[c-nsp] Fun problem affecting only even-numbered ports

[Tim Stevenson]

On the fiber (SFP) card, ports are indeed mapped in groups of 12 
consecutive odd/12 consecutive even ports per rohini, with 24 odd 
ports on one janus & 24 even ports on the other.

I'd guess you're just running out of replication bandwidth. A bit 
more detail about the traffic pattern etc would help. How many L3 
replications are occurring here, and for what input rate? Ingress or 
egress replication?

As a general rule you should spread the receivers as evenly as 
possible among odd & even ports to spread the replication load.

Hope that helps,
Tim

At 08:37 AM 10/28/2010, Ben Lovell (belovell) uttered:

>Nothing that I can think of. One Super Santa Anna and Janus run ports
>1-24 and another pair of them run ports 25-48. One Rohini runs each
>consecutive group of 12 ports. The only thing I could guess at is the
>path take across the switchbar fabric but I don't recall how we select
>FPOE right now.
>
>-Ben
>
>On Oct 27, 2010, at 12:54 PM, John Neiberger wrote:
>
> > This is a good one. I'm working with TAC on it, but I thought i'd
> > share it here, too, just because it's so unusual. We're seeing
> > intermittent drops on a multicast video stream and we haven't been
> > able to determine why. This is the second time we've seen this bizarre
> > behavior. At the urging of the TAC engineer, we tried moving receivers
> > to different ports and noticed that we only see the drops when the
> > receiver is connected to even-numbered interfaces! Odd-numbered
> > interfaces are not affected.
> >
> > This is on a 7600 with SUP 720-3BXL and a 6748 linecard. What part of
> > the 6748 linecard architecture is responsible for a behavior
> > difference between odd- and even-numbered ports? This is a WS-6748-SFP
> > with a DFC-3BXL.
> >
> > Any thoughts?
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Tim Stevenson, tstevens at cisco.com
Routing & Switching CCIE #5561
Distinguished Technical Marketing Engineer, Cisco Nexus 7000
Cisco - http://www.cisco.com
IP Phone: 408-526-6759
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