comment on draft-ietf-v6ops-bb-deployment-scenarios-01.txt on the cabe modem section

[Alain Durand <alain@tycool.net>]

I have some comments on the cable modem scenario.

- the various sub-scenarios have a lot in common. The way there are 
described in full one by one makes
that there is a lot of redundant text. Grouping commonalities in one 
section and ten, for each sub-case,
describing what is different would make the document easier to read.

- There is something not obvious on why IGMPv3/MLDv2 is needed.
  the CM amd CMTS are L2 bridges, so they could just forward any 
multicast traffic.
  This is especially true for the CM, which has only 2 interfaces. I 
reckon it may be
   different for the CMTS is one wants to make sure multicast traffic 
for one customer
   does not accidentally flows to another. In any case, I'd like to see 
some more
   text why MLD is needed. Actually the current text is a bit 
ambiquous, it some
   places it says that MLD is mandatory, in other it just says that the 
absence of MLD "could"
   break ND...

- If a cable operator decides to roll out v6 for management purpose, 
then all the scenarios
 about using tunnels are moot, unless the home GWR does not support v6.

- If v6 multicast is important, support for MLD proxy or PIM-SM is critical
 in the GWR. If it is not there, is there a work around?

   - Alain.