[c-nsp] Constant output drops on etherchannel

[Dan Letkeman]

3560 or 3560G.

(C3560-IPSERVICESK9-M), Version 12.2(53)SE2

Interface config:

interface Port-channel2
 switchport trunk encapsulation dot1q
 switchport trunk native vlan 3009
 switchport trunk allowed vlan 8,10,1008,1101,3009
 switchport mode trunk
end

I see more output drops during higher traffic, but I still see drops
during low traffic rates.  Always more on one interface.

I do have auto qos enabled for some of the phones I have connected to
the switches, but I don't have any qos on the etherchannel trunks.

I'm just using the default etherchannel load balancing algorithm.

Thanks,
Dan.


On Fri, Jan 14, 2011 at 10:12 AM, Phil Mayers <p.mayers at imperial.ac.uk> wrote:
> On 14/01/11 16:08, Dan Letkeman wrote:
>>
>> Hello,
>>
>> I'm seeing many of our etherchannel's on different switches having output
>> drops:
>
> Platform? IOS version? Config of the interface(s) (routed, SVI, etc.)
>
>>   Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops:
>> 898085
>
> Are you monitoring the traffic rate? Do the drops correspond to traffic
> bursts? Do you have QoS enabled?
>
>> I also see that it usually uses one port of the etherchannel to a high
>> degree, say 92% before it seems to push data through the other
>> connection.
>
> That's not necessarily unusual, depending on your etherchannel load
> balancing algorithm and traffic patterns. But you haven't really supplied
> enough info for people to help you.
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