US patent 5473599

Henning Brauer hb-nanog at
Thu May 8 11:09:38 UTC 2014

* Nick Hilliard <nick at> [2014-05-08 13:03]:
> On 08/05/2014 11:25, Henning Brauer wrote:
> > you shouldn't see issues but log spam.
> maybe you misunderstand the problem.  If you have vrrp and carp on the same
> vlan, using the same vrrp group ID as VHID, then each virtual IP will arp
> for the same mac address on that vlan.


> This messes up the switch's forwarding table for that particular vlan
> because it sees multiple entries from different ports for the same mac
> address.


my switches seem to deal with that, wether they have special handling
for that mac addr range or not i dunno.

again, stress the fact that afair we have gotten zero reports about
that "issue" for 10 years, it obviously means that either
1) a vast majority of switches deal with it just fine
2) people know that vhids shouldn't clash and avoid that

Henning Brauer, hb at, henning at
BS Web Services GmbH, AG Hamburg HRB 128289,
Full-Service ISP - Secure Hosting, Mail and DNS Services
Dedicated Servers, Rootservers, VMs/PVS, Application Hosting

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