Re: [PWE3] draft-medved-pwe3-of-config-00.txt posted, review please

[David Meyer <[e-mail]>]

Alexander,


On Tue, Jul 3, 2012 at 10:05 PM, Alexander Vainshtein
<[e-mail]> wrote:
> Andy and all,
>
> I've looked up the draft in question, and I have some comments/questions in
> addition to Andy's:
>
> The PWE3 WG has defined multiple MIBs that can be used for PW setup and
> teardown by a      management application (MPLS-TP or not). IMO the draft
> should indicate that the method proposed there is an alternative not just to
> PW signaling via T-LDP (as Andy has said) but also to static PW setup using
> these MIBs.

As I mentioned, the draft did not intended to provide an alternate
control plane; hopefully that will be clear in the next rev. I'll add
some text around the point you make WRT MIBs above.

> The wording of the draft seems to suggest a difference between the head-end
> PE and the tail-end one, e.g., as in he following fragment: "Although the
> Virtual OF switch is the same a both the head-end and tail-end nodes, the
> group table is only used at the head-end node, where a Fast Failover group
> is set up for each pair of ports that correspond to the primary-backup
> Transport LSP pair.  At the tail-end node, only flows are set up." I do not
> understand how does this (and similar) fragments deal with the fact of PWs
> being inherently bidirectional.

I've cleaned this up. The distinction was in the description, not the
functionality.  Thanks for point this out.

> The PWs run in MPLS (or MPLS-TP) tunnels in order to improve scalability of
> P routers, because the same tunnel between a given pair of PEs can be shared
> by multiple PW instances. It is not clear from the text how such sharing can
> be accommodated in the proposed OF switch model.

Humm, here is nothing that stops the "transport virtual port" from
sharing transport labels if that is appropriate. Perhaps I'm not
understanding your point?

>  Reference to RFC 6423 suggests that OAM discussion in the draft is PW OAM
> and OAM for Tunnel LSPs. Does this imply that the protection actions are
> triggered by the PW-level OAM, and, what is supposed to happen if a pair of
> T-LSPs is shared by multiple PW instances?

That wasn't the intention; will clean up the text.

> The text defining the OF switch and its matching rules is not clear. In
> particular, it seems to imply that PW labels are checked from being received
> from a specific T-LSP (as a port of the OF switch). IMHO this a clear
> contradiction to the MPLS (and MPLS-TP) data plane as defined in RFC 3031,
> and to the fact that PW labels are allocated from the per-platform label
> space (as per RFC 4447).

Again, this wasn't the intention. I'll have a look at how we might
clean this up.

Thanks for the comments.


--dmm