[c-nsp] 4x10G Etherchannel overruns

[Paul]

Overruns on 6500 platform ingress usually means there's nowhere to send 
the traffic coming in (i.e. whatever port it's trying to send the 
traffic TO is overloaded with output drops or the fabric is full to the 
egress port).  So check where the traffic is going (like if it's going 
to a 1g port ingressing on this 4x 10g)


On 3/3/2017 12:04 PM, Peter Kranz wrote:
> 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>
>
>   
>
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