RE: LMP Question: fault management messages

["Sameh M. Elsharkawy" <selsharkawy@fwion.com>]

I fully agree with this comment since the removal of ChannelFailNack message
from the fault management procedure prevent downstream nodes from localizing
the failure on their input ports. If signaling is responsible for
propagating the information, this will delay the recovery process, until the
information   is disseminated by signaling.

Thanks

Sameh M. Elsharkawy
Senior Member of Technical Staff
FirstWave Intelligent Optical Networks
6301 Ivy Lane, Suite 700, Greenbelt, MD 20770
(301) 345-2137 x1034



-----Original Message-----
From: George Young [mailto:george.young@edgeflow.com]
Sent: Tuesday, October 09, 2001 1:57 PM
To: ccamp@ops.ietf.org
Subject: LMP Question: fault management messages


I've reviewed draft-ietf-ccamp-lmp-01.txt and the new ChannelStatus
message and its friends.

In Section 6.2. Fault Localization Procedure, LMP states "Once the
failure has been localized, the signaling protocols can be used to
initiate span or path protection/restoration procedures". This is
workable and signalling can reroute around the link or the path,
releasing resources as appropriate. However, with the departure of the
ChannelFailNack, the node at the receive end of the faulty link does not
find out about the fault from either the signalling protocol or LMP. As
bidirectional paths are allocated, there is a chance that the failed
link will be allocated to a subsequent call through this node.

Furthermore, assuming a signalling protocol has established paths, and
indicated their active or backup status with the Administrative Status
object in GMPLS, there does not appear to be any need in LMP for the
Active/Deactive indications in the CHANNEL_STATUS object. This
information has already been conveyed by the signalling protocol during
path establishment.  

If my understanding is correct, ChannelFailNack functionality is needed
and the Active and Deactive values of the CHANNEL_STATUS object are not.

Regards,
George R. Young
edgeflow Inc.
329 March Rd., Kanata, ON, Canada, K2K 2E1
phone: +1 613-270-9279 Ext 287
fax: +1 613-270-9268