[c-nsp] Re-thinking (remembering) how a switch operates

[Gert Doering]

Hi,

On Wed, Apr 27, 2005 at 10:21:55PM -0400, Jeff Kell wrote:
> The syslog server just sits and logs traffic.  As a general rule, it
> never transmits anything.  The switches, therefore, only very rarely see
> it's mac as a source address, so they never learn the mac entry.  

Yeah, very common problem.  

We've seen this with a news server (fairly busy) whose output traffic 
went - due to router and switch redundancy - via a different switch path 
than the ingress traffic, and such the ingress traffic was flooded
all over the ingress switch...

Our solution was to run rwhod on all boxes.  Send out a controlled
broadcast every 60 seconds, make sure CAM tables on all switches are
refreshed (Cisco default aging is 90 seconds, IIRC).

gert

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Gert Doering - Munich, Germany                             gert at greenie.muc.de
fax: +49-89-35655025                        gert at net.informatik.tu-muenchen.de