Re: [nsp] a question on irreguler latency

From: Dmitri Kalintsev (dek@hades.uz)
Date: Sun Oct 21 2001 - 22:21:13 EDT


What is your queing method on this interface? Although your 30 sec
utilisation may be around 20%, you may very easily be getting bursts peaking
at 100%, which may cause what you see. Try to configure (d)(W)RED and see
if this helps.

In case of 7500, it would be something like:

!
class-map match-any xyz
  match any
!
policy-map something
  class xyz
    bandwidth percent 99
    fair-q
    random-de
!
int Type X/Y/Z
 service-po out something
!

(I would try this in the lab first, before trying to roll this out into live
network, of course). ;)

Not sure though, how it's gonna handle anything faster than 2Mbps, though.
Maybe somebody from Cisco wants to comment?

On Thu, Oct 18, 2001 at 08:08:20AM -0400, Tatsuya Kawasaki wrote:
> Cisco Gru,
>
> I noticed OC3/OC2 via Sonet across the country does seem to have
> consistant latency but for some strange reason for DS3 seems to have
> very irregular latency.. for the most time under 12ms but it takes as much
> as 600ms I do not understand why.
> it seems that band utlization is under 20% for 30 sec. average
> I have found cisco bug report, CSCdr86800, it says..
> When using two PA-A3-OC3MM port adapters in the same Versatile Interface
> Processor 2-50 (VIP2-50) module in a Cisco 7500/RSP series router, some
> packets through one port adapter might be delayed up to a second. There
> is no workaround
>
> It is not a quite the same situation but I wonder if anyone can help me.
>
>
> Sincerely yours,
>
> Tatsuya
>
> /_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/
> Tatsuya Kawasaki
> Allegiance Telecom
> Unlock the Power of the Internet
> http://www.kivex.com
> Phone 301.215.6777 Fax 301.215.5991
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---end quoted text---

-- 
 CCNP, CCDP (R&S)                          Dmitri E. Kalintsev
 CDPlayer@irc               Network Architect @ connect.com.au
 dek @ connect.com.au    phone: +61 3 9674 3913 fax: 9251 3666
 http://-UNAVAIL-         UIN:7150410    cell: +61 414 821 382



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