AIS AI2524 Specify FT1/T1 Line-Code Type, Enable Remote Alarms, Service-module t1 lbo none

Chapter 14: T1 Interface Configuration Steps

To transmit packets without decreasing outgoing signal strength, typ this in interface configuration mode:

service-module t1 lbo none

The ideal signal strength should be between -15 dB and -22 dB, which is calculated by adding the phone company loss, cable length loss, and 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, type this in interface configuration mode:

service-module t1 linecode {ami b8zs}

Choose alternate mark inversion (AMI) or binary 8 zero substitution (B8ZS).

Configuring B8ZS is a method of ensuring the T1s density require ment 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 T1s density requirement in your router configuration using the service-mod- ule t1 data-coding inverted command or the service- module t1 timeslots speed 56 command.

In most cases, your T1 service provider determines which line-cod type, either ami or b8zs, is required for your T1 circuit.

Enable Remote Alarms

To generate remote alarms (yellow alarms) at the local CSU/DSU or detect remote alarms sent from the remote CSU/DSU, type this in in- terface configuration mode:

service-module t1 remote-alarm-enable

Remote alarms are transmitted by the CSU/DSU when it detects an alarm condition, such as a red alarm (loss of signal) or blue alarm (un- framed 1's). The receivingCSU/DSU then knows there is an error con- dition on the line.

With D4 super frame configured, a remote alarm condition is transmit- ted by setting the bit2 of each time slot to zero. For received user data that has the bit 2 of each time slot set to zero, the CSU/DSU will inter- pret the data as a remote alarm and interrupt data transmission, which explains why remote alarms are disabled by default. With Extended

August 1997	Page 14-3
2524UM