Subject: remarks- source specific multicast for IP

From: Ali Boudani <[email-masked]>
Date: Wed, 28 Feb 2001 18:52:13 +0100

Hello,
just a few remarks
1- Elimination of cross-delivery of traffic when two sources
    simultaneously use the same source-specific destination address.
    The simultaneous use of an SSM destination address by multiple
    sources is explicitly supported.

You are supposing that the delivery is done usually by shared tree??
but in all cases the use of ssm will not eliminate the cross-delivery
because it is not a protocol matter more than topology matter??
isnt true?

2- the adding of SSM upgrades to the existing protocol hasnt any impact
in scalability in building multicast trees??

3- is the source address should be in teh range 232/8 also or it is just
for the group ??

Thanx

---

From: Hugh Holbrook <[email-masked]>
Date: Wed, 28 Feb 2001 10:42:15 -0800 (PST)

> Date: Wed, 28 Feb 2001 18:52:13 +0100
> From: Ali Boudani <[email-masked]>
> 
> Hello,
> just a few remarks

We're referring to the property that subscriptions are maintained
independently per (S,G) -- (S1,G1) and (S2,G2) are routed
independently, even if G1 and G2 are the same.  This has nothing to do
with topology -- it's a property of the service model.  Shared trees
are not used by SSM.

> in scalability in building multicast trees??

Not from any effect of making protocol changes to PIM-SM.  The same
mechanisms are used.  SSM applies most naturally to broadcast-like
sessions where there is a single natural source anyway, and there is
no scalability impact for those sessions.  If anything, the protocol
costs go down a little bit for those apps because the overhead of
going to the shared tree is eliminated.

> 3- is the source address should be in teh range 232/8 also or it is just

No.  Source addresses for SSM are normal IP host addresses.

-Hugh