Specifications

Configure Serial Interfaces for CSU/DSU Service Modules

IC-106

Cisco IOS Interface Configuration Guide

Enable Remote Alarms

To generate remote alarms (yellow alarms) at the local CSU/DSU or detect remote alarms sent from

the remote CSU/DSU, use the following command in interface conﬁguration mode:

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 (unframed 1’s). The receiving CSU/DSU then knows there is an

error condition on the line.

With D4 super frame conﬁgured, a remote alarm condition is transmitted by setting the bit 2 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

interprets the data as a remote alarm and interrupts data transmission, which explains why remote

alarms are disabled by default. With Extended Super Frame conﬁgured, the remote alarm condition

is signalled out of band in the facility data link.

You can see if the FT1/T1 CSU/DSU is receiving a remote alarm (yellow alarm) by issuing the show

service-module command.

To disable remote alarms, use the following command in interface conﬁguration mode:

Enable Loopcodes that Initiate Remote Loopbacks

To specify if the fractional T1/T1 CSU/DSU module goes into loopback when it receives a loopback

code on the line, use the following commands in interface conﬁguration mode:

Note By using the service-module t1 remote-loopback command without specifying any

keywords, you enable the standard-loopup codes, which use a 1-in-5 pattern for loopup and a 1-in-3

pattern for loopdown.

You can simultaneously conﬁgure the full and payload loopback points. However, only one

loopback payload code can be conﬁgured at a time. For example, if you conﬁgure the

service-module t1 remote-loopback payload alternate command, a payload v.54 request, which

is the industry standard and default, cannot be transmitted or accepted. Full and payload loopbacks

with standard-loopup codes are enabled by default.

Command Purpose

service-module t1 remote-alarm-enable Enable remote alarms.

Command Purpose

no service-module t1 remote-alarm-enable Disable remote alarms.

Step Command Purpose

1 service-module t1 remote-loopback

full

Conﬁgures the remote loopback code used to

transmit or accept CSU loopback requests.

2 service-module t1 remote-loopback

payload [alternate | v54

]

Conﬁgures the loopback code used by the local

CSU/DSU to generate or detect

payload-loopback commands.