Do we ever want to bind more than 8 multicast MAC addresses?

Polychronis Ypodimatopoulos ypod at
Fri Apr 18 12:08:49 EDT 2008

David Woodhouse wrote:
> On Fri, 2008-04-18 at 12:01 -0400, Polychronis Ypodimatopoulos wrote:
>> You're not following: Ethernet ports are bytes 12-14 (2 bytes total) on 
>> _all_ ethernet frames. IP has nothing to do with this. Instead of 
>> looking at the first 6 bytes (destination mac) for a specific multicast 
>> address, the filter should be looking at bytes 12-14 for a specific 
>> ethernet port.
> Ah, sorry. I read it as UDP ports.
> It would be hard to do this -- there's a defined mapping from IPv6
> addresses to the multicast MAC addresses used, and high-level
> applications don't get to muck around with low-level details of the
> Ethernet frames.
Dynamic mapping from a single 6-byte address to multiple 16-byte 
addresses? I'm curious how this works. I just hope you don't have to 
change your IPv6 address every now and then ;-)

Salut is _no_ high-level application and it should _not_ be associating 
multicast addresses with activities.


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