Specifications

Specify the Frame Type of a FT/T1 Line
Configuring Serial Interfaces IC-105
Specify the Frame Type of a FT/T1 Line
To specify the frame type for a line using the FT1/T1 CSU/DSU module, use the following command
in interface configuration mode:
In most cases, the service provider determines which framing type, either esf or sf, is required for
your circuit.
Specify the CSU Line Build Out
To decrease the outgoing signal strength to an optimum value for the telecommunication carrier
network, use the following command on the FT1/T1 CSU/DSU module in interface configuration
mode:
To transmit packets without decreasing outgoing signal strength, use the following command in
interface configuration mode:
The ideal signal strength should be between –15 dB and –22 dB, which is calculated by adding the
phone company loss + cable length loss + line build out.
You may use this command in back-to-back configurations, but it is not needed on most actual T1
lines.
Specify FT1/T1 Line-Code Type
To configure the line code for the FT1/T1 CSU/DSU module, use the following command in
interface configuration mode:
Configuring B8ZS is a method of ensuring the ones density requirement on a T1 line by substituting
intentional bipolar violations in bit positions four and seven for a sequence of eight zero bits. When
the CSU/DSU is configured for AMI, you must guarantee the ones density requirement in your
router configuration using the service-module t1 data-coding inverted command or the
service-module t1 timeslots speed 56 command.
In most cases, your T1 service provider determines which line-code type, either ami or b8zs, is
required for your T1 circuit.
Command Purpose
service-module t1 framing {sf | esf} Specify a FT1/T1 frame type. Choose either D4 Super
Frame (sf) or Extended Super Frame (esf).
Command Purpose
service-module t1 lbo {-15 db | -7.5 db} Decrease the outgoing signal strength in decibels.
Command Purpose
service-module t1 lbo none
Transmits packets without decreasing outgoing
signal strength.
Command Purpose
service-module t1 linecode {ami | b8zs} Specify a line-code type. Choose alternate mark
inversion (AMI) or binary 8 zero substitution (B8ZS).