Re: [mpls] RtgDir review: draft-ietf-mpls-tp-rosetta-stone-12.txt

[Huub van Helvoort <[e-mail]>]

Hello Manav,

You wrote:

> I have been selected as the Routing Directorate reviewer for this draft.

Thank you for your review.

I will address all your comments in the next spin of the draft.

I only want to bring some clarification to your proposal:

> o) In 3.7, it would be useful to mention that an important
 > property of co-routed bidirectional path is that the forward
 > and backward directions share fate.
 > Similarly, in 3.1, we should mention that the forward and
 > backward directions don't share fate.


Fate-sharing is NOT a requirement for co-routed bi-directional
paths.  It is only a secondary effect.
E.g. in a cable only one of the fibers can fail/break, same for internal 
ports in routers, as well as forwarding.

The main requirements for co-routed bidirectional paths are:
== follow exactly the same path i.e. physical sections, and
    nodes in both directions
== the MEPS at the end-points can communicate directly via
    the RI (remote interface) NOT via the management plane
== during a protection switch both directions are switched
    (at the same time) from working entity to protection entity.
== both are managed as a single entity

The only fate-sharing requirement in ITU-T is for OAM packets
and data packets transported between the same endpoints
See the first paragraph in clauses 6.4 and 7.1 of G.8113.1
and G.8113.2.

To resolve your point I can add text to 3.7 that both directions
are managed and operated as a single entity;
and in 3.1 that they need not be a single management and
operational entity.


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