RE: Total Output Drop on C2960G interface

Dear all,

May i re-ask this question again ? The previos information may make someone confused, due to many output result.

--
As I observed dropping txqueue statistics,
C2960G# show platform port-asic stats drop gigabitEthernet 0/42
 
  Interface Gi0/42 TxQueue Drop Statistics
    Queue 0
      Weight 0 Frames 0
      Weight 1 Frames 0
      Weight 2 Frames 0
    Queue 1
      Weight 0 Frames 0
      Weight 1 Frames 0
      Weight 2 Frames 0
    Queue 2
      Weight 0 Frames 0
      Weight 1 Frames 0
      Weight 2 Frames 0
    Queue 3
      Weight 0 Frames 0
      Weight 1 Frames 0
      Weight 2 Frames 43279243
Even, MLS QOS not yet enabled,
Does this problem related to ASIC Egress Queue or not ?
 
Can i solve by changing queue-set's threshold ?
 
mls qos queue-set output 1 threshold 4 400 400 50 400
 
If yes, can you reccomend this threshold value ?
Best regards,
Satit  Chanoupragan
> Date: Mon, 25 Oct 2010 09:23:25 +1100
> Subject: Re: Total Output Drop on C2960G interface
> From: martin.john.hogan_at_gmail.com
> To: dale.shaw_at_gmail.com
> CC: rslab007_at_gmail.com; satitcha_at_hotmail.com; ccielab_at_groupstudy.com
> 
> +1 what Dale said;
> 
> When you have a 2960 or similar switch with small buffers and the inbound
> rate > outbound rate because for example you have 4 interfaces receiving
> data from hosts and a singular outbound interface, even if only for a very
> short time (micro-burst) you will see output drops.
> 
> Potential solution: Increase outbound bandwidth capacity (Etherchannel etc)
> 
> 
> 
> 
> 
> 
> On Mon, Oct 25, 2010 at 8:13 AM, Dale Shaw <dale.shaw_at_gmail.com> wrote:
> 
> > 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
> >
> >
> > Blogs and organic groups at http://www.ccie.net
> >
> > _______________________________________________________________________
> > Subscription information may be found at:
> > http://www.groupstudy.com/list/CCIELab.html
> 
> 
> Blogs and organic groups at http://www.ccie.net
> 
> _______________________________________________________________________
> Subscription information may be found at: 
> http://www.groupstudy.com/list/CCIELab.html
Blogs and organic groups at http://www.ccie.net