[c-nsp] m-vpn

[Mark Tinka]

On Tuesday, May 29, 2012 06:23:45 PM Phil Mayers wrote:

> No. SSM *is* sparse-mode. It's just sparse mode without
> *,g joins.

In NG-MVPN (or BGP-MVPN, as Juniper call it nowadays), you 
can deploy an MVPN tree as either SPT-only, or RPT-SPT, when 
running PIM-SM.

In NG-MVPN, BGP replaces PIM for all PIM functionality 
(hence the lack of PIM in the core network).

RPT-SPT is akin to regular PIM in a PIM-based core, where an 
IGMP client tries to join a Multicast group, and (*,G) is 
initiated to toward the RP.

However, SPT-only means that while an RP configuration may 
exist in the Receiver PE router, when the Receiver PE router 
receives a (*,G) join request, it searches for and consults 
what is know as a Source Active (SA) route in its routing 
table (SA routes are Type 5 BGP routes in NG-MVPN's). If it 
finds a matching one, it automatically converts the join 
message to a Type 6 Multicast route, which is the same as 
(S,G), and the appropriate route is installed in the router. 
In SPT-only mode, single forwarder election, rather than the 
RP, is used to determine the source of the Multicast 
traffic.

Pretty cool.

You can read all about it here:

	http://tools.ietf.org/html/rfc6514#section-14

Mark.