[AG-TECH] IGMPv3, Source Specific Multicast, fully supported in Windows XP

[Jeffrey Eschbach]

Well I'll take a stab at this... Bill or anyone else, feel free to add
to my reply (and correct any errors :).


> Three sites, Foo, Bar, and Nee.  All are sending multicast data to the
> same routable multicast group address.

First off, I think it's important to know if your group address is
within the SSM range or not (typically 232.0.0.0/8).  You will have
different behavior if you use this SSM range versus the remaining ASM
range.  I'll assume the SSM range and therefore no Rendezvous Point
involvement for my reply.


> Foo sends a SSM request to only get traffic from Bar.  Are the following
> true?
> 
> If Bar's edge devices support IGMPv3, no effect since it's traffic is
> being requested.

OK... Bar's traffic will go to Foo.

 
> If Nee's edge devices support IGMPv3 and Foo is the only requestor, then
> the traffic won't leave Nee's network.  If Nee's edge doesn't support
> IGMPv3, the traffic will go onto the backbone.

No traffic should enter the backbone if sending to an SSM address if no
receivers have joined.  I don't think IGMPv3 actually is involved on the
source side... the router just needs to know that it should not forward
traffic in the SSM range unless it has received a join.  (For ASM range,
traffic would go to the RP and then receive a "register stop" to keep
the traffic from leaving the network.)


> If Foo's edge devices support IGMPv3, then Nee's traffic will be
> filtered at the Edge and will not reach Foo.

OK (but see previous answer).

 
> If the edge router for each site supports IGMPv3, if the goal is
> reducing traffic over the backbone and across the Internet2 POP, does it
> matter if the switches behind the edge router support IGMPv3?

I don't think so, as long as your edge device supported IGMPv3.


Hope that helped,
Jeff



 
> -----Original Message-----
> From: Bill Nickless [mailto:nickless at mcs.anl.gov]
> Sent: Thursday, August 15, 2002 10:36 PM
> To: Jay Beavers
> Cc: ag-tech at accessgrid.org
> Subject: Re: [AG-TECH] IGMPv3, Source Specific Multicast, fully
> supported in Windows XP
> 
> At 10:01 PM 8/15/2002 -0700, Jay Beavers wrote:
> 
> >Since I'm not a router bithead, can anyone give me a heads up if I
> should
> >expect SSM to "just work" between Internet2 nodes?  Or might there be
> >complications?
> 
> Hi Jay,
> 
> To answer your specific question: the Internet2 Abilene network is ready
> 
> and capable of running SSM, and has been for well over a year.
> 
> That being said, the problem with SSM deployment revolves around the
> need
> for network edge devices like switches and routers to support IGMPv3.
> It's
> difficult to find Ethernet switches that support IGMPv3, and they're not
> 
> the most economical choices.
> 
> In a strange inversion of the normal situation, the backbone is capable
> of
> SSM service well before the local area networks of the connected sites.
> If
> you can find a site that supports SSM/IGMPv3 locally, it's a pretty good
> 
> bet that they can do SSM with most all other similar sites.
> 
> ===
> Bill Nickless    http://www.mcs.anl.gov/people/nickless      +1 630 252
> 7390
> PGP:0E 0F 16 80 C5 B1 69 52 E1 44 1A A5 0E 1B 74 F7
> nickless at mcs.anl.gov

-- 
----------------------------------------------------------------
Jeff Eschbach                              eschbach at motorola.com
Networks and Infrastructure Research
Senior Staff Engineer, Motorola Labs Internet2 Initiative
http://internet2.motlabs.com              Fax:    (847) 576-3240
Desk: (847) 538-5846                      Mobile: (847) 980-2240