[c-nsp] Constant output drops on etherchannel

[Peter Rathlev]

On Fri, 2011-01-14 at 12:28 -0600, Dan Letkeman wrote:
> 3560 or 3560G.
> 
> (C3560-IPSERVICESK9-M), Version 12.2(53)SE2

There have been extensive dialogue about (the lack of) buffering on that
platform on this very list many times. Search the archives or Google to
find out.

> 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.

You can't configure QoS on the port-channels on the 3560, so the
interesting part is the physical interfaces.

Auto-QoS is IMHO a very bad idea on this platform; you carve your
buffers up in a very non-optimal fashion that way.

-- 
Peter