[rbridge] AF change handling

[Suresh Boddapati]

>  
> Donald, can it simplified to have an "optional" TLV
> per VLAN-x that
> contains
> the "AF-gen-id" of that RBridge? Each time AFness of
> an RBridge changes
> for VLAN-x
> on any of its port, it can increase its AF-gen-id by
> 1 for that VLAN-x
> in its LSP. 
> Recipients can "optionally" process the AF-gen-id
> TLV to shorten the
> cache timer 
> as you have stated.
> 

I like this idea. This can be optimized a bit to
change the gen-ID only when the RBridge moves from AF
to non-AF on any of its ports. When an RBridge changes
from non-AF to AF on any of its ports, nothing needs
to be done, since there are no MAC addresses to
unlearn. So maybe you could call this "AF-lost-GenID"
or "AF-lost-counter". 

Suresh