[c-nsp] multicast on layer 2

[Gert Doering]

Hi,

On Wed, Jun 29, 2005 at 10:25:26AM -0400, Andrew K Ho wrote:
> Howevever, sources do send membership reports.  

Only if they also want to listen to the group in question (= being
"source and receiver" at the same time).

Source-only hosts don't need to do IGMP.

> I'm thrown off by the fact 
> that the multicast session never goes past the first hop router, hence, 
> there should be no need for the router to participate in the multicast 
> session.

Indeed.

The router is only going to be important if you want to limit the spread
of the multicast packets (read: not flood them everywhere) - in that
case, the way current switches do it requires assistance from the
routers.  But as the original poster said this is not a requirement,
having a router or not should not make a difference.

gert

-- 
Gert Doering
Mobile communications ... right now writing from * Isola dei Gabbiani *