Re: Packet loss problem

From: Basil V. Dolmatov (dol@east.ru)
Date: Thu Jan 06 2000 - 17:03:56 EST


On Thu, 6 Jan 2000, Steve Pfister wrote:

> On the router that has the two different subnets out one FastEthernet port
> (a 2621 with a 1-port Ethernet card), none of the interfaces are showing
> any input or output drops. The 'show buffers' command shows some failures,
> but these aren't increasing terribly much over time. There are quite a few
There should be none, increase corresponding buffer's defaults.

> collisions on the Ethernet port, usually totalling about 6-9% of packets
That's a lot... Switch on full-duplex and put Interface to _switched_
9not hubbed) port).

> output. In times of high traffic, throughput for other data streams is
> noticably reduced. In the output of 'show process cpu,' the totals at the
> top seem kind of high (to me at least), for example, five seconds: 38%/16%;
> one minute: 22%; five minutes: 20%. The other figures in the list below
> that don't really seem to change much from more idle times.
>
> The problem actually was worse, and adding 'ip route-cache same-interface'
> to the FastEthernet port made things a little better, but the problem is
> still there.
>
> Do we need a new router? Maybe more memory for the current one (it seems to
> usually have 800k - 1.2mb free at any one time)? Do we need to tune the
> buffer settings?
Yes. You need:

 - tune the buffers
 - switch on full-duplex
 - put router Ethernets to switched ports not to hubs
 - keep "ip route-cache" and "ip route-cache same interface" in config.
 - if you use policy prouting place "ip route-cache policy" on
   necessary interfaces

>

---------------------------------------------------------
Basil (Vasily) Dolmatov CCIE #5347, CCNP-Security, CCDA
East Connection ISP, Moscow, Russia. (http://www.east.ru)



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