[c-nsp] 4x10G Etherchannel overruns

[Jean-Francois.Dube at videotron.com]

Hi Peter,

Do the overrun match with input drops on the interfaces input queue? Maybe 
this traffic being punted to CPU?

I had this issue on a Cisco 7600 when using "mpls ldp explicit-null" and 
many Gbps of traffic needed to be sent to CPU.

Hope this helps.

Cheers,

JF

Jean-François Dubé
Technicien, Opérations Réseau IP
Ingénierie Exploitation des Réseaux
Vidéotron 

"cisco-nsp" <cisco-nsp-bounces at puck.nether.net> a écrit sur 2017-03-03 
12:04:28 :

> De : "Peter Kranz" <pkranz at unwiredltd.com>
> A : <cisco-nsp at puck.nether.net>, 
> Date : 2017-03-03 12:09
> Objet : [c-nsp] 4x10G Etherchannel overruns
> Envoyé par : "cisco-nsp" <cisco-nsp-bounces at puck.nether.net>
> 
> 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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