Subject: RE: [Mter] Any news?

From: "Diego Caviglia" <[email-masked]>
Date: Wed, 15 Mar 2006 12:28:16 +0100

Hi Jean-Louis,
               actually I'm interested in interworking between data plane
protection and control plane recovery mechanism.

My major concern on that issue is the interworking between the MS-SPRing
and GMPLS recovery.

Section 5.3.1 states that:
  "Note that some data plane recovery mechanisms such as the SONET/SDH
   protection mechanism may co-exist with GMPLS P&R mechanisms. The co-
   existence with data plane recovery and GMPLS recovery mechanisms is
   not addressed in this section."

Moreover
"7. Future items

   Here is a non exhaustive set of additional items that need to be
   covered as part of the MTER work:
    - Other combinations of recovery techniques (e.g. BGP-IGP
      interactions, IGP-IPFRR interactions, etc.);
    - Superset of elementary combinations (e.g IGP Fast Convergence for
      node data plane failures + Graceful Restart for node control plane
      failures + MPLS FRR link protection for link failures).
   -  Combination of recovery techniques to protect distinct traffics
      (e.g. IGP Fast convergence and end-to-end MPLS-TE recovery); "

Is the interworking between 'data palane' protection scheme and GMPLS
recovery mechanism in the scope of MTER?

My vote on that question is yes, that issue needs to be addressed.

Huub Dino and myself have written a requirement ID about the interworking
between MS-SPRing and GMPLS
(http://www1.ietf.org/internet-drafts/draft-caviglia-ccamp-gmpls-msspring-req-00.txt),
 is that work in the scope of MTER?  My last impression was that was in the
scope, is that impression correct?

Section 6.1 quotes AIS as possible mechanism to detect failures.

Is the following possible issue in the scope of MTER (actually is a
partitioning problem rather that a layer problem)

a<--------->b<--------->c<------->D<--------->E<---------->F<---------->G<-------->h<---------->i<-------->z

Caps letters indicates GMPLS capable nodes while the low caps are legacy
SDH/SONET nodes.

One can say that D, E, F, G is the backbone network while a, b, c and h, i,
z are two access network.

A network operator wants to set up a trail fom a to z, we can see that
trail made by three pieces:
1)    a<----->D
2)    D<----->G
3)    G<----->z

Pieces 1 and 3 are set-up via NMS and are not under the control of the
GMPLS while piece 2 is an e2e restored circuit.

If the AIS is used as trigger for the GMPLS restoration a failure in either
piece 1 or 2 (that injects AIS along all the trail) can trigger the e2e
GMPLS recovery scheme.  Given that the failure is not recoverable inside
the piece 2, the risk is that restoration never ends.

Regards

Diego

"LE ROUX Jean-Louis RD-CORE-LAN" <[email-masked]> on
15/03/2006 11.45.00

To:    "Diego Caviglia" <[email-masked]>, <[email-masked]>
cc:

Subject:    RE: [Mter] Any news?

Hi Diego,

We are actually waiting for comments on the problem statement,
so feel free to comment!

Regards,

JL

> -----Message d'origine-----
> De : Diego Caviglia [mailto:[email-masked]]
> Envoyé : mercredi 15 mars 2006 11:37
> À : [email-masked]
> Objet : [Mter] Any news?
>
> Hi all,
>              any news on the MTER activity?
>
> Regards
>
> Diego
>
> PS are there any ID apart the problem statement?
>
>
>
> _______________________________________________
> MTER mailing list
> [email-masked]
> https://www1.ietf.org/mailman/listinfo/mter
>

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---

From: Didier Colle <[email-masked]>
Date: Wed, 15 Mar 2006 13:51:02 +0100

Dear Diego,

[CUT]

>the piece 2, the risk is that restoration never ends.
You are right this is an issue. However, I believe the typical solution 
to overcome this problem is establishing a tandem connection in each of 
the three segments and making use of the sublayer supervision function 
in order to allow detecting whether the failure occured ON or UPSTREAM 
OF the tandem connection.
For example: when a failure occurs in segment 1 (thus a<---->D) then D 
will translate the the AU_AIS into a IncAIS (N-bytes in the path 
overhead of the tandem connection D->G). G will detect this IncAIS and 
will simply generate AIS downstream. However, when segment 2 fails (thus 
D<--->G), then G may receive an AU_AIS (and not a IncAIS) implying that 
it has to trigger the GMPLS P&R.

Kind regards,

Didier

[CUT]

-- 
Didier Colle
Ghent University - IMEC - IBBT
Department of Information Technology (INTEC)
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Email: [email-masked]
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