Re: [mpls] applicability of draft-wijnands-mpls-mldp-in-band-signaling-02

[Eric Rosen <erosen at cisco.com>]

Yakov> What I showed in my example above is a fairly simple PIM-SM in ASM
Yakov> mode scenario.  Since as you said above, supporting this scenario "is
Yakov> out of scope", the draft has to say that supporting PIM-SM in ASM
Yakov> mode is "out of scope".

That doesn't follow.  Supporting PIM-SM in ASM mode does require that there
be a way to discover the active sources, but joining a shared tree is not
the only way to do that.

It is fair to ask the draft to say something like the following:

      "When PIM-SM is used in ASM mode, the usual means of discovering
      active sources is to join a sparse mode shared tree.  However, this
      document does not provide any method of transporting a sparse mode
      shared tree across an MPLS network.  To apply the technique of this
      document to PIM-SM in ASM mode, there must be some other means of
      discovering the active sources.  One possible means is the use of
      MSDP, but specification of such means is outside the scope of this
      document".

Yakov> the draft needs to explicitly spell out how exactly MSDP will be used
Yakov> in the scenarios like the one I showed above.

Well, then it wouldn't be out of scope, would it?

The notion of discovering the active sources without using a shared tree
isn't exactly new; see, e.g., section 14 of draft-ietf-l3vpn-2547bis-mcast-
bgp.