BB Credit transitions from zero

Unanswered Question
Nov 13th, 2009


When I do a sho int fcx/x counters, I can see information that really doesn't make much sense to me and its not explained anywhere that I can easily find.

One in particular is:

<number> bb credit transitions from zero.

I also see the same <number> LLR.

I have 2 x 9509's with ONS 15454 in the middle. Both 9509's are reporting the same number of BB Credit transitions from zero on the ISL (and Port Channel stats) and one switch as <number> for output LRRs and the other switch has <number> for input LRR.

This might be pure coincidence but I want to see if running out of bb credits (which is extremely unlikely over this distance) is causing the LRR events.

I believe LRR events (where is this documented) are caused by some sort of media error outside the 9509 in this case. I can't get any stats on the ONS as the person running them just plain wont look.

I get the feeling that I am getting a glitch in one of the DWDM links but I need to cover all bases.


I have this problem too.
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stephen2615 Fri, 11/20/2009 - 13:28

If anyone is interested in this posting,  I am not running out of BB credits enough to cause LRR's. It could be a pure coincidence and the media links are apparently my problem.

Massive starvation of BB credits will apparently do something along these lines but its not my problem.  Also, an event is supposed to happen if I had starvation of BB credits.  I don't know what it would be but considering the amount of endless syslog events that comes out of the MDS switches, I am sure I would notice something.


inch Mon, 11/23/2009 - 02:38

Hey Stephen,

Attached is a screen grab from a really old slide from networkers...   It describers how/why a lrr occurs.

Jeez, i dunno about this whiz bang web 2.0 version of netpro!!


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