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6608 blade and T1 loopback cable

Does anyone know why a regular T1 loop plug/test cable won't bring up a T1 on a 6608 blade set for internal clocking? Can not seem to locate any docs that tell limiations of the T1s on this.

Have tried it on my lab 6608 and client has tried to and doesn't work when they were trying to test a port. They argue a standard T1 loop cable should work since it is a T1 port. In past, I've also had issues with T1 crossover connecting to some equipment and it seems the 6608 is picky and wants the T1 to be coming from telco or other end terminated from a real CSU/DSU interface. They were trying to use the spare T1 port they had to connect to a modem pool server.


Re: 6608 blade and T1 loopback cable


Just tested it and T1 loopback works in 6608 load D00403030018 with native 12.1(26)E5 code.

Voice Gateways section of Troubleshooting Cisco IPT book indicates to configure 6608 as the network side, enable 'debug isdn q931', and do a shut/no shut on the controller. When the gateway transmits the SAMBE it should return:

RX <- BAD FRAME (0x00017F)Line may be looped!

This indicates the loopback is working.

Hope that helps a little.



Re: 6608 blade and T1 loopback cable

The only way I know of to enable a loopback on a 6608 port is by using the DickTracy tool and running commands, like:

4 set loopback

x is either:

0 - none

1 - local

2 - payload

5 - remote

Download Dick Tracy from here.

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