Re: Total Output Drop on C2960G interface

Hi,

On Mon, Oct 25, 2010 at 6:52 AM, Abdul <rslab007_at_gmail.com> wrote:
> Output que drops are a function of the recipient host (in your case, the firewall) unable to keep up with the data that is being sent by the switch. I am sure if you have the switchport enabled to send and receive Ethernet pause frames, you would see the a ton of input frames coming from the firewall.
>
> This problem isn't with your switch unable to keep up. It's with your firewall. Sure you could do things like policing your outbound traffic, but your probably better taking a more higher scope view as to what is the best QOS policies would be best suited and where (i.e where to mark your traffic) in your environment. Then executing your policies.

I have to disagree. Output drops are caused when the switch runs out
of buffers. 2960 is notoriously bad at coping with bursty traffic. I
doubt it's got much at all to do with the firewall.

Also, I recently read a post suggesting that enabling QoS on a 2960 is
very likely to make it problem worse because it essentially causes the
small amount of buffers to be carved up between 4 tx queues (I have no
hands-on experience with c2960 so this is not authoritative).

Cheers,
Dale

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Received on Mon Oct 25 2010 - 08:13:53 ART