[rbridge] Global MAC Addresses

[Caitlin Bestler]

Eric Gray (LO/EUS) wrote:

> 
>> 
>> Without explicitly stating it, the current draft recognizes that
>> because RBridges *share* data amongst themselves that they will find
>> it challenging to do so without sharing semantics as well.
>> Having RBridges disagree on whether the VLAN-ID is a key field or an
>> attribute field could create some interesting problems.
>> And there is certainly strong rationale for standardizing on the
>> VLAN-ID as key field approach.
> 
> Agreed.  A specification draft cannot be ambivalent on issues
> of this nature.
> 
> Are you saying that is what is happening here?  Can you give
> specific text examples where this is happening?
> 

If RBridge R learns of MAC X on VLAN Y that information is explicitly
NOT forwarded to RBridge S unless RBridge S is not part of VLAN Y.

If RBridge S has MAC X as belonging to VLAN Z then we would have
a conflict if either of the RBridges considered the "L2 Key" to
be just the MAC address. Nominally global IPv6 addresses which 
actually reach *different* destinations.

Such conflicts were much more benign when bridges merely forwarded
packets and didn't forward location data.

There enumeration of RBridge retained data also states that L2
and L2/L3 tracking data is per-VLAN.

The justification for this is that "global" MAC addresses are in
fact not global. That's counter-intuitive enough that I think it
at least needs to be explicitly noted.