Number of seconds between intervals for sending TCD and TSI messages. Valid range is 2 through 60 seconds.
Defaults
2 seconds
Command Modes
Interface configuration
Command History
12.0(4)XI This command was introduced.
Release
Modification
Examples
The following example sets the TCD and TSI message interval to 40 seconds:
interface cable 6/0 cable telco-return interval 40
Related Commands
Enables telco return functionality.
Command
Description
To select an alternate IP address for the telco-return cable modem to send its registration requests, use the cable telco-return registration-ip interface configuration command. To restore the default value, use the no form of this command.
cable telco-return registration-ip ip-address
Syntax Description
ip-address Registration IP address that is sent in Termination System Information (TSI) messages.
Defaults
The downstream channel IP address of the Cisco uBR7200 series is used.
Command Modes
Interface configuration
Command History
12.1(2)EC This command was introduced.
Release
Modification
Usage Guidelines
This command sets the Registration IP Address parameter in TSI messages. By default, the downstream channel IP address of the Cisco uBR7200 series is also used for the registration IP address. When this cable telco-return registration-ip command is configured, telco return cable modems send their registration requests to this IP address instead of to the downstream channel IP address.
Examples
The following example sends the cable modem's registration requests to IP address 172.16.1.1:
interface cable 6/0 cable telco-return registration-ip 172.16.1.1
Related Commands
Enables telco return functionality. Sets the interval for sending Telephony Channel Descriptor (TCD) and Termination System Information (TSI) messages.
Command
Description
To require the telco-return cable modem to use a specific Dynamic Host Configuration Protocol (DHCP) server, use the cable telco-return spd dhcp-authenticate interface configuration command. To restore the default value, use the no form of this command.
cable telco-return spd spd-number dhcp-authenticate
Syntax Description
spd-number Service provider descriptor number for which this parameter is set. Valid range is 1 through 5.
Defaults
The cable modem can use any available DHCP server.
Command Modes
Interface configuration
Command History
12.0(4)XI This command was introduced.
Release
Modification
Usage Guidelines
This command sets the DHCP Authenticate parameter to True (1) for the specified SPD in the TCD messages. It indicates that the cable modem must use the DHCP server that is specified with the cable telco-return spd dhcp-server command.
Examples
The following example indicates that for SPD 2, cable modems must use the DHCP server identified by IP address 192.168.255.255:
interface cable 6/0 cable telco-return spd 2 dhcp-authenticate cable telco-return spd 2 dhcp-server 192.168.255.255
Related Commands
Enables telco return functionality. Identifies the IP address of the DHCP server that the telco return cable modems must use.
Command
Description
To identify the IP address of the Dynamic Host Configuration Protocol (DHCP) server that the telco-return cable modem must access, use the cable telco-return spd dhcp-server interface configuration command. To restore the default value, use the no form of this command.
cable telco-return spd spd-number dhcp-server ip-address
Syntax Description
spd-number Service provider descriptor number for which this parameter is set. Valid range is 1 through 5. ip-address IP address of the DHCP server that cable modems must use.
Defaults
The IP address is set to 0.
Command Modes
Interface configuration
Command History
12.0(4)XI This command was introduced.
Release
Modification
Usage Guidelines
This command sets the DHCP Server parameter in the specified SPD in TCD messages. Telco return cable modems use the DHCP server that is identified by this IP address if the cable telco-return spd dhcp-authenticate command is configured. If the cable telco-return spd dhcp-authenticate command is not configured, the cable modems will use any available DHCP server.
Examples
The following example indicates that for SPD 2, cable modems must use the DHCP server identified by IP address 192.168.255.255:
interface cable 6/0 cable telco-return spd 2 dhcp-authenticate cable telco-return spd 2 dhcp-server 192.168.255.255
Related Commands
Enables telco return functionality. Indicates that telco return cable modems must use a specific Dynamic Host Configuration Protocol (DHCP) server.
Command
Description
To set the number of seconds that a telephone connection is idle before the telco-return cable modem disconnects the call, use the cable telco-return spd dial-timer EXEC command. To restore the default value, use the no form of this command.
cable telco-return spd spd-number dial-timer seconds
Syntax Description
spd-number Service provider descriptor number for which this parameter is set. Valid range is 1 through 5. seconds Number of seconds that a connection is idle before the cable modem disconnects the call. Valid range is 0 through 4,294,967,295. The default of 0 means that the dial-timer is not used.
Defaults
The dial-timer is set to 0, which means that inactive telephone connections are not disconnected.
Command Modes
Interface configuration
Command History
12.0(4)XI This command was introduced.
Release
Modification
Usage Guidelines
This command sets the Demand Dial Timer parameter for the specified SPD in TCD messages. This enables the cable modem to emulate true dial-on-demand functionality by monitoring inactive networking time and allowing it to disconnect any telephone connection that exceeds the timer.
Examples
The following example sets the timer to 2 hours:
interface cable 6/0 cable telco-return spd 2 dial-timer 7200
Related Commands
Enables telco return functionality. Sets the telephone numbers that the telco-return cable modem dials when connecting to the headend's network access server. Selects the authentication procedure to use when the telco-return cable modem is establishing a PPP connection.
Command
Description
To indicate the service provider descriptor (SPD) that the telco-return cable modem uses during the initialization process, use the cable telco-return spd factory-default interface configuration command. To restore the default value, use the no form of this command.
cable telco-return spd spd-number factory-default
Syntax Description
spd-number Service provider descriptor that contains the set of telephony attributes used by the cable modem during initialization. Valid range is 1 through 5.
Defaults
The Factory Default Flag in the SPD is set to 0, which means that this SPD is not used for the initialization process.
Command Modes
Interface configuration
Command History
12.0(4)XI This command was introduced.
Release
Modification
Usage Guidelines
This command sets the Factory Default parameter in the specified SPD in TCD messages. This determines the set of telephony attributes, as defined by the SPD, that are used for the initialization process when the cable modem is powered on or is reset to its factory default.
Examples
The following example instructs the telco-return cable modem to use SPD 2 during the initialization procedure:
interface cable 6/0 cable telco-return spd 2 factory-default
Related Commands
Enables telco return functionality. Includes the service provider name in the SPD.
Command
Description
To enable the telco-return cable modem to operate in manual-dial mode, use the cable telco-return spd manual-dial interface configuration command. To restore the default value, use the no form of this command.
cable telco-return spd spd-number manual-dial
Syntax Description
spd-number Service provider descriptor number for which this parameter is set. Valid range is 1 through 5.
Defaults
Manual-dial mode is disabled.
Command Modes
Interface configuration
Command History
12.0(4)XI This command was introduced.
Release
Modification
Usage Guidelines
This command sets the Manual Dial vendor-specific parameter in the specified SPD in TCD messages.
Examples
The following example sets manual-dial mode for SPD 1:
interface cable 6/0 cable telco-return spd 1 manual-dial
Related Commands
Enables telco-return functionality. Sets the number of seconds that a telephone connection is idle before the telco-return cable modem disconnects the call.
Command
Description
To set the password that the telco-return cable modem uses for authentication when establishing a PPP connection with the access server, use the cable telco-return spd password interface configuration command. To restore the default value, use the no form of this command.
cable telco-return spd spd-number password password-string
Syntax Description
spd-number Service provider descriptor number for which this parameter is set. Valid range is 1 through 5. password-string Login password that the cable modem uses for authentication during the initialization procedure.
Defaults
No password is used.
Command Modes
Interface configuration
Command History
12.0(4)XI This command was introduced.
Release
Modification
Usage Guidelines
This command sets the Login Password parameter for the specified SPD in TCD messages.
Examples
The following example sets the password to 9JwoKd7 in service provider descriptor 2:
interface cable 6/0 cable telco-return spd 2 password 9JwoKd7
Related Commands
Enables telco-return functionality. Sets the telephone numbers that the telco-return cable modem dials when connecting to the headend's network access server. Sets the username that the telco-return cable modem uses for authentication when establishing a PPP connection.
Command
Description
To set the telephone numbers that the telco-return cable modem uses when connecting to the headend's network access server, use the cable telco-return spd phonenum interface configuration command. To delete previously entered telephone numbers, use the no form of this command.
cable telco-return spd spd-number phonenum dial-string
Syntax Description
spd-number Service provider descriptor number for which this parameter is set. Valid range is 1 through 5. dial-string Telephone number that the cable modem uses to connect to the headend's network access server.
Defaults
No default behavior or values.
Command Modes
Interface configuration
Command History
12.0(4)XI This command was introduced.
Release
Modification
Usage Guidelines
This command sets the Phone Number parameters in the specified SPD in TCD messages. You can repeat this command, entering as many as three telephone numbers for the cable modem to use when attempting to establish a PPP connection with the network access server. The phone numbers are mapped to the parameters Phone Number1, Phone Number2, Phone Number3 in the order in which you enter them. The cable modem attempts to connect using Phone Number1 first. If it fails to connect, and its number of retries exceeds the limit set with the cable telco-return spd threshold command, the cable modem dials the next number in the list.
Examples
The following example sets the primary phone number to 9255551212. If the cable modem fails to connect using that number, it will try the next phone number, 9255551234:
interface cable 6/0 cable telco-return spd 2 phonenum 9255551212 cable telco-return spd 2 phonenum 9255551234
Related Commands
Enables telco-return functionality. Sets the password that the telco-return cable modem uses for authentication when establishing a PPP connection. Sets the username that the telco-return cable modem uses for authentication when establishing a PPP connection.
Command
Description
To select the authentication method used when the telco-return cable modem is establishing a PPP connection, use the cable telco-return spd ppp-authenticate interface configuration command. To restore the default value, use the no form of this command.
cable telco-return spd spd-number ppp-authenticate [both | chap | pap]
Syntax Description
spd-number Service provider descriptor number for which this parameter is set. Valid range is 1 through 5. both Challenge Handshake Authentication Protocol (CHAP) is used if the network access server supports CHAP. Password Authentication Protocol (PAP) is used only if the network access server does not support CHAP. chap CHAP authentication is used. pap PAP authentication is used.
Defaults
The default is both; either CHAP or PAP is used depending on the methods supported by the network access server.
Command Modes
Interface configuration
Command History
12.0(4)XI This command was introduced.
Release
Modification
Usage Guidelines
This command sets the PPP Authentication parameter for the specified SPD in TCD messages.
Examples
The following example requires the cable modem to perform CHAP authentication:
interface cable 6/0 cable telco-return spd 2 ppp-authenticate chap
Related Commands
Enables telco-return functionality. Sets the password that the telco-return cable modem uses for authentication when establishing a PPP connection. Specifies the Telephone Numbers parameter in TCD messages. Sets the username that the telco-return cable modem uses for authentication when establishing a PPP connection.
Command
Description
To select a RADIUS server domain to use for the login response string, use the cable telco-return spd radius-realm interface configuration command. To restore the default value, use the no form of this command.
cable telco-return spd spd-number radius-realm string
Syntax Description
spd-number Service provider descriptor number for which this parameter is set. Valid range is 1 through 5. string Alphanumeric string identifying a RADIUS server domain.
Defaults
The default value is the null string.
Command Modes
Interface configuration
Command History
12.0(4)XI This command was introduced.
Release
Modification
Usage Guidelines
This command sets the RADIUS Realm parameter for the specified SPD in TCD messages. When this command is configured, telco return cable modems use this realm string to construct a domain name for the login username when responding to a PPP login query.
Examples
The following example indicates a login response string of sandy@sunol:
interface cable 6/0 cable telco-return spd 3 radius-realm sunol cable telco-return spd 3 username sandy
Related Commands
Enables telco-return functionality. Sets the username that the telco-return cable modem uses for authentication when establishing a PPP connection. Sets the password that the telco-return cable modem uses for authentication when establishing a PPP connection.
Command
Description
To include the service provider name in the SPD, use the cable telco-return service-provider interface configuration command. To remove the parameter from the SPD, use the no form of this command.
cable telco-return spd spd-number service-provider spd-string
Syntax Description
spd-number Service provider descriptor number for which this parameter is set. Valid range is 1 through 5. spd-string Alphanumeric string that identifies the service provider.
Defaults
No default behavior or values.
Command Modes
Interface configuration
Command History
12.0(4)XI This command was introduced.
Release
Modification
Usage Guidelines
This command sets the Service Provider Name parameter for the specified SPD in the TCD messages.
Examples
The following example sets the service provider name to "san_jose" for SPD 2:
interface cable 6/0 cable telco-return spd 2 service-provider san_jose
Related Commands
Enables telco-return functionality. Indicates the service provider descriptor (SPD) that the telco-return cable modem uses during the initialization process.
Command
Description
To set the number of failed dial-up connections that can occur before the cable modem indicates a connection failure, use the cable telco-return spd threshold interface configuration command. To restore the default value, use the no form of this command.
cable telco-return spd spd-number threshold threshold-number
Syntax Description
spd-number Service provider descriptor number for which this parameter is set. Valid range is 1 through 5. threshold-number Number of dial-up attempts that fail before the cable modem declares a connection failure. Valid range is 1 through 255.
Defaults
The default value is 1.
Command Modes
Interface configuration
Command History
12.0(4)XI This command was introduced.
Release
Modification
Usage Guidelines
This command sets the Connection Threshold parameter for the specified SPD in the TCD messages. A dial-up attempt is considered a connection failure if an answer connection is not made after ten rings. The cable modem continues to try to connect until the connection threshold is reached. If multiple phone numbers are configured using the cable telco-return spd phonenum command, the cable modem dials each phone number until it makes a connection or exceeds the configured threshold.
Examples
The following example sets the connection threshold to 20:
interface cable 6/0 cable telco-return spd 2 threshold 20
Related Commands
Enables telco-return functionality. Sets the number of seconds that the telco-return cable modem waits before disconnecting any inactive upstream telephone connection. Sets the telephone numbers that the telco-return cable modem dials when connecting to the headend's network access server.
Command
Description
To set the username that the telco-return cable modem uses for authentication when establishing a PPP connection with the access server, use the cable telco-return spd username interface configuration command. To restore the default value, use the no form of this command.
cable telco-return spd spd-number username login-string
Syntax Description
spd-number Service provider descriptor number for which this parameter is set. Valid range is 1 through 5. login-string Username that the cable modem uses for authentication during the initialization procedure.
Defaults
The default value is "guest."
Command Modes
Interface configuration
Command History
12.0(4)XI This command was introduced.
Release
Modification
Usage Guidelines
This command sets the Login Username parameter for the specified SPD in the TCD messages.
Examples
The following example sets the username to "sandy" for SPD 3:
interface cable 6/0 cable telco-return spd 3 username sandy
Related Commands
Enables telco-return functionality. Specifies the Login Password parameter in TCD messages. Selects the authentication procedure to use when the telco-return cable modem is establishing a PPP connection.
Command
Description
This section documents new or modified commands. All other commands used with this feature are documented in the Cisco IOS Release 12.1 command references.
To display debug messages for telco-return events, use the debug cable telco-return EXEC command. To disable debugging output, use the no form of this command.
debug cable telco-returnSyntax Description
This command has no arguments or keywords.
Defaults
Debugging for telco-return events is not enabled.
Command History
12.0(4)XI This command was introduced.
Release
Modification
Examples
The following is sample output from the debug cable telco-return and debug cable telco-return msg commands:
01:17:31:Sending TCD message: TLV type = 1 TLV len = 56 Factory default flag: 1 Phone number 1: 9536804 Service provider name:uBR7246 Connection threshold: 10 Username: guest Password: password DHCP authenticate: 1 DHCP server: 1.7.7.7 PPP authentication: 2 Manual dial: 1 Sending TSI message: DS channel IP address: 2.73.2.1 Registration IP address:2.73.2.1 CMTS boot time: 3080626752 DS channel ID: 0 Epoch: 1
Related Commands
Displays the Telephony Channel Descriptor (TCD) and Termination System Information (TSI) messages.
Command
Description
To display the Telephony Channel Descriptor (TCD) and Termination System Information (TSI) messages that are sent downstream to the telco-return cable modems, use the debug cable telco-return msg EXEC command. To disable debugging output, use the no form of this command.
debug cable telco-return msgSyntax Description
This command has no arguments or keywords.
Defaults
TCD and TSI messages are not displayed.
Command History
12.0(4)XI This command was introduced.
Release
Modification
Examples
The following is sample output from the debug cable telco-return msg command:
01:17:31:Sending TCD message: TLV type = 1 TLV len = 56 Factory default flag: 1 Phone number 1: 9536804 Service provider name:uBR7246 Connection threshold: 10 Username: guest Password: password DHCP authenticate: 1 DHCP server: 1.7.7.7 PPP authentication: 2 Manual dial: 1 Sending TSI message: DS channel IP address: 2.73.2.1 Registration IP address:2.73.2.1 CMTS boot time: 3080626752 DS channel ID: 0 Epoch: 1
Related Commands
Displays debug messages for telco-return events.
Command
Description
CHAP---Challenge Handshake Authentication Protocol. Security feature supported on lines using PPP encapsulation that prevents unauthorized access. CHAP does not itself prevent unauthorized access, it merely identifies the remote end. The router or access server then determines whether that user is allowed access.
DHCP---Dynamic Host Configuration Protocol. Provides a mechanism for allocating IP addresses dynamically so that addresses can be reused when hosts no longer need them.
DOCSIS---Data-over-Cable Service Interface Specifications. Defines technical specifications for equipment at both subscriber locations and cable operators' headends. Adoption of DOCSIS will accelerate deployment of data-over-cable services and ensure interoperability of equipment throughout system operators' infrastructures.
headend---Central distribution point for a CATV system. Video signals are received here from satellite (either co-located or remote), frequency converted to the appropriate channels, combined with locally originate signals, and rebroadcast onto the HFC plant. For a CATV data system, the headend is the typical place to link between the HFC system and any external data networks.
PAP---Password Authentication Protocol. Authentication protocol that allows PPP peers to authenticate one another. The remote router attempting to connect to the local router is required to send an authentication request. Unlike CHAP, PAP passes the password and host name or username in the clear (unencrypted). PAP does not itself prevent unauthorized access, but merely identifies the remote end. The router or access server then determines if that user is allowed access. PAP is supported only on PPP lines.
PPP---Point-to-Point Protocol. Successor to SLIP that provides router-to-router and host-to-network connections over synchronous and asynchronous circuits. Whereas SLIP was designed to work with IP, PPP was designed to work with several network layer protocols, such as IP, IPX, and ARA. PPP also has built-in security mechanisms, such as CHAP and PAP.
PSTN---Public Switched Telephone Network. General term referring to the variety of telephone networks and services in place worldwide. Sometimes called plain old telephone service (POTS) .
RF---radio frequency. Generic term referring to frequencies that correspond to radio transmissions. Cable TV and broadband networks use RF technology.
SPD---Service Provider Descriptor. Set of configuration attributes that are used by the telco-return cable modem to initiate a telephone call when the cable modem is first powered on or is reset to its factory default. Each TCD message contains at least one and as many as five SPDs.
TCD---Telephony Channel Descriptor.
TSI---Termination System Information. TSI messages are transmitted by the headend router at periodic intervals to report cable modem termination system (CMTS) status information to the downstream cable modems.
Posted: Sun Jun 11 19:00:05 PDT 2000
Copyright 1989 - 2000©Cisco Systems Inc.