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Table of Contents

Configuring the Multiservice Route Processor

Configuring the Multiservice Route Processor

This chapter explains how to configure the multiservice route processor (MRP) and contains the following sections:


Note   This guide describes the use of IOS commands that have been created or changed for use with the MRP that supports IOS Release 12.1.(4)T. The complete IOS Release 12.1 documentation is available through CCO by selecting Service and Support > Technical Documents > Documentation Home Page > Cisco IOS Software Configuration > Cisco IOS Release 12.1.


Note   For default settings on the MRP and more information on the commands described in this chapter, refer to the Cisco ICS 7750 Command Reference.

MRP Overview

The MRP is a voice-and-data-capable router that can carry voice and data traffic over an IP network and can link small-to-medium-size remote Ethernet LANs to central-offices (COs) LANs over different types of WAN links.

Features

The MRP has the following main features:

Supported WICs, VICs, and VWICs

Table 5-1 lists the WICs, VICs, and VWICs supported by the MRP. A VWIC functions both as a WIC and a VIC. Each VWIC can be used for voice or data, but both cannot be configured on a single T1. However, you can have voice on one T1 and data on another T1.


Table 5-1: Supported WICs, VICs, and VWICs
Card Description Voice or Data Abbreviated Name

1-port serial

Data

1T WIC

2-port serial

Data

2T WIC

2-port asynchronous/synchronous serial

Data

2A/S WIC

1-port ISDN1 BRI2 S/T

Data

1B-ST WIC

1-port ISDN BRI U

Data

1B-U WIC

1-port 56/64-kbps DSU/CSU3

Data

1DSU-56K4 WIC

1-port T1/FT1

Data

1DSU-T1 WIC

2-port FXS4 voice/fax interface

Voice

2FXS VIC

2-port FXO5 voice/fax interface

Voice

2FXO VIC

2-port E&M6 voice/fax interface

Voice

2E&M VIC

1-port T1 multiflex trunk interface

Voice and data

1MFT-T1 VWIC

2-port T1 multiflex trunk interface

Voice and data

2MFT-T1 VWIC

1ISDN = Integrated Services Digital Network
2BRI = Basic Rate Interface
3DSU/CSU = Data service unit/channel service unit
4FXS = Foreign Exchange Station
5FXO = Foreign Exchange Office
6E&M = Receive and transmit (or ear and mouth).

Combination Guidelines for WICs, VICs, and VWICs

Table 5-2 contains the combination guidelines for installing WIC, VIC, and VWIC cards in the MRP. Cards that can be installed in Slot 0 are listed across the top of the table. Cards that can be installed in Slot 1 are listed in the left column.


Table 5-2: Allowed WIC, VIC, and VWIC Combinations (for MRP Card)
1B-ST WIC 1B-U WIC 1T WIC 1DSU-56K4 WIC 1DSU-T1 WIC 2T WIC 2A/S WIC 2MFT-T1 VWIC-
Two
Voice
2MFT-T1 VWIC-
One Voice, One Data
1MFT-T1 VWIC-Voice 1MFT-T1 VWIC -Data FXS, FXO,
E&M VICs
1B-ST WIC 1B-U WIC

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

1T WIC 1DSU-56K4 WIC 1DSU-T1 WIC

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

2T WIC 2A/S WIC

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

2MFT-T1 VWIC
Two Voice1

Yes

Yes

Yes

No

No

No

Yes

Yes

2MFT-T1 VWIC
One Voice, One Data2

Yes

Yes

Yes

No

No

Yes

No

Yes

1MFT-T1 VWIC-Voice

Yes

Yes

Yes

No

Yes

Yes

Yes

Yes

1MFT-T1 VWIC-Data

Yes

Yes

Yes

Yes

No

Yes

No

Yes

1Even though the MRP can configure both ports on a 2MFT-T1 for voice, it can only make 24 simultaneous calls.
2The MRP does not support 2MFT-T1 VWIC for two T1 data channels.

CODEC / DSP Overview

The MRP supports two CODECs, G.729a and G.711, for Voice over IP (VoIP) calls. The default is G.711. Each digital signal processor (DSP) can handle a combination of G.711 and G.729a calls.

DSP Groups

The MRP handles the calls based on the grouping of the DSPs. The DSPs are located on the packet voice data module (PVDM). There can be up to five DSPs on a single PVDM. Each PVDM corresponds to one DSP group.The MRP has two PVDM slots and therefore can have a maximum of two DSP groups. Each DSP group serves either an analog port or a T1 port on the VIC. Therefore, one analog VIC and one T1 VIC make up two groups and two T1 VICs with two different clock sources also make up two groups.

DSP Group Serving a T1 Port

Each DSP group serving a T1 port can support as many DSPs as there are in the PVDM.

A DSP has a maximum capacity of 100 MIPS to handle a particular number of simultaneous calls. One G.729a call requires 25 MIPS and one G.711 call requires 12.5 MIPS. The number of calls on a DSP is determined by the total used MIPS reaching 100 on that DSP. The DSP resource manager rejects the call if it cannot find a DSP with required unused MIPS for the selected CODEC.

The following table lists some of the scenarios of the number of calls supported on a single DSP depending on the CODEC used:


Table 5-3: CODEC/DSP Call Scenarios
Scenarios Calls per DSP CODECs MIPS per session MIPS Required Call Status

1

4

G.729a

25

25 x 4 = 100

4 calls accepted

2

8

G,711

12.5

12.5 x 8 = 100

8 calls accepted

3

4

1

G.729a

G,711

25

12.5

25 x 4 = 100

12.5 x 1 = 12.5

1 call rejected

Some of the combinations of calls that can be used on a single DSP are as follows:


Table 5-4: Combinations of Number of CODEC Calls on a Single DSP
G.711 Calls G.729a Calls

2

3

4

2

6

1

DSP Group Serving Analog Port

Each DSP group serving analog ports needs one DSP per VIC. Therefore, two analog VICs need two DSPs. Each DSP in this case can handle two calls that can be either a G.711, G.729a, or a fax relay.

Restrictions for CLI Usage


Caution The user is strongly recommended to use only the Cisco ICS 7700 System Manager (also referred to as System Manager) GUI interface to define and manipulate the MRP configurations that are supported by this interface. It is possible for a user with sufficient knowledge to change configurations by direct interaction with the system components through the CLI. However, if there are problems due to CLI configuration, you will not be able to use the System Manager to recover.

It is also recommended that the following list of tasks should not be done through the CLI, because they are configured through the System Manager and might conflict with its configurations:

Accessing the MRP CLI

To configure the MRP through the CLI, you must access the MRP through the system alarm processor (SAP). For more information on how to get the CLI prompt on the MRP, refer to "Accessing the System."

Saving Configuration Changes

To prevent the loss of the MRP configuration, save the running-config file to the startup-config file by following these steps:

Command Purpose

Step 1 

MRP> enable

Password: password

MRP# 

Enter enable mode.

Enter the password.

You have entered enable mode when the prompt changes to MRP#.

Step 2 

MRP# copy running-config startup-config

Save the configuration changes to the startup-config file so that they are not lost during resets, power cycles, or power outages.

Configuring Fast Ethernet Interfaces

To configure a Fast Ethernet interface, use either the Cisco ICS 7700 System Manager provided with the system or the configuration mode (manual configuration). In this mode, enter IOS commands at the MRP prompt.

This section describes basic configuration, including enabling the interface and specifying IP routing. Depending on your own requirements and the protocols you plan to route, you might also need to enter other configuration commands.

Before you begin configuring the interfaces, make sure you do the following:


Note   It is recommended not to change the pre-configured Fast Ethernet interfaces because the change might conflict with the System Manager configurations.

Command Purpose

Step 1 

MRP> enable

Password: password

MRP# 

Enter enable mode.

Enter the password.

You have entered enable mode when the prompt changes to MRP#.

Step 2 

MRP# configure terminal

Enter configuration commands, one per line. End

with CNTL/Z.

MRP(config)#

Enter global configuration mode. You have entered global configuration mode when the prompt changes to MRP(config)#.

Step 3 

MRP# ip routing

Enable routing protocols as required for your global configuration. This example uses IP routing.

Step 4 

MRP(config)# interface fastethernet 0/0

MRP(config-if)#

Enter interface configuration mode. You have entered interface configuration mode when the prompt changes to MRP(config-if)#.

Step 5 

MRP(config-if)# ip address 172.16.74.3 255.255.255.0

Assign an IP address and subnet mask to the interface.

Step 6 

MRP(config-if)# exit

Exit back to global configuration mode.

Repeat Step 4 through Step 6 if your MRP has more than one interface that you need to configure.

Step 7 

MRP(config-if)# Ctrl-z

MRP#

When you finish configuring interfaces, return to enable mode.

Configuring WAN Interfaces

This section contains the following subsections:

Configuring Asynchronous/Synchronous Serial WICs

You can configure the serial interfaces on your asynchronous/synchronous serial WIC manually by entering IOS commands on the command line in configuration mode.

Before you begin configuring the interfaces, make sure you do the following:

Command Purpose

Step 1 

MRP> enable

Password:password

MRP# 

Enter enable mode.

Enter the password.

You have entered enable mode when the prompt changes to MRP#.

Step 2 

MRP# configure terminal

Enter configuration commands, one per line. End

with CNTL/Z.

MRP(config)#

Enter global configuration mode. You have entered global configuration mode when the prompt changes to MRP(config)#.

Step 3 

MRP# ip routing

Enable routing protocols as required for your global configuration. This example uses IP routing.

Step 4 

MRP(config)# interface serial 0

MRP(config-if)#

Enter the interface configuration mode. You have entered interface configuration mode when the prompt changes to MRP(config-if)#.

Step 5 

MRP(config-if)# ip address 172.16.74.1 255.255.255.0

Assign the IP address and subnet mask to the interface.

Step 6 

MRP(config-if)# physical-layer async

All serial ports are initially configured as synchronous. Enter this command if you want to configure the port as asynchronous.

Step 7 

MRP(config-if)# async mode dedicated

MRP(config-if)# async default routing

Configure asynchronous parameters according to your needs.

Step 8 

MRP(config-if)# line async#

Configure the asynchronous line setting.

Step 9 

MRP(config-if)# half-duplex timer dcd-drop-delay 100

Specify the time that the interface waits in controlled carrier mode. See Table 5-5 for a list of half-duplex timer commands.

Step 10 

MRP(config-if)# clockrate 7200

To use a port in DCE mode, connect a DCE cable and set the internal transmit clock signal (TXC) speed in bits per second. See Table 5-6 through Table 5-8 for a list of clock rate settings for your specific interface. (For ports used in DTE mode, the MRP automatically uses the external timing signal.)

Step 11 

MRP(config-if)# dce-terminal-timing-enable

When a port is operating in DCE mode, the default operation is for the DCE to send serial clock transmit (SCT) and serial clock receive (SCR) clock signals to the DTE, and for the DTE to return a serial clock transmit external (SCTE) signal to the DCE.

If the DTE does not return SCTE, enter this command to configure the DCE port to use its own clock signal.

Step 12 

MRP(config-if)# invert-txc

MRPs that use long cables might experience high error rates when operating at higher transmission speeds, because the clock and data signals can shift out of phase.

If a DCE port is reporting a high number of error packets, inverting the clock using this command can often correct the shift.

Step 13 

MRP(config-if)# exit

Exit back to global configuration mode.

Repeat Step 4 through Step 14 if your MRP has more that one serial interface that you need to configure.

Step 14 

MRP(config)# Ctrl-z

MRP#

When you finish configuring interfaces, return to enable mode.

Step 15 

MRP#copy running-config startup-config

Save the configuration changes to the startup-config file so that they are not lost during resets, power cycles, or power outages.

Table 5-5 shows a list of half-duplex timer commands.


Table 5-5: Half-Duplex Timer Commands
Timer Syntax Default Setting (Milliseconds)

CTS delay1

half-duplex timer cts-delay

100

CTS drop timeout

half-duplex timer cts-drop-timeout

5000

DCD drop delay

half-duplex timer dcd-drop-delay

100

DCD transmission start delay

half-duplex timer dcd-txstart-delay

100

RTS2 drop delay

half-duplex timer rts-drop-delay

100

RTS timeout

half-duplex timer rts-timeout

2000

Transmit delay

half-duplex timer transmit-delay

0

1CTS = Clear To Send
2RTS = Request To Send

Table 5-6 through Table 5-8 show lists of clock rate settings for your specific interface.


Table 5-6: Clock Rate Settings for 1-Port/2-Port Serial WAN Interface Card in Synchronous Mode

1200 bps

38400 bps

148000 bps

2400 bps

56000 bps

500000 bps

4800 bps

57600 bps

800000 bps

9600 bps

64000 bps

1000000 bps

14400 bps

72000 bps

1300000 bps

19200 bps

115200 bps

2000000 bps

28800 bps

125000 bps

4000000 bps

32000 bps

128000 bps

148000 bps


Table 5-7: Clock Rate Settings for 1-Port/2-Port Serial WAN Interface Card in Asynchronous Mode

1200 bps

28800 bps

72000 bps

2400 bps

32000 bps

115200 bps

4800 bps

38400 bps

125000 bps

9600 bps

56000 bps

128000 bps

14400 bps

57600 bps

19200 bps

64000 bps


Table 5-8: Clock Rate Settings for 2-Port Asynchronous/Synchronous Serial WAN Interface Card

1200 bps

28800 bps

72000 bps

2400 bps

32000 bps

115200 bps

4800 bps

38400 bps

125000 bps

9600 bps

56000 bps

128000 bps

14400 bps

57600 bps

19200 bps

64000 bps


Note   To prevent the loss of MRP configuration, refer to the "Saving Configuration Changes" section in this chapter.

Configuring ISDN BRI WICs

You can configure the interfaces on your BRI WAN interface card manually by entering IOS commands on the command line in configuration mode.

Before you begin configuring the interfaces, make sure you do the following:

Command Purpose

Step 1 

MRP> enable

Password: password

MRP# 

Enter enable mode.

Enter the password.

You have entered enable mode when the prompt changes to MRP#.

Step 2 

MRP# configure terminal

Enter configuration commands, one per line. End with CNTL/Z.

MRP(config)#

Enter global configuration mode. You have entered global configuration mode when the prompt changes to MRP(config)#.

Step 3 

MRP(config)# isdn switch-type basic-5ess

Enter an ISDN switch type. See Table 5-8 for a list of ISDN switch types.


Note   Switch types configured in interface configuration mode override this setting for the configured interface.

Step 4 

MRP(config)# ip routing

Enable routing protocols as required for your global configuration. This example uses IP routing.

Step 5 

MRP(config)# interface bri 0/0

MRP(config-if)#

Enter the interface configuration mode. You have entered interface configuration mode when the prompt changes to MRP(config-if)#.

Step 6 

MRP(config-if)# ip address 172.16.74.2 255.255.255.0

MRP(config-if)# isdn switch-type basic-5ess

Assign the IP address and subnet mask to the interface.

If you are configuring this interface for voice, enter the switch type instead of an IP address.

Step 7 

MRP(config-if)# exit

Exit back to global configuration mode.

Repeat Step 5 through Step 7 if your MRP has more than one BRI interface that you need to configure.

Step 8 

MRP(config-if)# memory-size iomem 40

By default, the card allocates 25 percent of DRAM to shared memory (used for data transmitted or received by network modules and WAN interface cards). If your card includes 16 or more ISDN BRI interfaces, you must increase the amount of shared memory by entering the memory-size iomem command. This example increases shared memory from 25 percent to
40 percent.

Step 9 

MRP(config)# Ctrl-z

MRP#

When you finish configuring interfaces, return to enable mode.

Step 10 

MRP#copy running-config startup-config

Save the configuration changes to the startup-config file so that they are not lost during resets, power cycles, or power outages.

Table 5-9 shows a list of ISDN switch types for North America.


Table 5-9: ISDN Switch Types
ISDN Switch Type Description

basic-5ess

AT&T basic rate switches

basic-dms100

NT DMS-100 basic rate switches

basic-nil1

National ISDN-1 switches

Configuring ISDN BRI Lines

Before using an MRP with an ISDN BRI interface, you must order a correctly configured ISDN BRI line from your local telecommunications service provider.

The ordering process varies from provider to provider and from country to country; however, here are some general guidelines:

ISDN BRI Provisioning by Switch Type

ISDN BRI provisioning refers to the types of services provided by the ISDN BRI line. Although provisioning is performed by your ISDN BRI service provider, you must tell the provider what you want. Table 5-10 lists the provisioning you should order for your MRP.


Table 5-10: ISDN Provisioning by Switch Type
Switch Type Provisioning

5ESS Custom BRI

For data only:

2 B channels for data

Point to point

Terminal type = E

1 directory number (DN) assigned by service provider

MTERM = 1

Request delivery of calling line ID on Centrex lines

Set speed for ISDN calls to 56 kbps outside local exchange

5ESS National ISDN (NI-1) BRI

Terminal type = A

2 B channels

2 directory numbers assigned by service provider

2 SPIDs required, assigned by service provider

Set speed for ISDN calls to 56 kbps outside local exchange

Directory number 1 can hunt to directory number 2

DMS-100 BRI

2 B channels

2 directory numbers assigned by service provider

2 SPIDs required, assigned by service provider

Functional signaling

Dynamic terminal endpoint identifier (TEI) assignment

Maximum number of keys = 64

Release key = no, or key number = no

Ringing indicator = no

EKTS = no

PVC = 2

Request delivery of calling line ID on Centrex lines

Set speed for ISDN calls to 56 kbps outside local exchange

Directory number 1 can hunt to directory number 2

Defining ISDN Service Profile Identifiers

Some service providers assign service profile identifiers (SPIDs) to define the services to which an ISDN device subscribes. If your service provider requires SPIDs, your ISDN device cannot place or receive calls until it sends a valid SPID to the service provider when initializing the connection. A SPID is usually a 7-digit telephone number plus some optional numbers, but service providers might use different numbering schemes. SPIDs have significance at the local access ISDN interface only; remote MRPs are never sent the SPID.

Currently, only DMS-100 and NI-1 switch types require SPIDs. Two SPIDs are assigned for the DMS-100 switch type, one for each B channel. The AT&T 5ESS switch type might support SPIDs, but Cisco recommends that you set up that ISDN service without SPIDs.

If your service provider assigns you SPIDs, you must define these SPIDs on the MRP. To define SPIDs and the local directory number (LDN) on the MRP for both ISDN BRI B channels, use the following isdn spid commands:

MRP (config-if)# isdn spid1 spid-number [ldn]

MRP (config-if)# isdn spid2 spid-number [ldn]


Note   Although the LDN is an optional parameter in the command, you might need to enter it so that the MRP can answer calls made to the second directory number.

For further information on configuring ISDN, see the chapters "Configuring ISDN" and "Configuring DDR" in the Wide-Area Networking Configuration Guide for the Cisco IOS Release 12.0.

Configuring T1 (FT1) WICs

The 1-port T1 and fractional (FT1) WICs includes an integrated data service unit /channel service unit (DSU/CSU) and can be configured either for full T1 service at 1.544 Mbps or for fractionalized T1 service. You can configure the interfaces on your T1 WICs manually by entering IOS commands on the command line. This method, called configuration mode, provides the greatest power and flexibility.

Before you begin configuring the interfaces, make sure you do the following:

Default Configuration

The IOS software provides the following default configuration for DSU/CSU- and T1-specific parameters:

service-module t1 clock source line

service-module t1 data-coding normal

service-module t1 timeslots all speed 64

service-module t1 framing esf

service-module t1 lbo none

service-module t1 linecode b8zs

no service-module t1 remote-alarm-enable

service-module t1 remote-loopback

no service-module t1 fdl

 

To view the current configuration, enter the show service-module serial slot/port command. For further information about these commands, refer to the Cisco IOS configuration guides and command references.

Use the following procedure to configure a new T1/FT1 interface or to change the configuration of an existing interface:

Command Purpose

Step 1 

MRP> enable

Password: password

MRP# 

Enter enable mode.

Enter the password.

You have entered enable mode when the prompt changes to MRP#.

Step 2 

MRP# configure terminal

Enter configuration commands, one per line. End

with CNTL/Z.

MRP(config)#

Enter global configuration mode. You have entered global configuration mode when the prompt changes to MRP(config)#.

Step 3 

MRP# ip routing

Enable routing protocols as required for your global configuration. This example uses IP routing.

Step 4 

MRP(config)# interface serial 0/0

MRP(config-if)#

Enter the interface configuration mode. You have entered interface configuration mode when the prompt changes to MRP(config-if)#.

Step 5 

MRP(config-if)# ip address 172.16.74.2 255.255.255.0

Assign the IP address and subnet mask to the interface.

Step 6 

MRP(config-if)# service-module t1 framing {esf | sf}

MRP(config-if)# service-module t1 linecode {b8zs | ami}

Enter the framing type and linecode type. In this example, the framing type specified is sf (Superframe) and the linecode specified is ami.

Step 7 

MRP(config-if)# service-module t1 timeslots 1-20 speed 64

If you are using fractional T1 service, enter the time slot range and speed. In this example, the time slot range specified is from 1 to 20, and the speed specified is 64 kbps.

Step 8 

MRP(config-if)# exit

Exit back to global configuration mode.

Repeat Step 4 through Step 8 if your MRP has more than one interface that you need to configure.

Step 9 

MRP(config)# Ctrl-z

MRP#

When you finish configuring interfaces, return to enable mode.

Step 10 

MRP#copy running-config startup-config

Save the configuration changes to the startup-config file so that they are not lost during resets, power cycles, or power outages.


Note   To prevent the loss of MRP configuration, refer to the "Saving Configuration Changes" section in this chapter.

Configuring MFT-T1 WICs

Configure the multiflex trunk interface (MFT-T1) card as a WIC (data). In the WIC mode, MRP treats the T1 as a single serial interface for data up to 1.544 Mbps. You can specify the number of channels (up to 24) for this connection. On a data T1 you can configure only one channelized group. The rest of the channels are simply not used.

The MRP supports the following T1 configurations:

To configure a T1 multiflex trunk interface, use the Cisco ICS 7700 System Manager available on your system or use configuration mode (manual configuration). In this mode, you enter IOS commands at the MRP prompt.

This section describes basic configuration, including enabling the interface and specifying IP routing. Depending on your own requirements and the protocols you plan to route, you might also need to enter other configuration commands.

Before you begin configuring the interfaces, make sure you do the following:

Configuring TDM Clock

Digital T1 interfaces require not only that you set timing, but that you consider the source of the timers. You must configure the tdm clock to specify the clock source. You can specify up to two external clock sources for each MRP. This means that only two of the T1 ports can use line as the clock source. The clock source is selected via the tdm clock global configuration command.

For detailed commands and tasks to configure the tdm clock, refer to the "Configuring TDM Clock" section. For default tdm clock values, refer to the "Default TDM Clock" section.

Scenarios of TDM Clocking

Refer to the "TDM Clocking Scenarios" section, which describes the basic timing scenarios that can occur when a digital T1 interface is connected to a PBX, CO, or both.

Configuring MFT-T1 Interfaces

Use the following procedure to configure a new T1 interface or to change the configuration of an existing interface.

Command Purpose

Step 1 

MRP> enable

Password: password

MRP# 

Enter enable mode.

Enter the password.

You have entered enable mode when the prompt changes to MRP#.

Step 2 

MRP# configure terminal

Enter configuration commands, one per line. End

with CNTL/Z.

MRP(config)#

Enter global configuration mode. You have entered global configuration mode when the prompt changes to MRP(config)#.

Step 3 

MRP# ip routing

Enable routing protocols as required for your global configuration. This example uses IP routing.

Step 4 

MRP(config)# controller t1 1/0

Select the T1 interface to configure. This example configures a T1 interface in slot 1 and port 0.

Step 5 

MRP(config-controller)# framing {esf | sf}

Specify the framing type. The default is esf.

Step 6 

MRP(config-controller)# linecode {b8zs | ami}

Specify the line code format. The default is b8zs.

Step 7 

MRP(config-controller)# channel-group X timeslots 1-24

Specify the channel group and time slots to be mapped. For multiflex trunk interfaces, only one channel group can be configured.

Step 8 

MRP(config-controller)# interface serial 1/0:0

Configure each channel group as a virtual serial interface. Specify the T1 interface, port number, and channel group to modify.

Step 9 

MRP(config-if)# ip address 10.1.15.1 255.255.255.0

Assign an IP address and subnet mask to the interface.

Step 10 

MRP(config-if)# exit

Exit back to global configuration mode.

Return to Step 4 if your MRP has more than one T1 interface that you need to configure.

Step 11 

MRP(config-if)# Ctrl-z

MRP#

When you finish configuring interfaces, return to enable mode.

Step 12 

MRP#copy running-config startup-config

Save the configuration changes to the startup-config file so that they are not lost during resets, power cycles, or power outages.


Note   To prevent the loss of MRP configuration, refer to the "Saving Configuration Changes" section in this chapter.

Configuring Voice over IP

This section contains the following subsections:

Voice-Ports Overview

The MRP provides both analog and digital voice ports for its implementation of Voice over IP (VoIP). The type of signaling associated with these analog voice ports depends on the VIC installed in the device.

You can install either a VIC or a VWIC in the MRP to make voice-related calls through the network. A VIC connects the MRP directly to a regular analog phone, fax, or to a PBX. Alternatively, a VWIC enables 24 channels or this number of simultaneous calls incoming or outgoing on the network. This provides a much higher density than with the VIC, which has only two ports per MRP. VWIC also provides the flexibility to combine channels to form channel groups with the same characteristics.

Each VIC is specific to a particular signaling type; therefore, VICs determine the type of signaling for the voice ports. Voice-port commands define the characteristics associated with a particular voice-port signaling type.

The voice ports support four basic voice signaling types:

Figure 5-1 shows how to connect the VICs to the network.


Figure 5-1:
Connecting VICs to the Network


Configuring Analog Voice Ports

This section contains the following subsections:

Configuring FXS Interfaces

This section explains how to configure ports on FXS VICs that connect directly to a standard telephone, fax machine, or similar device.

Figure 5-2 shows a basic voice network. A small business uses a MRP card (named West) to provide telephone and fax connections among employees in its office. Two of these telephones are connected to an FXS VIC port in the West MRP.


Figure 5-2: Basic Voice Network (West MRP)



Note   You can name your MRP by using the global configuration hostname command.

Table 5-11 lists telephone numbers and voice ports for the West MRP.


Table 5-11: West MRP Telephone Numbers and Voice Ports
Telephone Number Voice Port

408 555-3737

0/0

408 555-4141

0/1


Note   If your MRP is configured with two VICs, a total of four telephones and fax machines can be connected to it. As the MRP has only two slots, you need to replace one VIC with a WIC to provide an interface for IP connectivity to the WAN and for data traffic. To accommodate more than four voice devices, you need to add more MRPs or use an E&M VIC and a local PBX, rather than connecting every telephone to its own FXS VIC.

Local Dial Peers

To route a received voice call to the right destination, the MRP needs to know which telephone number belongs to each voice port. For instance, if a call comes in for 408 555-3737, the MRP needs to know that this telephone is connected to voice port 0/0 (as shown in Figure 5-2.) In other words, the MRP needs to know the information in Table 5-11.

To hold this information, IOS software uses objects called dial peers. A telephone number, a voice port, and other call parameters are tied together by associating them all with the same dial peer. Configuring dial peers is similar to configuring static IP routes—you are telling the MRP what path to follow to route the call. All voice technologies use dial peers to define the characteristics associated with a call leg. A call leg is a segment of a call path; for example, segments occur between a telephone and an MRP, an MRP and a network, an MRP and a PBX, or an MRP and the PSTN. Each call leg corresponds to a dial peer.

Dial peers are identified by numbers, but they are usually referred to as tags to avoid confusion with telephone numbers. Dial-peer tags are arbitrary integers that can range from 1 to 231-1(2147483647). Within the allowed range, you can choose any dial-peer tag that is convenient or makes sense to you. Dial peers on the same MRP must have unique tags, but you can reuse the tags on other MRPs.

Table 5-12 assigns a dial-peer tag to each telephone number and its associated voice port on the West MRP. This type of dial peer is called a POTS dial peer or a local dial peer. The term POTS (plain old telephone service) means that the dial peer associates a physical voice port with a local telephone device. (VoIP dial peer is explained in the section "Calling Between MRPs" later in this guide.)


Table 5-12: West MRP Local Dial Peers
Telephone Number Voice Port Dial-Peer Tag

408 555-3737

0/0

401

408 555-4141

0/1

402

You should construct a table similar to Table 5-12 for your own MRPs, assigning your own telephone numbers and dial-peer tags.


Note   The telephone numbers used in this guide are only examples and are invalid for public use in the United States. When you configure your network, be sure to substitute your own telephone numbers.

To configure the MRP with the dial-peer information in Table 5-12, enter the following global configuration commands:

Command Purpose

Step 1 

West> enable

 
Password: password
 
West #

Enter enable mode.

Enter the password.

You have entered enable mode when the prompt changes to West #

Step 2 

West> configure terminal

West(config)#

Enter global configuration mode. You have entered global configuration mode when the prompt changes to West(config)#.

Enter configuration commands, one per line. End

with CNTL/Z.

Step 3 

West (config)# dial-peer voice 401 pots

Enter dial-peer configuration mode.

Step 4 

West (config-dial-peer)# destination-pattern 14085553737

Define the destination telephone number associated with the POTS dial peer.

Step 5 

West (config-dial-peer)# port 0/0

Enter the port and slot number associated with this POTS dial peer.

Step 6 

West (config) # dial-peer voice 402 pots

Enter dial-peer configuration mode.

Step 7 

West (config-dial-peer)# destination-pattern 14085554141

Define the destination telephone number associated with the POTS dial peer.

Step 8 

West (config-dial-peer)# port 0/1

Enter the port and slot number associated with this POTS dial peer.

Step 9 

West (config-dial-peer)# exit

Return to configuration mode.

These commands are summarized in Figure 5-3.


Figure 5-3: West MRP Configured for Local Dial Peers


The dial-peer command always takes the argument voice. The number following it is the dial-peer tag, and pots is the type of dial peer.

Cisco IOS software refers to a telephone number as a destination pattern because it is the destination for an incoming or outgoing call. Enter these numbers with the destination-pattern command. A destination pattern can include asterisks (*) and pound signs (#) from the telephone keypad, and commas (,) and periods (.), which have special meanings. Parentheses ( () ), hyphens (-), slashes (/), and spaces ( ), which are often used to make telephone numbers easier for humans to read are not allowed.

Notice that the commands in the examples puts the prefix 1 (used in the United States to indicate a long-distance number) and an area code in front of the remaining numbers to complete the destination pattern. You need to include similar codes for your country if the VoIP equipment needs to establish a connection to the PSTN.


Note   The IOS software does not check the validity of the telephone number. It accepts any string of permitted characters as a valid number.

The business that owns the West MRP also has a branch office in the East. Figure 5-4 shows the East office network, and Table 5-13 lists the phone numbers, voice ports, and dial-peer tags for this office.


Figure 5-4: Basic Voice Network (East MRP)



Table 5-13: East MRP Local Dial Peers
Telephone Number Destination Pattern Voice Port Dial-Peer Tag

919 555-8282

19195558282

1/0

901

919 555-9595

19195559595

1/1

902

Enter the following commands to configure the local ports on the East MRP with the dial-peer information in Table 5-13:

Command Purpose

Step 1 

East (config)# dial-peer voice 901 pots

Enter dial-peer configuration mode

Step 2 

East (config-dial-peer)# destination-pattern 19195558282

Define the destination telephone number associated with the POTS dial peer.

Step 3 

East (config-dial-peer)# port 1/0

Enter the port/slot number associated with this POTS dial peer.

Step 4 

East (config)# dial-peer voice 902 pots

Enter dial-peer configuration mode

Step 5 

East (config-dial-peer)# destination-pattern 19195559595

Define the destination telephone number associated with the POTS dial peer.

Step 6 

East (config-dial-peer)# port 1/1

Enter the port and slot number associated with this POTS dial peer.

Step 7 

East (config-dial-peer)# exit

Return to configuration mode.

These commands are summarized in Figure 5-5.


Figure 5-5: East MRP Configured for Local Dial Peers


Checking the Configuration

If you configured POTS dial peers on your MRP by following these examples, you can place calls between telephones connected to the same MRP. You can also use the show dial-peer voice command to verify that the data you configured is correct.


Note   If the voice port is offline, use the interface configuration no shutdown command to enable it.


Note   Although placing calls directly between ports on the same MRP helps to verify your configuration, it is not recommended for general telecommunications use.

Calling Between MRPs

To enable the West and East offices to send voice traffic to each other over the same IP network they use for data traffic, use a WIC on each MRP to provide a connection to the IP network as shown in Figure 5-6.


Figure 5-6: IP Connection Between MRPs


Look at the connection between the West MRP and the IP network. This connection does not include a voice port or an attached telephone—it leads from a WAN interface to a remote destination somewhere on the IP network. IP MRPs know how to locate IP addresses on the network, but they do not know how to locate telephone numbers. To route an outgoing voice call over this connection, the West MRP has to associate a telephone number in the East office with the IP address of the East MRP.

Table 5-14 assigns a dial-peer tag to each telephone number and its associated IP address on the West MRP. This type of dial peer is called a remote dial peer or VoIP dial peer. (Remember, the dial-peer tags are arbitrary.) The term VoIP means that the dial peer associates a telephone number with an IP address.


Table 5-14: West MRP Remote Dial Peers
Remote Location Telephone Number Destination Pattern IP Address Dial-Peer Tag

East

919 555-8282

19195558282

192.168.11.3

501

East

919 555-9595

19195559595

192.168.11.3

502

Create a VoIP dial peer on the West MRP for every telephone on the East MRP, all associated with the same IP address. But it is much easier to use periods as wildcards, as shown in Table 5-15.


Table 5-15: West MRP Remote Dial Peers with Wildcards
Remote Location Telephone Number Destination Pattern IP Address Dial-Peer Tag

East

919 555-xxxx

1919555....

192.168.11.3

501

Construct a table similar to Table 5-15 for your own MRPs, assigning your own telephone numbers, IP addresses, and dial-peer tags.


Note   The IP addresses shown in this guide are meant only as examples. When you configure your network, be sure to substitute your own IP addresses.

Enter the following information on the West MRP to create the dial-peer configuration given in Table 5-15:

Command Purpose

Step 1 

West (config)# dial-peer voice 501 voip

Enter dial-peer configuration mode.

Step 2 

West (config-dial-peer)# destination-pattern 1919555....

Define the destination telephone number associated with the POTS dial peer.

Step 3 

West (config-dial-peer)# session target ipv4:192.168.11.3

Specify a destination IP address for this dial peer.

IOS software describes the remote network as the session target. This command is followed by the IP address of the remote MRP. The prefix ipv4 means IP version 4. Alternatively, you can use the prefix dns followed by the Domain Name System (DNS) name as follows:

West(config-dial-peer)# session target dns:voice.eastMRP.com

 

Configure a dial peer on each MRP for each telephone number on every other MRP connected to it.

Make things easier by configuring number expansion for East MRP telephone numbers on the West MRP. For details on num-exp command, refer to the "Configuring Number Expansion" section.

West(config)# num-exp 5.... 1919555....

 

Now users can dial a five-digit extension beginning with 5 from a telephone on the West MRP to reach a telephone on the East MRP.

These commands are summarized in Figure 5-7.


Figure 5-7: West MRP Configured for Remote Dial Peers


The West MRP is now configured to send calls to the East MRP.

Table 5-16 shows how to configure the East MRP to send calls to the West MRP.


Table 5-16: East MRP Remote Dial Peers with Wildcards
Remote Location Telephone Number IP Address Dial-Peer Tag

West

408 555-xxxx

192.168.19.27

801

Enter the following information on the East MRP to create the dial-peer configuration given in Table 5-16:

Command Purpose

Step 1 

East (config)# num-exp 5.... 1408555....

Expand a five-digit extension beginning with numeral 5 by prefixing 140855 to it.

Step 2 

East (config)# dial-peer voice 801 voip

Enter dial-peer configuration mode.

Step 3 

East (config-dial-peer)# destination-pattern 1408555....

Define the destination telephone number associated with the POTS dial peer.

Step 4 

East (config-dial-peer)# session target ipv4:192.168.19.27

Specify a destination IP address for this dial peer.

These commands are summarized in Figure 5-8.


Figure 5-8: East MRP Configured for Remote Dial Peers


Other MRPs on the Network

If the path between endpoints of a voice call runs through intermediate MRPs, configure those MRPs for VoIP traffic, as described in the section "Configuring FXS Interfaces" earlier in this guide.

You need to configure POTS or VoIP dial peers on an intermediate MRP only if that MRP also has voice devices attached to it.

Checking the Configuration

If you configured VoIP dial peers on your MRP by following these examples, you can place calls from that MRP to telephones on the remote MRPs (using just the extension if you configured number expansion). If you have trouble placing calls, ping the remote MRP to make sure you have IP connectivity, or use the show dial-peer voice command to verify that the data you configured is correct.


Note   Refer to the section "Configuring Quality of Service" if you need to improve the quality of voice connections.


Note   To prevent the loss of MRP configuration, refer to the "Saving Configuration Changes" section in this chapter.

Configuring FXO Interfaces

FXO interfaces provide a gateway from the VoIP network to the analog PSTN or to a PBX that does not support E&M signaling so that users can reach telephones and fax machines outside the VoIP network. Figure 5-9 shows a typical FXO gateway attached to the West MRP.


Figure 5-9: FXO Gateway to PSTN


To create a POTS dial peer for an FXS interface as explained earlier, you enter the complete telephone number of the attached telephone as the destination pattern for incoming calls. However, to create a POTS dial peer for an FXO interface, the destination pattern refers to outgoing calls, and you can include wildcards in it because the PSTN performs the switching.

The VoIP feature can also remove digits that you do not want to send to the PSTN. For instance, to dial 9 to reach an outside line (that is, the analog PSTN), enter the following commands:

Command Purpose

Step 1 

West> enable

Password: password

West#

Enter enable mode.

Enter the password.

You have entered enable mode when the prompt changes to West #.

Step 2 

West> configure terminal

West(config)#

Enter global configuration mode. You have entered global configuration mode when the prompt changes to West(config)#.

Enter configuration commands, one per line. End with CNTL/Z.

Step 3 

West (config) # dial-peer voice 201 pots

Enter dial-peer configuration mode.

Step 4 

West (config-dial-peer)# destination-pattern 9

Define the destination telephone number associated with the POTS dial peer.

Step 5 

West (config-dial-peer)# port 0/0

Enter the port/slot number associated with this POTS dial peer.

When you dial 9, the MRP makes a connection to the PSTN through voice port 0/0. The PSTN then provides a dial tone, and any digits you enter on the telephone thereafter are interpreted on the PSTN.

To enable East MRP users to make calls over the West MRP local PSTN, enter the following commands:

Command Purpose

Step 1 

East (config)# dial-peer voice 701 voip

Enter dial-peer configuration mode.

Step 2 

East (config-dial-peer)# destination-pattern 7

Define the destination telephone number associated with the POTS dial peer.

Step 3 

East (config-dial-peer)# session target ipv4:192.168.19.27

Specify a destination IP address for this dial peer.

Step 4 

West (config) # dial-peer voice 601 pots

Enter dial-peer configuration mode.

Step 5 

West (config-dial-peer)# destination-pattern 7

Define the destination telephone number associated with the POTS dial peer.

Step 6 

West (config-dial-peer)# port 0/0

Enter the port and slot number associated with this POTS dial peer.

When you dial 7 on the East MRP, the call is connected to the PSTN on the West MRP. The PSTN then provides a dial tone, and any digits you enter on the telephone thereafter are interpreted on the PSTN.


Note   In this example, West MRP voice port 0/0 has two separate POTS dial peers associated with it. Dial peer 201 matches calls beginning with the digit 9 and handles PSTN calls originating from the West MRP. Dial peer 601 matches calls beginning with the digit 7 and handles calls to the PSTN originating from the East MRP.

Checking the Configuration

If you configured your FXO interface according to this example, you can place outgoing calls over the PSTN. If you have trouble placing calls, use the show voice port command to make sure that the VIC is installed correctly. Use the show dial-peer voice command to make sure that the data you configured is correct, and test the PSTN by connecting a handset directly to the PSTN outlet and placing a call.


Note   Refer to the section "Configuring Quality of Service" if you need to improve the quality of voice connections.


Note   To prevent the loss of MRP configuration, refer to the "Saving Configuration Changes" section in this chapter.

Configuring E&M Interfaces

If you have more than a few voice users at each location, the cost of voice ports and MRPs and the effort needed to configure dial peers for all the combinations of origins and destinations increases rapidly. In this situation, it might be more efficient to use a PBX at each location to switch local traffic and direct incoming calls and then use E&M VICs to connect the PBXs over an IP network.

Figure 5-10 shows a company with two offices, West and East. Each office has a PBX to operate its internal telephone network, and the IP network carries voice traffic between the offices. Each PBX connects to an E&M VIC port in the MRP.


Figure 5-10: Linking PBXs over the IP Network (Local Dial Peers)


To configure E&M voice ports, you need to use the following commands beginning in privileged EXEC mode:

Command
Purpose

dial-type {dtmf | pulse}

Select the appropriate dial type for out-dialing.

signal {wink-start | immediate | delay-dial}

Select the appropriate signal type for this interface.

cptone {australia | brazil | china | finland | france| germany | japan | northamerica | unitedkingdom}

Select the appropriate voice call progress tone for this interface.

operation {2-wire | 4-wire}

Select the appropriate cabling scheme for this voice port.

type {1 | 2 | 3 | 5}

Select the appropriate E&M interface type.

Both PBXs in this example use E&M interface Type 2, with four-wire operation and immediate-start signaling. The values for your configuration depend on your PBX and are available from your telecommunications department or the PBX manufacturer. For more information about E&M interface configuration commands, refer to the "VoIP Commands" chapter of the Cisco 1750 Router Voice-over-IP Configuration Guide.

In this example, West users can dial 5 and then a 4-digit extension to reach telephones in the East Office. East users can dial 5 and then a 4-digit extension to reach telephones in the West office.

The West MRP connects to the PBX through an E&M VIC port 0/0. This port is associated with a POTS dial peer for incoming calls. But you no longer need to associate every telephone number with its own port. Instead, you can configure a local dial peer as if all the West telephones (represented by a wildcard destination pattern) are connected directly to this port, as shown in the following commands:

Command Purpose

Step 1 

West> enable

Password: password

West#

Enter enable mode.

Enter the password.

You have entered enable mode when the prompt changes to West #.

Step 2 

West> configure terminal

West(config)#

Enter global configuration mode. You have entered global configuration mode when the prompt changes to West(config) #.

Enter configuration commands, one per line. End with CNTL/Z.

Step 3 

West (config)# dial-peer voice 111 pots

Enter dial-peer configuration mode.

Step 4 

West (config-dial-peer)# destination-pattern 1408555....

Define the destination telephone number associated with the POTS dial peer.

Step 5 

West (config-dial-peer)# port 0/0

Enter the port and slot number associated with this POTS dial peer.

Configure VoIP dial peers for outgoing calls and associate destination phone numbers on the East MRP with that MRP IP address, as shown in Figure 5-11, and in the following commands:

Command Purpose

Step 1 

West (config)# dial-peer voice 121 voip

Enter dial-peer configuration mode.

Step 2 

West (config-dial-peer)# destination-pattern 1919555....

Define the destination telephone number associated with the VoIP dial peer.

Step 3 

West (config-dial-peer# session target ipv4:192.168.11.3

Enter the port and slot number associated with this VoIP dial peer.

Step 4 

West (config-dial-peer)# exit

Return to configuration mode.


Figure 5-11: Linking PBXs over the IP Network (Remote Dial Peers)


Now configure number expansion so that numbers beginning with 5 (belonging to the East office) and sent by the West PBX to the West MRP are expanded into the full destination pattern:

West(config)# num-exp 5.... 1919555....

 

Note   You do not need to configure number expansion for calls from one West telephone to another West telephone because the PBX switches those calls.

Finally, enter the following global configuration voice-port command to configure the E&M port:

Command Purpose

Step 1 

West (config)# voice-port 0/0

Enter voice port configuration mode.

Step 2 

West (config-voice-port)# signal immediate

Select the signal type for this interface.

Step 3 

West (config-voice-port)# operation 4-wire

Select the appropriate cabling scheme for this voice port.

Step 4 

West (config-voice-port)# type 2

Select the appropriate E&M interface type.


Note   For these commands to take effect, you have to cycle the port by using the shutdown and no shutdown commands.


Note   Configure the PBX to pass all dual-tone multifrequency (DTMF) signals to the MRP.

Configure the East MRP similar to the West MRP. The East MRP connects to the PBX through an E&M VIC port 0/1. Enter the following commands to configure a POTS dial peer for all East telephones:

Command Purpose

Step 1 

East (config)# dial-peer voice 211 pots

Enter dial-peer configuration mode.

Step 2 

East (config-dial-peer)# destination-pattern 1919555....

Define the destination telephone number associated with the POTS dial peer.

Step 3 

East (config-dial-peer)# port 0/1

Enter the port/slot number associated with this POTS dial peer.

Enter the following commands to configure a VoIP dial peer for telephones on the West MRP:

Command Purpose

Step 1 

East (config)# dial-peer voice 221 voip

Enter dial-peer configuration mode.

Step 2 

East (config-dial-peer)# destination-pattern 1408555....

Define the destination telephone number associated with the POTS dial peer.

Step 3 

East (config-dial-peer)# session target ipv4:192.168.19.27

Enter the port/slot number associated with this POTS dial peer.

Step 4 

East (config-dial-peer)# exit

Return to configuration mode.

Enter the following commands to configure number expansion and to make it easy for East users to dial numbers on the West MRP:

West(config)# num-exp 5.... 1408555....

 

Finally, configure the E&M port:

Command Purpose

Step 1 

East (config)# voice-port 0/1

Enter voice port configuration mode.

Step 2 

East (config-voice-port)# signal immediate

Select the signal type for this interface.

Step 3 

East (config-voice-port)# operation 4-wire

Select the appropriate cabling scheme for this voice port.

Step 4 

East (config-voice-port)# type 2

Select the appropriate E&M interface type.

Verifying the Configuration

If you configured the E&M interfaces correctly, you can place calls from a telephone served by one PBX to a telephone served by the other PBX (using just the extension, if you configured number expansion). If you have trouble placing calls, ping the remote MRP to make sure you have IP connectivity.


Note   Refer to the section "Configuring Quality of Service" if you need to improve the quality of voice connections.


Note   To prevent the loss of MRP configuration, refer to the "Saving Configuration Changes" section in this chapter.

Configuring MFT-T1 CAS VWIC

Configure the multiflex T1 (MFT-T1) interface card (also referred to as T1) as a VIC (voice) in a channelized mode. Connecting the VWIC to a PBX or PSTN enables 24 channels or 24 simultaneous calls at any given time. VWIC has the flexibility to combine channels to form channel groups with the same characteristics.

Channel-associated signaling (CAS) is the transmission of signaling information within the voice channel. Various types of CAS signaling are available in the T1 world. The most common forms of CAS signaling are loop-start, ground-start, and E&M. The main disadvantage of CAS signaling is its use of user bandwidth to perform signaling functions. CAS signaling is often referred to as robbed-bit signaling because user bandwidth is being "robbed" by the network for other purposes. In addition to receiving and placing calls, CAS signaling processes the receipt of DNIS and ANI information, which is used to support authentication and other functions.

T1 CAS capabilities have been implemented on the Cisco ICS 7750 to enhance and integrate T1 CAS capabilities on common central office (CO) and PBX configurations for voice calls. The service provider application for T1 CAS includes connectivity to the public network using T1 CAS from the Cisco ICS 7750 to the end office switch.

T1 CAS Signaling Systems

VoIP for the Cisco ICS 7750 supports the following T1 CAS signaling systems:

Channelized T1 Robbed-Bit Features

Internet service providers can provide switched 56-kbps access to their customers using the Cisco ICS 7750. The subset of T1 CAS (robbed-bit) supported signaling commands are as follows:

Supervisory: line side

Supervisory: trunk side

TDM Clock

Digital T1 ports require not only that you set timing, but that you consider the source of the timers. You must configure the time division multiplexing (TDM) clock to specify the clock source. You can specify up to two external clock sources for each MRP, which means that only two of the T1 ports can use line as the clock source. The clock source is selected by using the tdm clock global configuration command.

Configurations Supported on a Single MRP

The MRP supports the following T1 port configurations:

  Even though the MRP can configure two T1 voice ports, it can only make 24 simultaneous calls.

Note   Define the port exporting the clock before importing a clock source from it.

Configuring TDM Clock

To configure the tdm clock, use the following commands beginning in privileged EXEC mode:

Command Purpose

Step 1 

MRP# configure terminal

Enter global configuration mode.

Step 2 

MRP(config)# tdm clock ?

Query the tdm clock commands by typing a question mark after the command.

Step 3 

MRP(config)# tdm clock T1 0/0

Specify the slot and port number of the T1 interface to configure. These numbers can be 0/0, 0/1, 1/0, or 1/1.

Step 4 

MRP(config)# tdm clock T1 0/0 {voice | data | both} ?

Select T1 interface payload type. The parameters represent as follows:
voice—T1 is used for only voice
data—T1 is used for only data
both—T1 is used for both voice and data

Query for more options by typing a question mark.

Step 5 

MRP(config)# tdm clock T1 0/0 both {export | import} ?

The parameters represent as follows:
export—TDM clock is provided by the line (PSTN or PBX) to which this port is connected and might export this clock to other T1 ports.
import—TDM clock is provided by the onboard clock or the line clock of one of the other exporting T1 ports.
Query for more options by typing a question mark.

Step 6 

MRP(config)# tdm clock T1 0/0 both export line

Specify that Network Interface (NI) provides clock to the line to which this port is connected.

Step 7 

MRP(config)# tdm clock T1 0/0 both import onboard

Specify that onboard clock provides the clock to the line to which this port is connected.

Step 8 

MRP(config)# tdm clock T1 0/0 both import T1 0/1 {internal | line}

Specify which end of the circuit provides the clock to the TDM switch. If internal is selected, the onboard clock provides the clocking. If line is selected, the other end of the circuit (PSTN) provides the clocking.

Step 9 

MRP(config)# tdm clock T1 0/0 both import T1 0/1 line

Specify the clocking that is provided from one T1 slot and port to the other T1 slot and port on the same MRP. If line is selected, the first T1 is the backup clock source for the second T1.

Step 10 

MRP(config)# tdm clock T1 0/0 both import T1 0/1 internal

If internal is selected, the onboard clock source is the only backup clock source for the first T1.

Step 11 

MRP(config)# tdm clock T1 0/0 both import onboard internal

Specify that the clocking to the T1 0/0 is provided by the onboard clock.

Clocking Inside the MRP

To understand the export and import options of the tdm clock command, it is necessary to understand the clocking inside the MRP. Use the export option on the port that drives the PLL (phase lock loop) inside the MRP. Use the import option on the port that is driven by the PLL.


Figure 5-12: Clocking inside the MRP


The following configuration sets up this clocking method:

MRP(config)# tdm clock T1 0/0 voice export line

MRP(config)# tdm clock T1 0/1 voice import T1 0/0 internal
 

Port 0/0 takes the clock source from the PSTN (line) and exports it to the PLL. Port 0/1 then takes the clock source from the PLL (internal) and imports it to the PBX.

Default TDM Clock

Default ports on the MRP have the following features:

Depending on the VICs inserted in the two ports, there are different default tdm clock values on power up. (See Table 5-17.)


Table 5-17: Default tdm clock values
VIC in Slot 0 VIC in Slot 1 Default tdm clock Values

2MFT-T1

2MFT-T1

tdm clock T1 0/0 both export line

tdm clock T1 0/1 voice import T1 0/0 line

(ports 1/0 and 1/1 are undefined)

Either empty or have an analog VIC

2MFT-T1

tdm clock T1 1/0 both export line

tdm clock T1 1/1 voice import T1 1/0 line

1MFT-T1

2MFT-T1

tdm clock T1 0/0 both export line

tdm clock T1 1/0 voice import T1 0/0 line

(port 1/1 is undefined)

Either empty or have a serial WIC

2MFT-T1

(No DSP PVDM present)

tdm clock T1 1/0 data export line

(port 1/1 undefined)

Enter the show tdm clock command to verify your configuration.

MRP# show tdm clock

Controller  Payload   State    tdm clock-type
0/0           Voice      up    Import 0/1 Line
0/1           Voice      up    Export Line
1/0            Data      up    Export Line
 
tdm clock   Sourced           Feed          Back-Up
0               0/1            0/0              0/0
Configuring T1 CAS for VoIP

To configure T1 CAS for VoIP on the MRP, use the following commands beginning in privileged EXEC mode:

Command Purpose

Step 1 

MRP# configure terminal

Enter global configuration mode.

Step 2 

MRP(config)# controller t1 number

Enter controller configuration mode to configure your controller port. Enter the controller ports as 0/0, 0/1, 1/0 or 1/1.

Step 3 

MRP(config-controller)# framing {sf | esf}

Enter the framing type designated by your telephone company.

Step 4 

MRP(config-controller)# linecode {ami | b8zs}

Enter the linecode type designated by your telephone company.

Step 5 

MRP(config-controller)# IREFOB
J:1099430ds0 group number 
timeslots range  type signal

Enter a number for the ds0 group. Enter 1-24 for range on the T1 port.

Configure all channels for E&M, FXS, and FXO analog signaling. Signaling types include e&m-immediate-start, e&m-delay-dial, e&m-wink-start, fxs-ground-start, fxs-loop-start, fxo-ground-start, and fxo-loop-start.

You must use the same type of signaling that your central office uses.

Repeat Steps 2 through 5 to configure the other three controllers.


Note   Super Frame AMI 64K timeslot is not reliable because T1 interface requires one's density.

TDM Clocking Scenarios

This section describes the timing scenarios that can occur when different combinations of WICs/VICs are used on the two slots of the MRP. All digital T1 interfaces are connected to a PBX, CO, or both. In all of the examples below, the PSTN (or Central Office) and the PBX can both provide and receive clocking.

The MRP has two on-board PLL (Phase-Lock Loop) chips that can derive clock source from any T1 interface on the system. The clock source is selected by using the tdm clock global configuration command. Both PLL can either provide a clock source to both T1 interfaces or receive clocking that can drive the second T1 interface.

The T1 interface payload type can be defined as either voice, data, or both. In the following scenarios, voice is the most commonly used payload type.

Configuration of TDM clocks affect the DSP groupings. (For information on DSP groups, refer to the "DSP Groups" section.) If only one clock source is used, the DSPs on both the PVDMs can be considered a single pool of DSP resource. If two clock sources are used, each PVDM constitutes a separate pool of DSP resource. If a port is used for an analog VIC, a single PVDM constitutes the DSP resource. Therefore, depending on whether one or two clock sources are defined, the bindings between the DSP resources and the set of ports that they can service can vary.

The MRP supports the following T1 configurations:

  Even though the MRP can configure two T1 voice ports, it can only make 24 simultaneous calls.

Note   These scenarios apply to both data and voice MFT-T1 VWICs.

T1 in Slot 0

Table 5-18 describes the timing scenarios that can occur when slot 0 is a T1 interface and slot 1 is empty.


Table 5-18: T1 in SLot 0
Topology Slot 0 Slot 1 PVDM 0 PVDM 1 Clocking slot 0/port 0 Clocking slot 0/port 1 Clocking slot 1/port 0 Clocking slot 1/port 1

Single T1 port 0/0 provides the clock

T1

None

PVDM-20

None

Import onboard

None

None

None

Single T1 port 0/0 receives the clock from the line

T1

None

PVDM-20

None

Export line

None

None

None

Dual T1 ports. Both ports 0/0 and 0/1 receives the clock from the line

T1

None

PVDM-20

None

Export line

Export line

None

None

Dual T1 ports. Both ports 0/0 and 0/1 receive the clock from the line and one is in the loop-timed

T1

None

PVDM-20

None

Export line

Import T1 port 0/0 line

None

None

Dual T1ports. Port 0/0 receives the clock and port 0/1 provides the clock to the line

T1

None

PVDM-20

None

Export line

Import T1 port 0/0 internal

None

None

Dual T1 ports. Both ports 0/0 and 0/1 provide the clock to the line

T1

None

PVDM-20

None

Import onboard internal

Import onboard internal

None

None

Each of the topologies described in Table 5-18 are illustrated below.

Single T1 Port Provides Clocking

In this scenario, the digital T1 port 0/0 is the clock source for the connected device. The PLL generates the clock internally and drives the clocking on the T1 line.


Figure 5-13: Single T1 Port Providing Clock


The following configuration sets up this clocking method:

MRP(config)# tdm clock T1 0/0 voice import onboard

 

Note   Generally this method is useful only when connecting to a PBX, key system or channel bank. A Cisco VoIP Gateway rarely provides clocking to the CO, because CO clocking provides a higher Stratum level.

Single T1 Port Receiving Clock from the Line

In this scenario, the digital T1 port 0/0 receives clocking from the connected device (CO). The PLL clocking is driven by the clock reference on the receive (Rx) side of the T1 connection.


Figure 5-14: Single T1 Receiving Clock from Line


The following configuration sets up this clocking method:

MRP(config)# tdm clock T1 0/0 voice export line

Dual T1 Ports, Both Receive Clocking from the Line

In this scenario, there are two reference clocks. Both T1 ports 0/0 and 0/1 receive clock from the CO.


Figure 5-15: Dual T1 Ports Receiving Line Clocking


The following configuration sets up this clocking method:

MRP(config)# tdm clock T1 0/0 voice export line

MRP(config)# tdm clock T1 0/1 voice export line
Dual T1 Ports, Both Receive Clocking from the Line, and One is in the Loop-Timed Mode

In this scenario, T1 port 0/0 receives clocking for the PLL from the CO and puts the T1 port 0/1 connected to the CO into looped-time mode. This is usually the best method because the CO provides an excellent clock source.


Figure 5-16: Dual T1 Ports Receiving Line Clocking


The following configuration sets up this clocking method:

MRP(config)# tdm clock T1 0/0 voice export line

MRP(config)# tdm clock T1 0/1 voice import t1 0/0 line

Dual T1 Ports, One Receives Clocking and One Provides Clocking

In this scenario, the digital T1 port 0/0 receives clocking for the PLL from the CO and uses this clock as a reference to clock T1 port 0/1. If T1 port 0/0 fails, the PLL internally generates the clock reference to drive T1 port 0/1.


Figure 5-17: Dual T1 Ports, One Receiving and One Providing Clocking


The following configuration sets up this clocking method:

MRP(config)# tdm clock T1 0/0 voice export line

MRP(config)# tdm clock T1 0/1 voice import t1 0/0 internal

Dual T1 Ports, Both Clocks from the MRP

In this scenario, the MRP generates the clock for the PLL and provides clocking to both T1 port 0/0 connected to a CO and T1 port 0/1 connected to a PBX.


Figure 5-18: Dual T1 Ports, Both Clocks from the MRP


The following configuration sets up this clocking method:

MRP(config)# tdm clock T1 0/0 voice import onboard internal

MRP(config)# tdm clock T1 0/1 voice import onboard internal

T1 in Both Slot 0 and Slot 1

Table 5-19 describes the timing scenarios that can occur when both slot 0 and slot 1 are T1 interfaces.


Table 5-19: T1 in Both SLot 0 and Slot 1
Topology Slot 0 Slot 1 PVDM 0 PVDM 1 Clocking slot 0/port 0 Clocking slot 0/port 1 Clocking slot 1/port 0 Clocking slot 1/port 1

Dual T1 ports. Both ports 0/0 and 0/1 receives the clock from two different line sources.

T1

T1

PVDM-20

PVDM-20

Export line

None

Export line

None

Dual T1 ports. Both ports 0/0 and 0/1 receive the clock from the line and one is in the loop-timed mode.

T1

T1

PVDM-20

PVDM-20

Export line

None

Import T1 port 0/0 line

None

Dual T1ports. Port 0/0 receives the clock and port 0/1 provides the clock to the line.

T1

T1

PVDM-20

PVDM-20

Export line

None

Import T1 port 0/0 internal

None

Dual T1 ports. Both ports 0/0 and 0/1 provide the clock to the line.

T1

T1

PVDM-20

PVDM-20

Import onboard

None

Import onboard

None

Each of the topologies described in Table 5-19 are illustrated below.

Dual T1 Ports, Both Receive Clocking from the Line

In this scenario, there are two reference clocks. Both T1 ports 0/0 and 1/0 receive clock from the CO.


Figure 5-19: Dual T1 Ports Receiving Line Clocking


The following configuration sets up this clocking method:

MRP(config)# tdm clock T1 0/0 voice export line

MRP(config)# tdm clock T1 1/0 voice export line
Dual T1 Ports, Both Receive Clocking from the Line, and One is in the Loop-Timed Mode

In this scenario, T1 port 0/0 receives clocking for the PLL from the CO and puts the T1 port 1/0 connected to the CO into looped-time mode. This is usually the best method because the CO provides an excellent clock source.


Figure 5-20: Dual T1 Ports Receiving Line Clocking


The following configuration sets up this clocking method:

MRP(config)# tdm clock T1 0/0 voice export line

MRP(config)# tdm clock T1 1/0 voice import t1 0/0 line

Dual T1 Ports, One Receives Clocking and One Provides Clocking

In this scenario, the digital T1 port 0/0 receives clocking for the PLL from the CO and uses this clock as a reference to clock T1 port 1/0. If T1 port 0/0 fails, the PLL internally generates the clock reference to drive T1 port 1/0.


Figure 5-21: Dual T1 Ports, One Receiving and One Providing Clocking


The following configuration sets up this clocking method:

MRP(config)# tdm clock T1 0/0 voice export line

MRP(config)# tdm clock T1 1/0 voice import t1 0/0 internal

Dual T1 Ports, Both Clocks from the MRP

In this scenario, the MRP generates the clock for the PLL and provides clocking to both T1 port 0/0 connected to a CO and T1 port 1/0 connected to a PBX.


Figure 5-22: Dual T1 Ports, Both Clocks from the MRP


The following configuration sets up this clocking method:

MRP(config)# tdm clock T1 0/0 voice import onboard 

MRP(config)# tdm clock T1 0/1 voice import onboard 

T1 in Slot 0 and an Analog VIC in Slot 1

Table 5-20 describes the timing scenarios that can occur when slot 0 is a T1 interface and slot 1 is an analog VIC interface.


Table 5-20: T1 in SLot 0 and an Analog VIC in Slot 1
Topology Slot 0 Slot 1 PVDM 0 PVDM 1 Clocking slot 0/port 0 Clocking slot 0/port 1 Clocking slot 1/port 0 Clocking slot 1/port 1

Dual T1 ports. Both ports 0/0 and 0/1 receive the clock from the line and one is in the loop-timed mode.

T1

VIC

PVDM-20

PVDM-4

Export line

Import T1 port 0/0 line

None

None

Dual T1ports. Port 0/0 receives the clock and port 0/1 provides the clock to the line.

T1

VIC

PVDM-20

PVDM-4

Export line

Import T1 port 0/0 internal

None

None

Dual T1 ports. Both ports 0/0 and 0/1 provide the clock to the line.

T1

VIC

PVDM-20

PVDM-4

Import onboard

Import onboard

None

None


Note   The MRP does not support the scenario in which both T1 ports in slot 0 are receiving clock from the line and there is a VIC installed in slot 1. The VIC utilizes one clock source and therefore the two T1 ports cannot receive two other clock sources because there is a limit of two clock sources in the MRP.

Each of the topologies described in Table 5-20 are illustrated below.

Dual T1 Ports, Both Receive Clocking from the Line

In this scenario, there are two reference clocks. Both T1 ports 0/0 and 0/1 receive clock from the CO.


Figure 5-23: Dual T1 Ports Receiving Line Clocking


The following configuration sets up this clocking method:

MRP(config)# tdm clock T1 0/0 voice export line

MRP(config)# tdm clock T1 0/1 voice export line
Dual T1 Ports, Both Receive Clocking from the Line, and One is in the Loop-Timed Mode

In this scenario, T1 port 0/0 receives clocking for the PLL from the CO and puts the T1 port 0/1 connected to the CO into looped-time mode. This is usually the best method because the CO provides an excellent clock source.


Figure 5-24: Dual T1 Ports Receiving Line Clocking


The following configuration sets up this clocking method:

MRP(config)# tdm clock T1 0/0 voice export line

MRP(config)# tdm clock T1 0/1 voice import t1 0/0 line

Dual T1 Ports, One Receives Clocking and One Provides Clocking

In this scenario, the digital T1 port 0/0 receives clocking for the PLL from the CO and uses this clock as a reference to clock T1 port 0/1. If T1 port 0/0 fails, the PLL internally generates the clock reference to drive T1 port 0/1.


Figure 5-25: Dual T1 Ports, One Receiving and One Providing Clocking


The following configuration sets up this clocking method:

MRP(config)# tdm clock T1 0/0 voice export line

MRP(config)# tdm clock T1 0/1 voice import t1 0/0 internal

Dual T1 Ports, Both Clocks from the MRP

In this scenario, the MRP generates the clock for the PLL and provides clocking to both T1 port 0/0 connected to a CO and T1 port 0/1 connected to a PBX.


Figure 5-26: Dual T1 Ports, Both Clocks from the MRP


The following configuration sets up this clocking method:

MRP(config)# tdm clock T1 0/0 voice import onboard internal

MRP(config)# tdm clock T1 0/1 voice import onboard internal

T1 in Slot 0 and an Analog WIC in Slot 1

Table 5-21 describes the timing scenarios that can occur when slot 0 is a T1 interface and slot 1 is an analog WIC interface.


Table 5-21: T1 in SLot 0 and an Analog WIC in Slot 1
Topology Slot 0 Slot 1 PVDM 0 PVDM 1 Clocking slot 0/port 0 Clocking slot 0/port 1 Clocking slot 1/port 0 Clocking slot 1/port 1

Dual T1 ports. Both ports 0/0 and 0/1 receives the clock from two different line sources.

T1

WIC

PVDM-20

None

Export line

Export line

None

None

Dual T1 ports. Both ports 0/0 and 0/1 receive the clock from the line and one is in the loop-timed mode.

T1

WIC

PVDM-20

None

Export line

Import T1 port 0/0 line

None

None

Dual T1ports. Port 0/0 receives the clock and port 0/1 provides the clock to the line.

T1

WIC

PVDM-20

None

Export line

Import T1 port 0/0 internal

None

None

Dual T1 ports. Both ports 0/0 and 0/1 provide the clock to the line.

T1

WIC

PVDM-20

None

Import onboard

Import onboard

None

None


Note   T1 data should not be configured on port 1 of either slot when a WIC is present on the same MRP because WIC takes the same data path as port 1 of the other slot.

Each of the topologies described in Table 5-21 are illustrated below.

Dual T1 Ports, Both Receive Clocking from the Line

In this scenario, there are two reference clocks. Both T1 ports 0/0 and 0/1 receive clock from the CO.


Figure 5-27: Dual T1 Ports Receiving Line Clocking


The following configuration sets up this clocking method:

MRP(config)# tdm clock T1 0/0 voice export line

MRP(config)# tdm clock T1 0/1 voice export line
Dual T1 Ports, Both Receive Clocking from the Line, and One is in the Loop-Timed Mode

In this scenario, T1 port 0/0 receives clocking for the PLL from the CO and puts the T1 port 0/1 connected to the CO into looped-time mode. This is usually the best method because the CO provides an excellent clock source.


Figure 5-28: Dual T1 Ports Receiving Line Clocking


The following configuration sets up this clocking method:

MRP(config)# tdm clock T1 0/0 voice export line

MRP(config)# tdm clock T1 0/1 voice import t1 0/0 line

Dual T1 Ports, One Receives Clocking and One Provides Clocking

In this scenario, the digital T1 port 0/0 receives clocking for the PLL from the CO and uses this clock as a reference to clock T1 port 0/1. If T1 port 0/0 fails, the PLL internally generates the clock reference to drive T1 port 0/1.


Figure 5-29: Dual T1 Ports, One Receiving and One Providing Clocking


The following configuration sets up this clocking method:

MRP(config)# tdm clock T1 0/0 voice export line

MRP(config)# tdm clock T1 0/1 voice import t1 0/0 internal

Dual T1 Ports, Both Clocks from the MRP

In this scenario, the MRP generates the clock for the PLL and provides clocking to both T1 port 0/0 connected to a CO and T1 port 0/1 connected to a PBX.


Figure 5-30: Dual T1 Ports, Both Clocks from the MRP


The following configuration sets up this clocking method:

MRP(config)# tdm clock T1 0/0 voice import onboard internal

MRP(config)# tdm clock T1 0/1 voice import onboard internal

Verifying T1 CAS Configuration

To verify that your controller is up and running and no alarms have been reported, enter the show controller t1 command and specify the port number.

    MRP# show controller t1 0/0
     T1 0/0 is up.
       No alarms detected.
       Version info of slot 0:  HW: 2, Firmware: 16, PLD Rev: 0
     
     Manufacture Cookie Info:
      EEPROM Type 0x0001, EEPROM Version 0x01, Board ID 0x42,
      Board Hardware Version 1.0, Item Number 73-2217-4,
      Board Revision A0, Serial Number 06467665,
      PLD/ISP Version 0.0, Manufacture Date 14-Nov-1997.
     
       Framing is ESF, Line Code is B8ZS, Clock Source is Internal.
       Data in current interval (269 seconds elapsed):
        0 Line Code Violations, 0 Path Code Violations
          0 Slip Secs, 0 Fr Loss Secs, 0 Line Err Secs, 0 Degraded Mins
          0 Errored Secs, 0 Bursty Err Secs, 0 Severely Err Secs, 0 Unavail Secs
    

Note the following:

For troubleshooting information on T1 controller command, refer to the Cisco ICS 7750 Administration and Troubleshooting Guide.


Note   To prevent the loss of MRP configuration, refer to the "Saving Configuration Changes" section in this chapter.

Configuring Dial Plans

Use a dial plan to map the destination telephone numbers with the voice ports on the MRP. In North America, the North American Numbering Plan (NANP) is used, which consists of an area code, an office code, and a station code. Area codes are assigned geographically, office codes are assigned to specific switches, and station codes identify a specific port on that switch. The format in North America is 1Nxx-Nxx-xxxx, with N = digits 2 through 9 and x = digits 0 through 9. Internationally, each country is assigned a one- to three-digit country code; the country's dialing plan follows the country code.

In most corporate environments, the telephone network is configured so that you can reach a destination by dialing only a portion (an extension number) of the full E.164 telephone number. VoIP can be configured to recognize extension numbers and expand them into their full E.164 dialed number by using two commands in tandem: destination-pattern and num-exp. Before you configure these two commands, it helps to map individual telephone extensions with their full E.164 dialed numbers. This can be done easily by creating a number expansion table.

For Cisco voice implementations, two types of dial peers are used to match a dialed number to either a local telephony port or a remote IP address:

    West(config)# dial-peer voice 401 pots
    West(config-dial-peer)# destination-pattern 14085553737
    West(config-dial-peer)# port 0/0
    
  The destination-pattern command defines the telephone number associated with the POTS dial peer. The port command associates the POTS dial peer with a specific logical dial interface, normally the voice port connecting your MRP to the local POTS network.
    West(config)# dial-peer voice 501 voip
    West(config-dial-peer)# destination-pattern 1919555....
    West(config-dial-peer)# session target ipv4:192.168.11.3
    
  The destination-pattern command defines the telephone number associated with the VoIP dial peer. The session target command specifies a destination IP address for the VoIP dial peer.

Use the dial-peer voice command to define dial peers and change to dial-peer configuration mode. To see an example, refer to the individual sections on configuring FXS, FXO, and E&M interfaces earlier in this chapter.

Create a Number Expansion Table

In Figure 5-31, a small company decides to use VoIP to integrate its telephony network with its existing IP network. The destination pattern (or expanded telephone number) associated with MRP 1 (left of the IP cloud) is (408) 555-xxxx, where xxxx identifies the individual dial peers by extension. The destination pattern (or expanded telephone number) associated with MRP 2 (right of the IP cloud) is (729) 555-xxxx.


Figure 5-31: Sample VoIP Network


Table 5-22 shows the number expansion table for this scenario.


Table 5-22: Sample Number Expansion Table
Extension Destination Pattern Num-Exp Command Entry Description

1...

14085551...

num-exp 1... 14085551...

To expand a 4-digit extension beginning with the numeral 1 by prefixing 1408555 to it.

2...

14085552...

num-exp 2... 14085552...

To expand a 4-digit extension beginning with the numeral 2 by prefixing 1408555 to it.

3...

17295553...

num-exp 3... 17295553...

To expand a 4-digit extension beginning with the numeral 3 by prefixing 1729555 to it.

4...

17295554...

num-exp 4... 17295554...

To expand a 4-digit extension beginning with the numeral 4 by prefixing 1729555 to it.


Note   You can use a period (.) to represent variables (such as extension numbers) in a telephone number. A period is similar to a wildcard, which matches any entered digit.

The information included in this example needs to be configured on both MRP 1 and MRP 2. In this configuration, MRP 1 can call any number string that begins with the digits 17295553 or 17295554 to connect to MRP 2. Similarly, MRP 2 can call any number string that begins with the digits 14085551 and 14085552 to connect to MRP 1.

Configuring Number Expansion

To define how to expand an extension number into a particular destination pattern, use the following global configuration command:

East(config)# num-exp extension-number extension-string
 

Use the show num-exp command to verify that you have mapped the telephone numbers correctly.

East# show num-exp dialed-number

After you have configured dial peers and assigned destination patterns to them, use the show dialplan number command to see how a telephone number maps to a dial peer.

East# show dialplan number dialed-number

Note   You must still configure each telephone number in full on a local dial peer so that the MRP can find the voice port it belongs to.

Configuring VoIP for Frame Relay

You need to take certain factors into consideration when configuring VoIP so that it runs smoothly over Frame Relay. A public Frame Relay cloud provides no guarantees for QoS. For real-time traffic to be transmitted in a timely manner, the data rate must not exceed the committed information rate (CIR), or packets might be dropped. In addition, Frame Relay traffic shaping and RSVP are mutually exclusive. This is particularly important to remember if multiple data-link connection identifiers (DLCIs) are carried on a single interface.

For Frame Relay links with slow output rates (less than or equal to 64 kbps), where data and voice are being transmitted over the same permanent virtual circuit (PVC), we recommend the following solutions:


Note   Lowering the MTU size affects data throughput speed.

In IOS Release 12.0, Frame Relay traffic shaping is not compatible with RSVP. We suggest one of the following workarounds:

Frame Relay for VoIP Configuration Example

For Frame Relay, it is customary to configure a main interface and several subinterfaces with one subinterface per PVC. The following example configures a Frame Relay main interface and a subinterface so that voice and data traffic can be successfully transported:

interface Serial 0/0
 mtu 300
 no ip address
 encapsulation frame-relay
 no ip route-cache
 no ip mroute-cache
 fair-queue 64 256 1000
 frame-relay ip rtp header-compression
 
interface Serial 0/0.1 point-to-point
 mtu 300
 ip address 40.0.0.7 255.0.0.0
 ip rsvp bandwidth 48 48
 no ip route-cache
 no ip mroute-cache
 bandwidth 64
 traffic-shape rate 32000 4000 4000
 frame-relay interface-dlci 16
 frame-relay ip rtp header-compression
 

In this configuration example, the main interface is configured as follows:

The subinterface is configured as follows:


Note   When traffic bursts over the CIR, the output rate is held at the speed configured for the CIR (for example, traffic will not go beyond 32 kbps if CIR is set to 32 kbps).

For more information about configuring Frame Relay for VoIP, refer to the "Configuring Frame Relay" chapter in the Wide-Area Networking Configuration Guide for IOS Release 12.0.

To prevent the loss of MRP configuration, refer to the "Saving Configuration Changes" section in this chapter.

Configuring Quality of Service

You need to have a well-engineered, end-to-end network when running delay-sensitive applications such as VoIP. Voice traffic is much more sensitive to timing variations than data traffic. For good voice performance, you need to configure your data network so that voice packets are not lost or delayed. Fine-tuning your network to adequately support VoIP involves a series of protocols and features to improve quality of service (QoS). It is beyond the scope of this document to explain the specific details relating to wide-scale QoS deployment. Cisco IOS software provides many tools for enabling QoS on your backbone, such as Random Early Detection (RED), Weighted Random Early Detection (WRED), Fancy Queuing (meaning custom, priority, or weighted fair queuing), and IP precedence. To configure your IP network for real-time voice traffic, you must take into consideration the entire scope of your network and then select the appropriate QoS tool or tools.


Note   QoS measures the level of network performance. It does not directly measure the quality of the voice signal.

The important thing to remember is that QoS must be configured throughout your network—not just on your MRP running VoIP—to improve voice network performance.

Need for Quality of Service

On a relatively low-bandwidth connection, such as a PPP or High-Level Data Link Control (HDLC) serial link, you should consider using methods to ensure QoS. If you have a high-bandwidth network, such as Ethernet or Fast Ethernet, and voice and data traffic together occupy only a small fraction of the bandwidth available, you might not need to provide QoS. (See Figure 5-32.)


Figure 5-32: Bandwidth versus Quality of Service


Although not mandatory, some QoS tools can be valuable in fine-tuning your network to support real-time voice traffic. To configure your IP network for QoS, perform one or more of the tasks in the following sections:

Configuring Custom Queuing

Some QoS features, such as IP RTP reserve and custom queuing, are based on the transport protocol and the associated port number. Real-time voice traffic is carried on UDP ports ranging from 16384 to 16624. This number is derived from the following formula:

16384 + (4 x number of voice ports in the MRP)
 

Custom Queuing and other methods for identifying high priority streams should be configured for these port ranges. For more information about custom queuing, refer to the "Managing System Performance" chapter in the Configuration Fundamentals Configuration Guide for IOS Release 12.0.

Configuring Weighted Fair Queuing

Weighted fair queuing ensures that queues do not starve for bandwidth and that traffic gets predictable service. Low-volume traffic streams receive preferential service; high-volume traffic streams share the remaining capacity, obtaining equal or proportional bandwidth.

In general, weighted fair queuing is used in conjunction with multilink PPP with interleaving and RSVP or IP precedence to ensure voice packet delivery. Use weighted fair queuing with multilink PPP to define how data is managed; use RSVP or IP precedence to give priority to voice packets. For more information about weighted fair queuing, refer to the "Managing System Performance" chapter in the Configuration Fundamentals Configuration Guide for IOS Release 12.0.

Configuring IP Precedence

Use the ip precedence command to give voice packets a higher priority over other IP data traffic. Every IP packet is given a precedence level. In IP precedence, the numbers 1 through 5 identify classes for IP flows; the numbers 6 through 7 are used for network and backbone routing and updates. You can configure voice packets for higher priority by setting the IP precedence value to 5. Internal MRPs using weighted fair queuing give these packets priority. This command applies only to VoIP dial peers. The following example sets the IP precedence to 5:

MRP> enable

Password:
MRP# configure terminal

MRP(config)# dial-peer voice 221 voip

MRP(config-dial-peer)# ip precedence 5

 

The ip precedence command should also be used if RSVP is not enabled and you want to give voice packets a higher priority over other IP data traffic.

Configuring RSVP for Voice

Resource Reservation Protocol (RSVP) enables MRPs to reserve enough bandwidth on an interface for reliability and quality performance. RSVP allows end systems to request a particular QoS from the network. Real-time voice traffic requires network consistency. Without consistent QoS, real-time traffic can experience jitter, insufficient bandwidth, delay variations, or information loss. RSVP works in conjunction with current queuing mechanisms. It is up to the interface queuing mechanism (such as weighted fair queuing or WRED) to implement the reservation.

RSVP works well on PPP, HDLC, and similar serial line interfaces. It does not work well on multi-access LANs. RSVP can be equated to a dynamic access list for packet flows.

You should configure RSVP to ensure QoS if the following conditions describe your network:

Enable RSVP

To minimally configure RSVP for voice traffic, you must enable RSVP on each interface where priority must be set.

By default, RSVP is disabled so that it is backwards compatible with systems that do not implement RSVP. To enable RSVP for IP on an interface, use the following interface configuration command:

MRP(config-if)# ip rsvp bandwidth [interface-kbps] [single-flow-kbps]

This command starts RSVP and sets the bandwidth and single-flow limits. The default maximum bandwidth is up to 75 percent of the bandwidth available on the interface. By default, the amount reservable by a flow can be up to the entire reservable bandwidth.

On subinterfaces, RSVP applies to the more restrictive of the available bandwidths of the physical interface and the subinterface.

Reservations on individual circuits that do not exceed the single flow limit normally succeed. However, if reservations are made on other circuits adding up to the line speed, and a reservation is made on a subinterface that has enough remaining bandwidth, reservation will still be refused because the physical interface lacks supporting bandwidth.

A MRP running VoIP and configured for RSVP requests allocations using the following formula:

bps=packet_size+ip/udp/rtp header size * 50 per second
 

For G.729, the allocation works out to be 24,000 bps. For G.711, the allocation is 80,000 bps.

For more information about configuring RSVP, refer to the "Configuring RSVP" chapter of the Network Protocols Configuration Guide, Part 1 for Cisco IOS Release 12.0.

RSVP Configuration Example

The following example enables RSVP and sets the maximum bandwidth to 100 kbps and the maximum bandwidth per single request to 32 kbps (the example assumes that both VoIP dial peers are configured):

MRP(config)# interface serial 0

MRP(config-if)# ip rsvp bandwidth 100 32

MRP(config-if)# fair-queue

MRP(config-if)# end

 

After enabling RSVP, you must also use the req-qos dial-peer configuration command to request an RSVP session on each VoIP dial peer. Otherwise, no bandwidth is reserved for voice traffic.

MRP(config)# dial-peer voice 211 voip

MRP(config-dial-peer)# req-qos controlled-load

 
MRP(config)# dial-peer voice 212 voip

MRP(config-dial-peer)# req-qos controlled-load

Configuring Multilink PPP with Interleaving

Multiclass multilink PPP interleaving allows large packets to be multilink-encapsulated and fragmented into smaller packets to satisfy the delay requirements of real-time voice traffic; small real-time packets, which are not multilink-encapsulated, are transmitted between fragments of the large packets. The interleaving feature also provides a special transmit queue for the smaller, delay-sensitive packets, enabling them to be transmitted earlier than other flows. Interleaving provides the delay bounds for delay-sensitive voice packets on a slow link that is used for other best-effort traffic.

In general, multilink PPP with interleaving is used in conjunction with weighted fair queuing and RSVP or IP precedence to ensure voice packet delivery. Use multilink PPP with interleaving and weighted fair queuing to define how data is managed; use RSVP or IP precedence to give priority to voice packets.

You should configure multilink PPP if the following conditions describe your network:


Note   Do not use multilink PPP on links greater than 2 Mbps.

Multilink PPP support for interleaving can be configured on virtual templates, dialer interfaces, and ISDN BRI or PRI interfaces. To configure interleaving, you need to complete the following tasks:

To configure multilink PPP and interleaving on a configured and operational interface or virtual interface template, use the following interface configuration commands:

Command Purpose

Step 1 

ppp multilink

Enable Multilink PPP.

Step 2 

ppp multilink interleave

Enable real-time packet interleaving.

Step 3 

ppp multilink fragment-delay milliseconds

Optionally, configure a maximum fragment delay of 20 milliseconds.

Step 4 

ip rtp reserve lowest-UDP-port range-of-ports [maximum-bandwidth]

Reserve a special queue for real-time packet flows to specified destination UDP ports, allowing real-time traffic to have higher priority than other flows. This only applies if you have not configured RSVP.


Note   You can use the ip rtp reserve command instead of configuring RSVP. If you configure RSVP, this command is not required.

For more information about multilink PPP, refer to the "Configuring Media-Independent PPP and Multilink PPP" chapter in the Dial Solutions Configuration Guide for Cisco IOS Release 12.0.

Multilink PPP Configuration Example

The following example defines a virtual interface template that enables multilink PPP with interleaving and a maximum real-time traffic delay of 20 milliseconds and then applies that virtual template to the multilink PPP bundle:

MRP(config)# interface virtual-template 1

MRP(config-if)# ppp multilink

MRP(config-if)# encapsulated ppp

MRP(config-if)# ppp multilink interleave

MRP(config-if)# ppp multilink fragment-delay 20

MRP(config-if)# ip rtp reserve 16384 100 64

 
MRP(config)# multilink virtual-template 1

Configuring RTP Header Compression

Real-Time Transport Protocol (RTP) is used for carrying audio traffic in packets over an IP network. RTP header compression compresses the IP/UDP/RTP header in an RTP data packet from 40 bytes to approximately 2 to 4 bytes (most of the time), as shown in Figure 5-33.

This compression feature is beneficial if you are running VoIP over slow links. Enabling compression on both ends of a low-bandwidth serial link can greatly reduce the network overhead if there is a lot of RTP traffic on that slow link.

Typically, an RTP packet has a payload of approximately 20 to 160 bytes for audio applications that use compressed payloads. RTP header compression is especially beneficial when the RTP payload size is small (for example, compressed audio payloads between 20 and 50 bytes).


Figure 5-33: RTP Header Compression


You should configure RTP header compression if the following conditions describe your network:


Note   Do not use RTP header compression on links greater than 2 Mbps.

Perform the following tasks to configure RTP header compression for VoIP. The first task is required; the second task is optional.

Enable RTP Header Compression on a Serial Interface

You need to enable compression on both ends of a serial connection. To enable RTP header compression, use the following interface configuration command:

MRP(config-if)# ip rtp header-compression [passive] 

 

If you include the passive keyword, the software compresses outgoing RTP packets only if incoming RTP packets on the same interface are compressed. If you use the command without the passive keyword, the software compresses all RTP traffic.

Change the Number of Header Compression Connections

By default, the software supports a total of 16 RTP header compression connections on an interface. To specify a different number of RTP header compression connections, use the following interface configuration command:

MRP(config-if)# ip rtp compression connections number
RTP Header Compression Configuration Example

The following example enables RTP header compression for a serial interface:

MRP(config)# interface serial0

MRP(config-if)# ip rtp header-compression

MRP(config-if)# encapsulation ppp

MRP(config-if)# ip rtp compression-connections 25

 

For more information about RTP header compression, see the "Configuring IP Multicast Routing" chapter of the Network Protocols Configuration Guide, Part 1 for Cisco IOS Release 12.0.


Note   When you enter the show running-config command, the format of the ip rtp header-compression command will change to ip rtp header-compression iphc-format.

Verifying the Interface Configuration

After configuring the new interface, you can perform the following tests to verify that the new interface is operating correctly:

    MRP_Slot1#show version
    Cisco Internetwork Operating System Software 
    IOS (tm) C1700 Software (C1700-SV3Y-M), Experimental Version 12.0(20000119:032355) [jlu-jlu-test_0118 100]
    Copyright (c) 1986-2000 by cisco Systems, Inc.
    Compiled Tue 18-Jan-00 19:23 by jlu
    Image text-base:0x80008088, data-base:0x807C2C10
     
    ROM:System Bootstrap, Version 12.0(3)T, RELEASE SOFTWARE (fc1)
     
    MRP_Slot1 uptime is 1 day, 1 hour, 50 minutes
    System returned to ROM by reload
    Running default software
     
    cisco 1750T (MPC860) processor (revision 0x00) with 36864K/12288K bytes of memory.
    Processor board ID 0000 (1314672220), with hardware revision 0000
    M860 processor:part number 0, mask 32
    Bridging software.
    X.25 software, Version 3.0.0.
    Primary Rate ISDN software, Version 1.1.
    1 FastEthernet/IEEE 802.3 interface(s)
    1 Serial(sync/async) network interface(s)
    2 Channelized T1/PRI port(s)
    32K bytes of non-volatile configuration memory.
     
    Configuration register is 0x0
    

    MRP_Slot1#show controller t1 0/0
    T1 0/0 is up.
      Applique type is Channelized T1
      Cablelength is long gain36 0db
      No alarms detected.
      Version info Firmware:19990616, FPGA:6
      Framing is ESF, Line Code is B8ZS, Clock Source is Line.
      Data in current interval (21 seconds elapsed):
         0 Line Code Violations, 0 Path Code Violations
         0 Slip Secs, 0 Fr Loss Secs, 0 Line Err Secs, 0 Degraded Mins
         0 Errored Secs, 0 Bursty Err Secs, 0 Severely Err Secs, 0 Unavail Secs
    

    MRP_Slot1#show protocols        
    Global values:
      Internet Protocol routing is enabled
    FastEthernet0 is up, line protocol is up
      Internet address is 1.16.164.201/16
    Serial0 is down, line protocol is down
      Internet address is 199.1.1.1/24
    
    MRP_Slot1#show interfaces       
    FastEthernet0 is up, line protocol is up 
      Hardware is PQUICC_FEC, address is 0050.73ff.727f (bia 0050.73ff.727f)
      Internet address is 1.16.164.201/16
      MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec, 
         reliability 255/255, txload 1/255, rxload 1/255
      Encapsulation ARPA, loopback not set
      Keepalive set (10 sec)
      Full-duplex, 100Mb/s, 100BaseTX/FX
      ARP type:ARPA, ARP Timeout 04:00:00
      Last input 00:00:00, output 00:00:09, output hang never
      Last clearing of "show interface" counters 00:00:07
      Queueing strategy:fifo
      Output queue 0/40, 0 drops; input queue 0/75, 0 drops
      5 minute input rate 4000 bits/sec, 4 packets/sec
      5 minute output rate 0 bits/sec, 0 packets/sec
         42 packets input, 5003 bytes
         Received 42 broadcasts, 0 runts, 0 giants, 0 throttles
         0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
         0 watchdog, 0 multicast
         0 input packets with dribble condition detected
         0 packets output, 0 bytes, 0 underruns
         0 output errors, 0 collisions, 0 interface resets
         0 babbles, 0 late collision, 0 deferred
         0 lost carrier, 0 no carrier
         0 output buffer failures, 0 output buffers swapped out
    Serial0 is down, line protocol is down 
      Hardware is PowerQUICC Serial
      Internet address is 199.1.1.1/24
      MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec, 
         reliability 255/255, txload 1/255, rxload 1/255
      Encapsulation FRAME-RELAY, loopback not set
      Keepalive not set
      FR SVC disabled, LAPF state down
      Broadcast queue 0/64, broadcasts sent/dropped 0/0, interface broadcasts 0
      Last input 05:34:50, output 05:34:57, output hang never
      Last clearing of "show interface" counters 00:00:09
      Input queue:0/75/0 (size/max/drops); Total output drops:0
      Queueing strategy:weighted fair
      Output queue:0/1000/64/0 (size/max total/threshold/drops) 
         Conversations  0/1/256 (active/max active/max total)
         Reserved Conversations 0/0 (allocated/max allocated)
      5 minute input rate 0 bits/sec, 0 packets/sec
      5 minute output rate 0 bits/sec, 0 packets/sec
         0 packets input, 0 bytes, 0 no buffer
         Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
         0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
         0 packets output, 0 bytes, 0 underruns
         0 output errors, 0 collisions, 0 interface resets
         0 output buffer failures, 0 output buffers swapped out
         0 carrier transitions
         DCD=up  DSR=up  DTR=down  RTS=down  CTS=up
    
    MRP_Slot1#show running-config
    Building configuration...
     
    Current configuration:
    !
    version 12.0
    service timestamps debug uptime
    service timestamps log uptime
    no service password-encryption
    !
    hostname MRP_Slot1
    !
    no logging console
    !
    !
    memory-size iomem 25
    tdm clock T1 0/0 voice export line
    tdm clock T1 0/1 voice import T1 0/0 internal
    ip subnet-zero
    no ip domain-lookup
    !
    !
    !controller T1 0/0
     ds0-group 0 timeslots 1-24 type e&m-wink-start
    !
    controller T1 0/1
     ds0-group 1 timeslots 1-24 type e&m-wink-start
    !
    !
    voice-port 0/0:0
    !
    voice-port 0/1:1
    !
    dial-peer voice 102 voip
     destination-pattern 250071100.
     codec g711ulaw
     session target ipv4:199.1.1.2
    !
    dial-peer voice 1021 voip
     destination-pattern 250072900.
     session target ipv4:1.16.164.105
    !
    dial-peer voice 200 pots
    destination-pattern 140071100.
    port 0/0:0
    prefix 140071100
    !
    process-max-time 200
    !
    interface FastEthernet0/0
     ip address 1.9.28.201 255.255.0.0
     speed auto
    !
    interface Serial1/0
     bandwidth 1544
     ip address 199.1.1.1 255.255.255.0
     encapsulation ppp
     no keepalive
     clockrate 4000000
     ip rsvp bandwidth
     
    ip classless
    no ip http server
    !
    snmp-server engineID local 000000090200005073FF727F
    snmp-server community xena RO
    snmp-server community hercules RW
    !
    line con 0
     exec-timeout 0 0
     transport input none
    line aux 0
    line vty 0 4
     login
    !
    !
    no scheduler allocate
    end
    

If an interface is down and you configured it as up, or if the displays indicate that the hardware is not functioning properly, make sure that the new interface is properly connected and configured.

Where to Go Next

At this point you can proceed to the following:


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Posted: Mon Oct 2 14:00:39 PDT 2000
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