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

[Benjamin Lovell]

Ahh. I was looking at the block diagram for the GE-TX and just assumed  
it was the same for SFP.

Thanx for the correction.

-Ben

On Oct 28, 2010, at 12:10 PM, Tim Stevenson wrote:

> 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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