[Mter] THREAD 2 - Combining IGP Fast Covnergence and Graceful Restart

"LE ROUX Jean-Louis RD-CORE-LAN" <jeanlouis.leroux@francetelecom.com> Wed, 17 May 2006 13:50 UTC

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From: LE ROUX Jean-Louis RD-CORE-LAN <jeanlouis.leroux@francetelecom.com>
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Subject: [Mter] THREAD 2 - Combining IGP Fast Covnergence and Graceful Restart
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Hi folks,
Let's start discussion on scenario 2 = Combining IGP Fast Convergence
and IGP Graceful Restart
(section 5.2 of draft-ahmad-mter-problem-statement-00.txt)
Comments on this scenario are required.
In particluar your feedback on these two points would be really useful:
-Is there a need for a mechanism that would allow to rapidly make a
clear distinction between control plane failures and data plane
Such mechanism may be considered to efficiently handle this MTER
-Is there a need for a MIB allowing to monitor such interaction:
     -e.g. record cases where a GR procedure has failed, leading to
increasing convergence time of the IGP
     -Monitor GR performances in order to be able to tune more
aggressively IGP timers 
JL, JP and Raymond.


		From: JP Vasseur <jvasseur@cisco.com>
		Date: May 15, 2006 1:09:02 PM EDT
		To: mter@ietf.org
		Cc: raymond_zhang@bt.infonet.com
		Subject: [Mter] Need to decide on potential next steps
for MTER

		Below the email we sent to the list some time ago,
seeking for feed-backs but so far the list has been pretty quiet. During
the past few months we received a very few off-line positive feed-backs
indicating some interest in this work. It is now a good time to decide
on whether there is enough interest to work on this topic by the IETF
community in which case we will request a BOF approval or whether the
interest is too weak to pursue this work.
		So we will follow up with a few discussion threads
related to the scenarios described in the problem statement ID, for
which we'd like to get your feed-back relatively quickly, should you
think that it is worth being pursed.
		JP, Jean-Louis and Raymond.

		It took a little while to come up with a clear problem
statement but we now have an I-D
mter-problem-statement-00.txt (thanks to the authors)) that will
hopefully trigger some discussion with the objective to see whether
there is enough interest to pursue this work at the IETF.

		The draft has been structured so as to first show three
scenarios where various recovery mechanisms could be used in
combination. This does not aim to cover all possible cases but some
pretty common deployment scenario for the sake of illustration. Then
various Multi- TEchnology Recovery (MTER) issues are discussed.

		What is the objective of this work ?

		Let's start with the set of non-objective first ...
		* There is no intention to come up with protocols
extensions that are being worked out in existing WGs (ISIS, IDR, CCAMP,
		* Discuss implementation-specific issues

		Now the objectives ...

		What has been shown through the three MTER deployment
cases making use of multiple recovery mechanisms in combination is the

		-> There are cases where being able to identify the root
failure cause would significantly improve various recovery metrics such
as the convergence time, required backup capacity, ... and so on. Do we
need to work on such mechanisms at the IETF is an open question ?

		-> MIBs and OAM tools have been defined for most of the
recovery techniques (IGP, BGP, MPLS FRR, GMPLS, ... ) and there are
clearly no such tool for the aspects related to their combined use. It
looks like the availability of such tools would help Service Providers
to manage, tune and troubleshooting their network. Again, feed-backs
from this ML are critical to see how to move forward and if the
community expressed some interest.

		Thanks for your feed-backs.

		JP, Jean-Louis and Raymond.

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