local loop ttesting

Unanswered Question
Oct 21st, 2007

hi all,

can someone explain or present documentation how to perform loopback testing?

and which test has to perform to ensure that particular device is working fine?

upon which types of connections methods does i can perform this test.

I have this problem too.
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bvsnarayana03 Mon, 10/22/2007 - 00:26

Is it the link & the interface testing u r talking about.

For link testing, local loop is given on router interface initiated from modem. If loop is observed on interface, then local connectivity is considered ok.

Remote loop to remote device is also initiated from the modem. If the loop is observed than end to end connectivity is considered to be fine.

Interface testing: connect the router cable to the interfaces to be tested on router. Assing one interface as DTE & the other interface as DCE. Assing IP & check with ping for connectivity. +ve test indicates that interfaces are working fine.

bethamprashanth Tue, 10/30/2007 - 23:58

hi narayana,

thanks for response, but i have one basic question how to observe loop on interface.

ilya.varlashkin Mon, 10/22/2007 - 02:41

Perhaps one of the following documents will help:

1. “DS1, T1 and E1 Glossary”, Cisco Document-ID 25540


2. “E1 Troubleshooting”, Cisco Document-ID 14163


3. “E1 Layer 1 Troubleshooting Flowchart”, Cisco Document-ID 9320


4. “E1 Error Events Troubleshooting”, Cisco Document-ID 9319


5. “E1 Alarm Troubleshooting”, Cisco Document-ID 14158


6. “Hard Plug Loopback Tests for E1 Lines”, Cisco Document-ID 14165


7. “E3 Troubleshooting Flowchart”, Cisco Document-ID 22880


8. “E3 Error Events Troubleshooting”, Cisco Document-ID 22882


9. “E3 Alarm Troubleshooting”, Cisco Document-ID 22881


If you don't get access to them, try searching CCO by respective title and or cisco document-id.

bethamprashanth Tue, 10/30/2007 - 23:41

hi all,

sorry for delayed response. ur responses were very helpfull.

i have other question:

what are generally used v.35 modems?

appreciated, if given a detail of all modem that are generally used for various wan technologies.


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