Subject: Mobile + Multicast + Scopes (draft-ietf-ipngwg-scoping-arch-03.txt)

From: Xavier Brouckaert <[email-masked]>
Date: 01 May 2002 00:53:04 +0200

Hello,

In draft-ietf-ipngwg-scoping-arch-03 Section Mobility, authors say : 
"the mobile node MUST NOT try to have a tunnel back into its old zone
for the purposes of attempting such communication".

I think it is quite disappointing to forbid this type of tunnel.  If a
MN is listening to a site-local multicast group, why do you want to
break his communication down when he moves into a foreign network
located outside the mobile nodes' site ?

Scopes aren't great if mobile multicast only works for global scope
communications...

IMHO, a MN should be able to establish a tunnel with his "multicast home
agent" (a home agent involved in multicast routing) to continue
multicast communications out of the current scope.  There should be no
problem for distinguishing two flows from two different sites with the
same multicast address because one flow comes natively on the foreign
network and the other comes through a tunnel.

Is there a way for a mobile node to discover that he has left his
home-site ?  AFAIK, Router Advertisements only contain prefixes, but no
information about scopes.

Regards,
Xavier.

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