[Xorp-hackers] More VRRP problems.

[Ben Greear]

On 03/22/2010 06:32 AM, Li Zhao wrote:
> 1. The first problem, I have had many times now. The code did not have
> cleanup code to revert virtaul MAC, some signal handler function may be
> needed to fix this. But use random MAC is not what RFC want because RFC
> has restricted MAC format. If you use some random format there may be some
> router implementation which rejects to connect to you.

We can be more careful about fixing up the MAC, but cannot in all cases guarantee
we can restore it (kill -9 or fea crash, for instance).

I'd use the random MAC for the 'original' MAC address, after removing the
VRRP MAC.  I would of course make sure the MAC is valid..an easy way being
first octet is zero, rest are random.

Other systems will quickly learn the new MAC because ARP will automatically
start returning the new one..and we could promisc-arp to speed things up.

> 2. I am using virtual machines so I can not play with cables. But if I
> power off the master router, I did see the backup router is taking over
> like the following:

This was due to changes I made:  I was adding the VRRP IP address..and then the
routers thought they 'owned' the IPs.  In split-brain, both 'owned' them.

My preference is to ignore ownership of the IP and just go to backup mode
as normal (immediately removing the IP).  I think this is still OK with
the RFC, though one could argue differently.

I've got a few more changes to my LANforge code before I can properly test
this, but hope to have a working patch later today.

Thanks,
Ben

-- 
Ben Greear <greearb at candelatech.com>
Candela Technologies Inc  http://www.candelatech.com