Subject: [magma] SSM vs ASM and IGMPv3 reports

From: John Zwiebel <[email-masked]>
Date: Wed, 28 Jun 2006 15:11:01 -0700

This was my last statement in an email I sent in the thread:
   Subject: 	Re: mboned: RE: [magma] suggestion for simplifying  
IGMPV3/MLDV2 to discard EXCLUDEmode

I figure it needs a thread of its own...

ONE LAST POINT:  (hmmm... I'll put this into a separate email, please
   don't respond on this thread.)
The v3-lite spec discusses ASM and SSM.  Like Dino, I think SSM is well
defined, but ASM is not.  But reading the spec, I need to ask how an
SSM group range is allocated.  We know that currently it defaults to
232/8, but that routers can configure locally it for any range.  Routers
specifically reject (*,G) IGMP host reports for groups in the SSM range.
AND routers -reject- (S,G) IGMP host reports for ASM groups.

The spec combines ASM and SSM in a way that suggests to me that at  
least some
of you would be "surprised" to see this.

You would expect an ALLOW (224.1.1.1,1.1.1.1) to create an IGMP cache  
entry
and trigger a (S,G) join even though the router is specifically  
configured to
treat this as a PIM-sparse group  (Note, can't say ASM since -- in  
some circles --
that includes Bi-dir, and I certainly don't want to send (S,G) joins  
for a bidir group).

John Zwiebel

_______________________________________________
magma mailing list
[email-masked]
https://www1.ietf.org/mailman/listinfo/magma