[c-nsp] 7500 Channelized DS3 Issues

[Pete Templin]

Todd Shipway wrote:

> DS3 card is divided into multiple T1 interfaces.  All interfaces have
> been running without problems for weeks.  Last week 1 interface went
> down, and when it came back up, no traffic will go across the interface.
> The int shows as up/up, manually setting a route doesn't help anything.
> Copying the int config to a different channel on the same card fixes the
> issue and traffic is back to normal.
> 
> Today, we had 2 interfaces that were part of a multilink ppp interface
> go down and right back up.  All interfaces were up/up including the
> MLPPP interface.  Moving them to different channels resulted in the same
> issue.  Moving 1 T1 to a Multi-channel T1 card and keeping the other T1
> on the channelized DS3 allowed the multilink interface to come up and
> traffic went back to normal. 

Usual questions first: what chassis, what RSP, what IPs/VIPs/PAs, 
particularly for the DS3 work, what IOS, and why have you selected that IOS?

I had odd problems with 7507/RSP4+RSP4/VIP2-50+PA-FE-TX/VIP2-50+PA-FE-TX 
VIP2-50+PA-MC-2T3+ boxes on IOS 12.0(27)S1 back in the day.  "Something" 
would happen, and one T3 port would stop passing traffic.  RMA on the 
PA-MC-2T3 helped, but 12.0(27)S3 made all the difference (and 12.0(27)S5 
has been even better).  We chose 12.0(27)S back then as it was perhaps 
the newest 12.0S at the time and seemed to have the general following 
for CT3 work.  We've tried 12.0(31)S (for various rebuilds of that S) 
with very poor success on Ethernet work, and have left 12.0(27)S5 in 
place for CT3s ever since.  It's as close to "set and let" as we've ever 
seen with 7507s.

Pete