[Nottingham] NIC MACs aliases & IP aliases

[Matthew Walster]

2009/3/26 Graeme Fowler <graeme at graemef.net>:
> On Thu, 2009-03-26 at 14:50 +0000, Matthew Walster wrote:
>> Yes. This is how networks using VRRP make sure that you have near-100%
>> uptime when you take the primary default gateway down.
>
> That's not *quite* correct. VRRP (Virtual Router Replacement Protocol)
> doesn't do any form of MAC manipulation; it simply moves the active IP
> address between nodes when failover happens and then sends GARP
> (Gratuitous ARP) packets to the local network saying "I'm Spartacus",
> like this:

Juniper does it wrong then ;)

What I see is that the virtual MAC hops from one router to the other.

i.e. On my test box:

89-145-107-1.as29017.net (89.145.107.1) at 00:00:5e:00:01:00 [ether]
on eth0 [VRRP Virtual]
89-145-107-2.as29017.net (89.145.107.2) at 00:21:59:0e:7d:2b [ether]
on eth0 [VRRP Master]
89-145-107-3.as29017.net (89.145.107.3) at 00:21:59:0e:35:2b [ether]
on eth0 [VRRP Backup]

I thought the GARP packets were to update the MAC forwarding tables on
switches, as opposed to updating the actual ARP entry?

Maybe I'm wrong...

M