[c-nsp] Unicast storms

[Gert Doering]

Hi,

On Mon, Jul 02, 2007 at 01:25:17PM -0400, Pickett, McLean (OCTO) wrote:
> The switch will only timeout the mac table entry if the host has failed to
> generate a single valid frame over the timeout period. The switch will then
> broadcast the first frame destined to the host and re-learn the host mac
> based on its response.
> 
> The ongoing broadcasts should only happen if the mac address in the router's
> cache is no longer valid and does not exist on the network.

Think "two switches, two routers, host being connected to the switch with
the active HSRP router, packets coming in via the other router and the
other switch".

The second switch will only learn the host's MAC address from ARP replies
to the slave HSRP router - once per 4 hours.

Quite common problem, actually.

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