Re: Suppression of Downstream Alarms...

[Germano Gasparini <germano.gasparini@alcatel.it>]

Hello everybody

This is my first intervention on this exploder, so a brief self-introduction.
My name is Germano Gasparini. Currently I'm an Alcatel Italia employee in
the Network Management System and Architecture team for transport
network (SDH/WDM).

My personal position on the subject is that there is no need to duplicate on
the signalling alarm suppression indications (such as AIS and FDI) already
provided by the transport plane. Normally AIS and FDI are processed by the
transport hardware logic and therefore they are supposedly faster than
a corresponding processing in the signalling layer - thus making redundant
having the same information carried over there.

Best regards
Germano Gasparini

neil.2.harrison@bt.com wrote:

> 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
> >
> >

--
Germano Gasparini - A-Optics Network Management Systems
==========================================================
Phone: 2-210.(3)4910    Fax: 2-210.(3)4185
Please reply at: mailto:germano.gasparini@alcatel.it