[c-nsp] "Total output drops" - congestion ? - 7200-VXR

[Rolf Mendelsohn]

Hi Guys,

This really depends on the speed of the Interface and what is connected on the 
other side.

We had a Serial Satellite link of 5M, which was never running higher than 
4.5M - due to regular bursty traffic.

After increasing the queue (fair-queue 320 256 0) the link now does about 
4.9M, without drops & without any significant increase in latency.

I guess the default WFQ size might be a bit small for some links.
I also think that hold-queue is only relevant if you are using FIFO queuing.

Alternatively WRR queuing could help.

cheers
/rolf

On Wednesday 16 July 2008 16:41:15 David Freedman wrote:
> It is inadvisable to increase the output hold-queue as far as I am
> aware, this could cause packets to be delayed on egress which could
> cause TCP timeouts.
>
> Dave.
>
> Farhan Jaffer wrote:
> > Have you tried 'hold-queue ...' command. This may resolves your problem.
> >
> >
> > On Wed, Jul 16, 2008 at 11:22 AM, Wilkinson, Alex
> >
> > <alex.wilkinson at dsto.defence.gov.au> wrote:
> >> Hi all,
> >>
> >> I am having problems with a particular device going down every 3-4 days.
> >> The switchport for which this device is connected to is telling me it is
> >> having a lot of "output drops" e.g.
> >>
> >>   Input queue: 0/2000/0/0 (size/max/drops/flushes); Total output drops:
> >> 13342805
> >>
> >> I 'suspect' that these output drops could be the root cause of the
> >> device attached to this port going down consistently.
> >>
> >> Question: Since 'output drops' seems to relate to interface congestion
> >> can anyone recommed a tool to 'blast' this particular interface in order
> >> to test {in,out}queues and congestion ?
> >>
> >>  -aW
> >>
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