RE: multicast senders behind an IGMP Proxy

Hi,

I would like to suggest following methods to  resolve this
issue:

- TTL scoping can be used to control the distribution of
multicast traffic with the objective of easing stress on
scarce resources viz. bandwidth.

- Another way (and probably a preferred choice) would be to
use administratively scoped IP multicast [rfc2365]. 

Moreover, these methods can (to a certain extent) help in
achieving privacy.

PS: "sending audio to all of your IP-enabled speakers
distributed throughout your house" seems to be very
ambitious usage of multicast :-) 

Regards,
Prashant Jhingran

Huawei Technologies
+91-80-41117676 Ext -7175
+91-9448927814

"Sing, dance, serve, meditate and celebrate" 
 - www.artofliving.org  

-----Original Message-----
From: Dan Wing [mailto:[email protected]] 
Sent: Friday, June 22, 2007 5:48 AM
To: [email protected]; [email protected]
Cc: Toerless Eckert
Subject: [magma] multicast senders behind an IGMP Proxy

During WGLC, there was clear consensus from MAGMA and MBONED
that supporting
multicast senders behind the IGMP Proxy device was
desirable.  However,
while wrapping up draft-ietf-behave-multicast-07, Toerless
pointed out a
problem with multicast senders behind an IGMP Proxy device
(any IGMP Proxy
device -- not just an IGMP Proxy in a NAT).

The problem is that any multicast flows generated behind the
IGMP proxy will
be forwarded up the access link towards the Internet -- even
for flows that
you want to keep within your network.  Concrete examples of
generating
multicast within a home network include:

 * sending audio to all of your IP-enabled speakers
distributed 
   throughout your house,  
 * IP-enabled intercom system, 
 * HD video to multiple telvision sets (kitchen and living
room).

In each case, you "could" do unicast, but especially for HD
one might easily
envision not having sufficient bandwidth or not wanting to
waste the
bandwidth (which might be used for other things).

Does anyone have suggestions on how this might be resolved?

-d


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