Subject: Re: WG Last Call for draft-ietf-l3vpn-mvpn-bidir

From: Eric Rosen <[email-masked]>
Date: Mon, 05 May 2014 11:51:17 -0400

Jeffrey, thanks for your comments.

> There are the following two paragraphs in their respective sections:

   When the Flat Partitioned Method is used to implement the
   "Partitioned Sets of PEs" method of supporting C-BIDIR, as discussed
   in section 11.2 of [MVPN] and section 3.6 of [RFC6517], a C-BIDIR
   flow MUST be carried only on an I-PMSI or on a (C-*,C-G-BIDIR),
   (C-*,C-*-BIDIR), or (C-*,C-*) S-PMSI.  A PE MUST NOT originate any
   (C-S,C-G-BIDIR) S-PMSI A-D routes. (Though it may of course originate
   (C-S,C-G) S-PMSI A-D routes for C-G's that are not C-BIDIR groups.)
   Packets of a C-BIDIR flow MUST NOT be carried on a (C-S,C-*) S-PMSI.

   ...

   When the Hierarchical Partitioned Method is used to implement the
   "Partitioned Sets of PEs" method of supporting C-BIDIR, as discussed
   in section 11.2 of [MVPN] and section 3.6 of [RFC6517], a C-BIDIR
   flow MUST be carried only on an I-PMSI or on a (C-*,C-G-BIDIR),
   (C-*,C-*-BIDIR), or (C-*,C-*) S-PMSI.  A PE MUST NOT originate any
   (C-S,C-G-BIDIR) S-PMSI A-D routes. (Though it may of course originate
   (C-S,C-G) S-PMSI A-D routes for C-G's that are not C-BIDIR groups.)
   Packets of a C-BIDIR flow MUST NOT be carried on a (C-S,C-*) S-PMSI.

> Clearly, there is no difference between hierarchical partition and flat
> partition in this regard.

How about if I remove these paragraphs from section 3.2.1 and 3.2.2
respectively, and add a single paragraph at the front of section 3.2 that
begins "When either the Flat or the Hierarchical Partitioned method is used
..."

> The following does not seem to be correct in 3.2.2:

   As in [MVPN] and [MVPN-BGP], an S-PMSI A-D route does not need to be
   originated by a particular PE, say PE1, until PE1 has received a
   "join" indicating that some other PE is interested in receiving a
   C-flow whose C-S or C-RP(A) is reachable from PE1 via a VRF
   interface.

> For example, if the S-PMSI is used to carry unidirectional traffic from
> PE2 (not PE1), or to carry bidirectional traffic on sender-only branches?

I will remove this paragraph.

> For the following in 3.2.2.2:

   Note that the PE Distinguisher Label to be used is the one assigned
   by the root of the P-tunnel to the address of PE2, not the one
   assigned to the address of PE1.  Note also that the root of the
   P-tunnel might be a PE other than PE1 or PE2.

> It is for bidirectional flows. For unidirectional flows, the label
> assigned by the root for PE1 need to be used.

Two paragraphs before the paragraph you cite it says "the remainder of this
section applies only to C\-BIDIR flows".  So your point is correct, but so
is the draft ;-)

> 3.2.2.3. When an I-PMSI is a 'Match for Transmission'

   ...

   If the C-flow is a BIDIR-PIM C-flow with group address C-G-BIDIR, the
   rules as applied by PE1 are the same as those given in section
   3.2.1.2.

> 3.2.1.2 does not talk about labels. We should add some text here about labels.

I think it is sufficient to add:

   "Note that if a matching I-PMSI A-D route is found, the PTA of that route
   will have a non-zero MPLS label.  This label must be pushed on each
   packet of the C-flow before that packet is transmitted through the
   P-tunnel identified in the PTA."

---

From: "Jeffrey (Zhaohui) Zhang" <[email-masked]>
Date: Mon, 5 May 2014 16:23:50 +0000

Eric,

> begins "When either the Flat or the Hierarchical Partitioned method is used

Even with unpartitioned method?

> section applies only to C\-BIDIR flows".  So your point is correct, but so

But shouldn't we also talk about unidirectional flows, since it is not covered in 6625? 3.2.2.3 does cover that.

Jeffrey