[Info-vax] PEA0: Errors

[Christoph Gartmann]

In article <009f2623$0$26924$c3e8da3 at news.astraweb.com>, JF Mezei <jfmezei.spamnot at vaxination.ca> writes:
>Christoph Gartmann wrote:
>
>> Yes, the switch tells something about excessive collisions and drop rates.
>
>For full duplex links, you shouldn't have collisions. Are you sure both
>sides of each link (switch and computer) have proper settings or auto
>negotiation ?

Both, the VMS boxes and the switch are set to fixed rates. The Alphas have
100MB/FD while the VAXen use 10MB/HD. One strange thing is that one Alpha
needs "auto negotiation" on the switch, otherwise the connection is flaky.

>Note that for half duplex links on switches, having collisions is
>normal. It just means that the switch detected the link being used in
>the other direction before attempting to send a packet, so it delayed
>that packet (and increased the collision number).

This is clear. But what does this HP switch mean when it states "drops"?
>From the number of drops I assume these are the collisions. On the other
hand collisions are explicitely mentioned when looking at a port in detail.
The collisions are considerably lower than the drops...

>> Meanwhile I think I found the reason: the packet sniffer shows that it is an
>> antispam box that produces huge amounts of illegal tcp sequence numbers every
>> 37 minutes so that the switch gets overwhelmed :-( This box communicates
>> with one of the cluster members in order to deliver mail.
>
>Depending on the sophistication level of your switch, you could possibly
>give SCS traffic greater priority than IP traffic, in which case, that
>IP box's tamper tantrum wouldn't prevent SCS traffic from being delivered.

This sounds interesting. I will have a look into this.

Regards,
   Christoph Gartmann

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