[c-nsp] DS3 mux issues

Justin M. Streiner streiner at cluebyfour.org
Tue Dec 9 17:11:47 EST 2008

On Tue, 9 Dec 2008, Justin Shore wrote:

> In the middle is a new Wide Bank 28 that was set up by one of our telco guys. 
> He said the necessary config is minimal.
> My T3 is up but I'm down/down on the serial ints on both ends.  I can 
> manually loop up the 2811 at the VWIC and the int comes up.  I can loop it up 
> at the biscuit jack on the 2811's side of the mux and the appropriate T1 on 
> the 7206 comes up.  To me that makes me think the mux is fine and that both 
> ends are fine (at least from their perspective). So that makes me think that 
> something isn't matching up on the 7206 and 2811.

Can you loop one of the T1s on the 7206 and see the loop on the 2811?

It's been awhile, but I think this would be done using

controller t3 x/x
  t1 x channel-group 0 timeslots 1-24 loopback ?

There should be a number of different options under this to set the 
direction (facing you or facing the line) and depth (pass through the T1 
framer, etc) for the loop.

I think you may need to have a peek at the config on the mux if possible. 
It looks like your frames aren't passing through, which is probably why 
your T1s are showing LOF/AIS.  When you put a hard loop on the physical T1 
end, facing back to the 7206, do the LOF/AIS indicators go out on that 
port?  From what I can see, the router configs look OK.

Also make sure the mux isn't trying to inject its own clocking into the 
T1s.  It problably isn't, but it's a good idea to check.


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