CISCO IOS in a Nutshell

Name

service-module t1 — interface

Synopsis

service-module t1 parameters
no service-module t1 parameters
            

Configures

Internal T1 CSU/DSU

Default

Depends on the command

Description

The service-module commands are for routers that have T1 CSU/DSU modules built into them. These commands set various options on the internal CSU/DSU. The parameters that can be configured are:

clock source {internal | line}

By default, the clock source for a T1 CSU/DSU is the line, which is provided by the carrier. This command allows you to switch to the internal clock source on the module.

data-coding {inverted | normal}

By default, the data coding is set to normal. Setting the data coding to inverted instructs the module to convert all 1s to 0s and all 0s to 1s. If the data coding is inverted on one end of the line, the other end must also be inverted or the connection will fail.

framing {esf | sf}

This command sets the framing type for the T1 module, which can be esf (Extended Superframe) or sf (Superframe). The default framing type for a T1 module is ESF.

lbo {-15 db | -7.5 db | none}

This command sets the line build-out value. -15 db decreases the outgoing signal by 15 decibels; -7.5 db decreases it by 7.5 decibels. Your provider will know what the build-out should be for your link. The default is no build-out (none) on the outgoing signal.

linecode {ami | b8zs}

By default, the line encoding is set to b8zs. It can be changed to ami with this command. Your service carrier provides the T1 linecode ...