RE: [Bridge] Multicast

["Tomo Ceferin" <tomo@activetools.si>]

True. However, allow me to make two assumptions (true in our case):
1) Bridge implements set_multicast_list() and uses it to learn multicast
groups.
2) IPv4 or IPv6 is attached to bridge - both provide IGMP snooping which in
turn feeds bridge with multicast lists through set_multicast_list().

With both above assumptions true, bridge now has awareness of which ports
belong to which multicast groups, hence removing the need to flood all ports.

Am I getting something wrong?

Tomo

> -----Original Message-----
> From: Guillermo Ibáñez
> 
> Just an explanation to distinguish processing of layer 3 multicast 
> packets (by routers) from layer 2 multicast frames (by 
> bridges).  Due to 
> the fact that the multicast MAC addresses are not permitted in the 
> Ethernet frame as source addresses, multicast MAC addresses 
> can not be 
> learnt by the bridges, so the processing of multicast addresses by 
> bridges consists in broadcasting, flooding frames in all but source 
> port, instead of forwarding them only by ports where these addresses 
> were learnt.
> Excuse me if it sounds a bit "academic".
> GI