20-5
Cisco ASR 901 Series Aggregation Services Router Software Configuration Guide
OL-23826-09
Chapter 20 Configuring T1/E1 Controllers
Troubleshooting Controllers

Troubleshooting Controllers

This line card supports local and network T1/E1 loopback modes, and remote T1 loopback modes for
testing, network fault isolation, and agency compliance. You can test T1/E1 lines in local and network
loopback modes. You can also test T1 lines in remote mode.
Note The ASR901 supports activating or deactivating payload and line loopback modes using FDL in ESF
framing mode as defined in the T1.403 ANSI standard. The implementation confirms to ANSI
T1.403-1999, sections 9.4.2.1 and 9.4.2.2. The ASR901 only accepts remotely initiated loopback
requests and does not support initiation of FDL remote loopback requests.
Note Bit-error-rate testing and loopbacks are used to resolve problems and test the quality of T1/E1 links.

Troubleshooting E1 Controllers

To troubleshoot the E1 line card, complete the following steps in the controller configuration mode:
Step 7 Router(config-controller)#
cablelength {long [-15db | -22.5db
| -7.5db | 0db] short [110ft |
220ft | 330ft| 440ft | 550ft |
600ft]}
Configures the cable length.
Step 8 Router(config-controller)# exit Exits controller configuration mode.
Step 9 Router(config)# interface serial
slot/port
:channel
Configures the serial interface. Specify the T1 slot (always 0), port
number, and channel-group.
Step 10 Router(config-if)# encapsulation
ppp
Enters the following command to configure PPP encapsulation.
Step 11 Router(config-if)# keepalive
[
period
[
retries
]]
Enables keepalive packets on the interface and specify the number of
times that keepalive packets will be sent without a response the interface
is brought down:
Step 12 exit
Example:
Router(config)# exit
Router#
Exits configuration mode.
Command Purpose