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RE: Suppression of Downstream Alarms...
Carmine, I agree, the suppression of down stream alarms (AIS) should be
provided by the transport equipment and should not rely on the use of a
signalling protocol. Since as you indicated not all of the network elements
on the links between the OXCs (e.g. Amplifiers) will have access to the
signalling network.
Malcolm Betts
Advanced Network Technology
Nortel Networks
Phone: +1 613 763 7860 (ESN 393)
FAX: +1 613 763 6608 (ESN 393)
email: betts01@nortelnetworks.com
-----Original Message-----
From: Carmine Daloia [mailto:daloia@lucent.com]
Sent: Monday, 19 November, 2001 09:44
To: ccamp@ops.ietf.org
Cc: tsg15q11@itu.int; t1x15@t1.org
Subject: LMP: Suppression of Downstream Alarms...
Hi all,
As I read through Section 6 "Fault Management", one issue that it seems
to be addressing is "Suppression of Downstream Alarms".
In section 6.2, it states that "If data links fail between two PXCs, the
power monitoring system in all of the downstream nodes may detect LOL
and indicate a failure. To avoid multiple alarms stemming from the same
failure, LMP provides a failure notification through the ChannelStatus
message...".
I agree that the suppression of downstream alarms is an important issue.
If we look at standard networks (both SONET/SDH and OTN), this
capability is already provided by the overhead in SDH/SONET and G.709
OTN. G.709 OTN handles suppression of alarms in both all-optical
networks as well as opaque networks. I don't think we need to burden the
control plane with such functions when the transport plane handles this
in standard networks. In fact the transport plane handles suppression of
alarms on all equipment in the network (not just cross-connects).
If we look at a pre-OTN ("non-standard") scenario consisting of
Cross-connects, Optical Line Systems, and Optical Amplifiers supporting
a DWDM networked solution, we can analyze two scenarios. One scenario is
an opaque network (e.g., the OLS supports 3R). In this scenario, the
downstream Cross-connects would not detect LOL upon faults occurring
upstream. The 3R points on the OLS Line Systems would insert some type
of signal downstream. Therefore the mechanism described in Section 6.2
does not apply. Another scenario is an all-optical pre-OTN network. Note
that other equipment besides Cross-connects (e.g., Optical Amplifiers)
in an all-optical network may alarm due to upstream faults. These alarms
also need to be suppressed. LMP seems to only address the suppression of
downstream alarms on cross-connects without taking into consideration
the network that sits between the cross-connects. Is LMP also expected
to have to be processed on Optical Amplifiers? This seems to be
undesirable, especially given all the various applications that seem to
be included into the LMP protocol that would not have anything to do
with Optical Amplifieris.
Any other views?
Carmine