LMP: Suppression of Downstream Alarms...

[Carmine Daloia <daloia@lucent.com>]

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