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Re: IPTV and ASM
From: Mark Tinka <mtinka () globaltransit net>
Date: Thu, 29 Dec 2011 18:03:20 +0800

On Thursday, December 29, 2011 08:02:04 AM Keegan Holley 

Isn't source discovery and efficiency a big concern for
ASM?  If individual streams are tied to a specific
source then it's possible to live without some of the
overhead involved in ASM.  Joins go straight to the
source, traffic is disseminated via direct paths instead
of being replicated by the RP, etc etc..

In our case, Source discovery happens once, and BGP updates 
containing that information is sent to all Receiver PE 
routers in the MVPN.

They then generate Type 7 routes locally (due to running 
SPT-only mode), which are essentially (S,G) routes.

Once a customer sends a Join message to subscribe to a 
group, the Receiver PE router just serves it locally. No 
need to send any requests back to the RP.

This breaks regular PIM mechanisms, but is a welcome 
deviation that makes a lot of sense.

One does have the option of running RPT-SPT modes which are 
akin to regular IP Multicast.


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