Re: Output Drops on Gig Interface

On Wed, May 5, 2010 at 20:36, naman sharma <naman.prep_at_gmail.com> wrote:
> nope Kambiz i am based out of US..I understand that these drops are less but
> as technical person i would like to know the reason of the drops. I am doing
> some tests.. Will update the group with the status.

Are they seeing the counter increase, or are they observing actual
performance degradation? That's the important thing. Also, the counter
increasing means nothing. The dropped packet, for all we know, could
have dropped because the destination host was no longer present
(dropped out of ARP table just before the packet was sent, but after
it entered the queue - though I doubt this kind of verification is
performed in the queue)... or any corner case like that. What you
should keep an eye on is the RATE if failure, that is ratio of
transmitted and dropped packets. There are dropped packets in *every*
network. If the rate is below certain threshold (and this is almost
10x below it), that's about it.

Now... of course, there is nothing to worry about, but there are
multiple factors that can be causing this. For starters - have you
checked the optics? Are those OK? Have you tried replacing them with
different ones? What are the distances involved - could you be sending
too strong signal (I see you are using LX SFPs and sometimes those
lasers are too strong and could cause performance degradation on the
receiver - you may need attenuators). Could it be too long and you may
need to replace the optics with ZX? Finally... are you using
Cisco-branded (bleh, those were the worst for me) optics or 3rd party
- how reliable is your vendor?

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