Subject: Multiple PIM instances for mvpn

From: "Arut Selvan" <[email-masked]>
Date: Wed, 11 May 2005 09:39:33 -0500

Hi,

I came across "VPN-specific PIM instances" being mentioned in section 2.1 of

draft-rosen-vpn-mcast-08.txt. I wonder why multiple instances of PIM would

be required. Can't we have a single PIM instance managing multiple MVRFs?

I have come across an implementation which has a single instance of routing protocols

in the case of unicast. Why is it different for multicast ?

Thanks,

Arut

2.1. Multicast VRFs

Each VRF has its own multicast routing table.  When a multicast data
or control packet is received from a particular CE device, multicast
routing is done in the associated VRF.

Each PE router runs a number of instances of PIM-SM, as many as one
per VRF.  In each instance of PIM-SM, the PE maintains a PIM
adjacency with each of the PIM-capable CE routers associated with
that VRF.  The multicast routing table created by each instance is
specific to the corresponding VRF.  We will refer to these PIM
instances as "VPN-specific PIM instances".

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From: Yiqun Cai <[email-masked]>
Date: Wed, 11 May 2005 18:49:59 -0700 (PDT)

> in the case of unicast. Why is it different for multicast ?

"A VPN-specific PIM instance" refers to the PIM protocol machinery
executed in the context of that VPN/VRF on the PE router.  It doesn't
imply or mandate how one should implement it, especially how many OS
specific processes or taskes that should be created.

-- 
Yiqun