Re: Multicast in BGP/MPLS VPN with pseudo wires technology

[Eric Rosen <erosen at cisco.com>]

> In the context of my draft, the pseudowires concept only means a
> bidirectional virtual circuit used as a MVRF related virtual interface. 

I don't think it needs to be  bidirectional, unless we are also using it for
sending control messages.

> RPF checking is a very important mechanism for multicast processing. 

Sometimes in multicast  processing, when you receive a  data packet you need
to figure out the tree on which the packet is traveling.  When the packet is
an IP  packet, all  the information  you have is  the <S,  G> and  the input
interface.  The  packet carries  no identifier  of the tree  on which  it is
traveling, this  must be inferred from  the <S,G> and the  in put interface.
However, when the packet is an MPLS packet, it may be carrying a label which
identifies  a particular  tree, rather  than just  identifying  a particular
<S,G>.  In  that case,  you would not  need to  know the input  interface in
order to figure out the tree  on which the packet is traveling.  Therefore I
am not really sure we will need this "virtual interface" concept.

I think we will need to pin  down the details of the control plane(s) before
we can fully evaluate this issue.