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RE: PSINet/Cogent Latency

  • From: Alex Rubenstein
  • Date: Tue Jul 23 00:11:57 2002

An effective way would to graph queue drops:

Serial4/1/1 is up, line protocol is up
  Description: to PSI via 3x-xxx-xxx-xxxx
  Internet address is 154.13.64.22/30
  Last clearing of "show interface" counters 5w4d
  Queueing strategy: fifo
  Output queue 0/40, 2275 drops; input queue 0/75, 0 drops

  30 second input rate 5000 bits/sec, 6 packets/sec
  30 second output rate 39911000 bits/sec, 4697 packets/sec
     144472370 packets input, 2769590243 bytes, 0 no buffer
     Received 0 broadcasts, 0 runts, 1 giants, 0 throttles
              0 parity
     5 input errors, 5 CRC, 0 frame, 0 overrun, 1 ignored, 0 abort
     1969955129 packets output, 430008350 bytes, 0 underruns


FYI, for those of you commenting on my full PSI pipe, with a very small
queue depth of only 40 packets, we've seen 0.00011548% percent drop -- 1
in every 865914 packets sent. Agreed, not 0%, but still, arguably that
would never, ever be noticed by anyone.

Once again, I don't condone; however, 1/10000th of a percent of packet
loss is easily worth the decreased cost in traffic sent to this endpoint.

Anyone disagree?

(an important a seperate note is that CAR/CEF drops due to ICMP reaching
over 10 mb/s would trigger the same counter)





On Mon, 22 Jul 2002, [email protected] wrote:

>
> Is there patch or special config example available that would allow me to
> use mrtg (or rather rrdtool) to measure more often and then graph it in a
> way that would show standard 5-min graph but also separate line showing
> those micro burst and actual peak usage?
>
> On Mon, 22 Jul 2002, Randy Bush wrote:
>
> >
> > > 40mb/s isn't "loaded" for a DS3?
> >
> > if you are measuring 40mb at five min intervals, micro peaks are pegged out
> > causing serious packet loss.
> >
> > randy
> >
>

-- Alex Rubenstein, AR97, K2AHR, [email protected], latency, Al Reuben --
--    Net Access Corporation, 800-NET-ME-36, http://www.nac.net   --