[c-nsp] 4x10G Etherchannel overruns

[Peter Kranz]

On a WS-X6908-10G DCEF2T line card with SUP2T's, I ran into overruns
yesterday on a 4x10G etherchannel that I am at a loss to resolve:

 

Constantly increasing overrun counter:

   6418130558941 packets input, 9277559958229871 bytes, 0 no buffer

     Received 668274 broadcasts (0 IP multicasts)

     0 runts, 190 giants, 0 throttles

     192 input errors, 1 CRC, 0 frame, 51591389 overrun, 0 ignored

 

Latency into the router rose by 40ms when these overrun's started to appear

 

This happened at a BW of ~28 Gbps 

 

I've built the etherchannel in this manner:

 

Index   Load      Port          EC state       No of bits

------+------+------------+------------------+-----------

0      0A            Te1/1             Active   2

3      81            Te1/2             Active   2

1      60            Te1/3             Active   2

2      14            Te1/4             Active   2

 

Is it necessary to instead stagger 1/1, 1/3, 1/5, 1/7 to spread the load
across the card ASICs? I didn't think the WS-X6908 was an oversubscribed
card so didn't bother initially.

 

Peter Kranz
www.UnwiredLtd.com <http://www.unwiredltd.com/> 
Desk: 510-868-1614 x100
Mobile: 510-207-0000
pkranz at unwiredltd.com <mailto:pkranz at unwiredltd.com>