[c-nsp] Forgetting switch

[Gert Doering]

Hi,

On Mon, Nov 08, 2004 at 06:56:54PM -0600, John Kristoff wrote:
> > How does this sort of problem ("router still has ARP entry, but switch has
> > forgotten MAC address") usually get fixed? I have the option of increasing
> 
> Some solutions have already been posted, but another is to ensure the
> host periodically generates traffic so the bridge will refresh it's
> address tables.  If it's a critical server/interface it might make sense
> to periodically monitor it with your network management system for example.

Unfortunately, this might not really help - in this situation, the machine
is generating traffic all the time, but due to the way the packets flow
through the switches, one of the switches will never see packets sourced
by "host A" - so all packets sent by other hosts on this switch will
have to be flooded.

> Taking the opposite approach, you could also have the box push out a
> 'beacon' packet itself via a reguarly scheduled cron job.

The 'beacon' needs to be broadcasted to really be visible on all switches
in the ethernet cloud.  But otherwise this was also the solution we found
(rwhod broadcasts).

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