Subject: [mpls] progressing draft-mtaillon-mpls-summary-frr-rsvpte

From: Loa Andersson <[email-masked]>
Date: Thu, 17 Sep 2015 12:44:36 +0200

Working Groups,

The mpls and teas working group chairs discussed the home working
group for draft-mtaillon-mpls-summary-frr-rsvpte. Since the is entirely
the choice fell on the mpls working group. We also decided to keep
the teas wg in the loop.

We have just initiated the mpls review team (MPLS-RT) review if this
draft. This review is focused on if we want to accept the document as
a working group draft, and if it is in shape for us to do so.

The MPLS-RT reviewers are picked by the mpls chair that will shepherd
the document.

This also mean that this is a good time for anyone, from both working
groups, to review the document. Please send your reviews to the mpls
working group mailing list ([email-masked]).

/Loa

-- 

Loa Andersson                        email: [email-masked]
Senior MPLS Expert                          [email-masked]
Huawei Technologies (consultant)     phone: +46 739 81 21 64

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From: Lou Berger <[email-masked]>
Date: Thu, 17 Sep 2015 11:21:10 -0400

I have some comments on the proposed mechanism (I have no opinion on
utility or likely implementation):

1. WRT SUMMARY_FRR_BYPASS_ACTIVE object

RSVP object space is a pretty scarce resource and it seems we have a
number of existing objects that could be reused to support transport of
the required information.  Some candidates include: the Association
object with a new association type; or perhaps the PRIMARY_PATH_ROUTE
Object with a new C-type.

2. SUMMARY_FRR_BYPASS_ASSIGNMENT subobjects

While RFC4090 makes use of RRO carried information, it does so without
changing the RRO format.  (At the time, I recall some used this as
justification for RRO usage vs introducing new formats.)  The new SOs
introduce new information and don't seem to be particularly linked to
normal RRO operation -- and more significantly really defining new
transit-node to transit-node signaling semantics:

   The PLR notifies the MP of the bypass tunnel assignment via adding a
   SUMMARY_FRR_BYPASS_ASSIGNMENT subobject to the RSVP Path message
   RECORD_ROUTE object ...

   The MP acknowledges the PLR's assignment by signalling a
   SUMMARY_FRR_BYPASS_ASSIGNMENT subobject within the RSVP Resv messsage
   RECORD_ROUTE object.

IMO this usage of RRO is really wrong (and is easily broken by
application of RRO policies).  I think extending an existing object
class is a better approach. Extending one of the existing FRR objects
would probably be cleanest, but think the authors should consider and
propose their preference.

Lou

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From: "Tarek Saad (tsaad)" <[email-masked]>
Date: Mon, 21 Sep 2015 02:39:11 +0000

Thanks Lou for your review and comments. Inline for responses.

>Object with a new C-type.
[TS]: seems reasonable, we will discuss this among the authors for a
suitable extension.

>transit-node to transit-node signaling semantics:
[TS]: the new SO, is recording local information that if intercepted by
another LSR (PLR or MP that understands it) can use it for further summary
FRR processing. This resembles to an extent what other RRO SOs do today
(e.g. node-id and label Sos) for regular FRR.

>application of RRO policies).  I think extending an existing object
[TS]: yes, the comment (about RRO policies) is rightfully correct. .. but
also applicable to existing RRO/SO(s) (e.g. node-id and/or label SO)
needed for proper FRR too. That said, will discuss extension of an
existing (FRR) object amongst the authors for (dis)advantages.

Regards,
Tarek

>_______________________________________________
>mpls mailing list
>[email-masked]
>https://www.ietf.org/mailman/listinfo/mpls

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From: Lou Berger <[email-masked]>
Date: Fri, 25 Sep 2015 08:20:16 -0400

Tarek,
    Thanks for the response, see below.

> [TS]: seems reasonable, we will discuss this among the authors for a
great.

> (e.g. node-id and label Sos) for regular FRR.

The point was that those SOs serve their original purpose of being
useful in constructing EROs, while the new SOs really have entirely
different semantics -- for example what does it mean if an ingress
includes the new SOs for a transit node?

> needed for proper FRR too. 
Again, this was leveraging SOs that were defined & used for other
purposes and overloading their semantics.

> That said, will discuss extension of an

That would be great and will be very interested in hearing your thoughts.

Thanks,
Lou