RE: Suppression of Downstream Alarms...

[neil.2.harrison@bt.com]

Absolutely right Malcolm....and that's also why you will see the function
FDI (Forward Defect Indicator) proposed for MPLS OAM also in the user-plane.
This basic and important principle (ie suppression of downstream and client
layer alarms) is well understood by operators and most manufacturers.

I am glad to see that (in Jonathan's response to Carmine's mail) this
principle is recognised and agreed with. 

regards, Neil

> -----Original Message-----
> From: Malcolm Betts [mailto:betts01@nortelnetworks.com]
> Sent: 20 November 2001 21:04
> To: 'Carmine Daloia'; ccamp@ops.ietf.org
> Cc: tsg15q11@itu.int; t1x15@t1.org
> Subject: 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
> 
>