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Diagnose a Suspected Circuit Problem
Purpose
When you suspect a circuit problem, it is important to work with the transport-layer engineer to resolve the problem. The transport-layer engineer may ask you to create a loop from the router to the network, or the engineer may create a loop to the router from various points in the network.
To diagnose a suspected circuit problem, follow these steps:
- Create a Loop from the Router to the Network
- Create a Loop to the Router from Various Points in the Network
Create a Loop from the Router to the Network
Purpose
Creating a loop from a particular T1 interface to the network allows the transport-layer engineer to test the T1 interface from various points in the network and isolate the problem.
Action
To create a loop from a particular T1 interface to the network, follow these steps:
- In configuration mode, go to the following hierarchy level:[edit]user@host# edit interfaces t1-fpc/pic/port:channel t1-options
- Configure the loopback:[edit interfaces interface-name t1-options]user@host# set loopback remote
- Verify the configuration:user@host# show
For example:
[edit interfaces t1-2/1/1:0:0 t1-options]user@host# show loopback remote; - Commit the configuration:user@host# commit
Meaning
This command loops any traffic from the network back into the network.
Create a Loop to the Router from Various Points in the Network
Purpose
The transport-layer engineer creates a loop to the router from various points in the network. You can then perform tests to verify the connection from the router to that loopback in the network.
Action
After the transport-layer engineer has created the loop to the router from the network, you must verify the connection from the router to the loopback in the network. Follow Steps 2 through 7 in Diagnose a Suspected Hardware Problem with a Channelized DS3 Interface. Keep in mind that any problems encountered in the test indicate a problem with the connection from the router to the loopback in the network.
By performing tests to loopbacks at various points in the network, you can isolate the source of the problem.