Re: Virtual MAC really necessary?

The advantage of the virtual mac is that it is a multicast address so both 
devices should receive the traffic regardless of their failover state. 
Also, the virtual mac allows failover with out any of the devices having 
to change their arp entry.  The gratuitous arp just serves to update the 
forwarding table in the switch(s).  If the gateway mac was suddenly a 
physical address you may run into issues if some of the attached devices 
don't receive the gratuitous arp or don't process it because of security.

 



"Roland Abt" <[email protected]> 
01/14/08 11:31 AM

To
[email protected]
cc

Subject
[VRRP] Virtual MAC really necessary?






Hello everybody

I want to implement my own VRRP protocol. The protocol itself is not that 
tricky, but using a virtual MAC seems like a big hurdle to me. The 
standard states that the MAC address of the new Master has to be published 
 
in a gratuitous ARP (request/reply). I think this already should help to 
update the ARP table of every device. Does anybody know of a situation 
where publishing the physical MAC would cause any trouble? Are there any 
known devices that would not update their ARP table in case of such a 
gratuitous ARP?

Best regards and thanks in advance for your time,
Roland


PS:
According to the Ethereal Wiki (http://wiki.ethereal.com/Gratuitous_ARP) a 
 
gratuitous ARP can be either a request or a reply. Any experience which 
one is better?

_______________________________________________
vrrp mailing list
[email protected]
https://www1.ietf.org/mailman/listinfo/vrrp

_______________________________________________
vrrp mailing list
[email protected]
https://www1.ietf.org/mailman/listinfo/vrrp