Multicast how?

[Francisco Obispo]

I'm looking at the Juniper SOW, and I found myself with this:

  a) Multicast demo using VLC.

    i. No Multicast routing functionality will be 
       supported on the CPE. Only IGMP and MLD are 
       to be assumed.


How are we going to get away with supporting Multicast Routing without the multicast routing functionality?, 

Are we planning to do this with IPv6? if not, then MLD is not needed.

I'm envisioning running "pimd" on the CPE so we can join/leave multicast groups, and have the CPE join/leave groups to its upstream router (CGN), something like:



         +----------+
         |   CGN    |
         +----------+
              /\
             /  \
            /    \
   +-------+      +-------+
   | CPE 1 |      | CPE 2 |
   +-------+      +-------+
       |              ^
       v              |
  +----------+   +--------+
  | Receiver |   | Sender |
  +----------+   +--------+


Another option is:

         +----------+   +--------+
         |   CGN    |<--| Sender |
         +----------+   +--------+
              /\
             /  \
            /    \
   +-------+      +-------+
   | CPE 1 |      | CPE 2 |
   +-------+      +-------+
       |              |
       v              v
  +----------+   +----------+
  | Receiver |   | Receiver |
  +----------+   +----------+


In any case, it seems like we're going to need IGMPv2 functionality, with the CGN acting as RP and DR. I'm envisioning that this can be done in Linux, using multicast in dense mode, but it's been a long time since I've tried it, and if I remember correctly, I did it using Cisco equipment, set aside of the default router (they don't need to be the same).

With VLC we can initiate a stream from the sender aimed at a private multicast IP: 239.0.0.0/24 and the receives should join the groups by telling their CPEs that they're interested in that particular IP (at least with IGMPv2-ASM), so they can join the group with their upstream router.

Perhaps it would be interesting to see if we can support ICMPv3 by using SSM (Source Specific Multicast), but I don't think "pimd" supports that as of yet.. (would have to check).

It seems like the main issues here are:

1) Get "pimd" to run in Linux-CPE

2) Get "pimd" running on the CGN receiving+sending 
   requests through the tunnel interfaces

What do you all think?


Francisco Obispo 
email: fobispo at isc.org
Phone: +1 650 423 1374 || INOC-DBA *3557* NOC
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