Subject: Re: [mpls] Regarding draft-wijnands-mpls-mldp-csc-02.txt

From: Eric Rosen <[email-masked]>
Date: Wed, 02 Dec 2009 10:18:00 -0500

> The MVPN solution that L3VPN WG has to produce is based on the
> requirements developed in L3VPN WG, as specified in rfc4834, and
> *not* on what you think "will be a quite common deployment
> scenario"

There is no reason why the WG should not consider simplifications that
optimize for particular deployment scenarios, particularly if those
scenarios are common.

> supporting carrier that "does not want to deploy BGP C-multicast routing",
> which you use as a justification for the approach specified in
> draft-wijnands-mpls-mldp-csc, is *not* one of the requirements listed in
> that rfc.

I don't think that anything in the requirements doc prevents the WG from
considering design goals that or simplifications that are not explicitly
mentioned there.  If SPs are interested in such simplifications, then there
should be public, interoperable standard for them.

Also, it's made quite clear in the drafts that the WG has already approved
that BGP C-multicast routing is optional to deploy.  I don't know if anyone
will ever deploy it or not, but I'm pretty sure that an SP that does not
deploy it for signaling customer multicast routes is not going to deploy it
just to provide unaggregated CsC mLDP-in-mLDP service!  Not when there's a
much simpler solution available.

> as John pointed out in his e-mail, the approach specified in
> draft-wijnands-mpls-mldp-csc does *not* meet two of the "SHOULD"
> requirements specified in rfc4834.

There's no reason why every individual option should meet each requirement.
And there's no reason for a service provider to deploy something that is
more complex than needed in that provider's environment.  

If we were required to design a set of eating utensils that supported the
eating of both liquid and solid foods, I think it would be okay to design a
spoon and a fork; we would not have to design a swiss army knife.  And I
don't think anyone would object to the inclusion of the "fork option" on the
grounds that you can't eat soup with a fork.

---

From: Yakov Rekhter <[email-masked]>
Date: Tue, 8 Dec 2009 11:03:06 -0800

Eric,

> optimize for particular deployment scenarios, particularly if those

Then please bring this up in L3VPN WG mailing list, as the topic
of the discussion is MVPN (and as such it is outside the scope
of MPLS WG).

Yakov.