Re: Suppression of Downstream Alarms...

[Dimitri Papadimitriou <[e-mail]>]

Hi Sudheer,

Of course, the scope is broader than strictly G.709
based XC, and supportive equipment. This is why we
can really benefit from the generic definition of this
promising protocol while customizing it for specific
technologies like SDH/Sonet, etc. that supports "in-band"
it would be more accurate to say "transport plane" defect
indication.

Cheers,
- dimitri.

Sudheer Dharanikota wrote:
> 
> Hi Carmine:
> 
> Couple of observations...
> 
> It seems you are assuming only G.709 based cross connects
> only.
> Please let me know if I am not correct.
> 
> LMP-DWDM works for PXC and other crossconencts which does
> not
> use inband fault notification.
> 
> Cheers,
> 
> sudheer
> 
> Carmine Daloia wrote:
> 
> > Jonathan,
> >
> > The LMP-WDM document specifies the signaling between the
> > Cross-connect and OLS, assuming they are from different
> > vendors. If they are from different vendors, then a
> > standard interface is needed to exchange some information.
> > One type of information that would need to be exchanged is
> > some OAM signals. Maarten described some of these signals
> > in his VBI document. However, I don't see why OAM signals
> > would have to be exchanged directly between the
> > cross-connects themselves via LMP.
> >
> > Let's look at the following network.
> >
> > OXC1 --- OLSA --- OXC2 --- OLSB --- OXC3 --- OLSC --- OXC4
> >
> > Note that the OLS consists of DWDM Mux/Dmux Terminals and
> > Optical Amplifiers.
> >
> > Let's assume a failure on OLSA. OLSA via overhead within
> > an OSC suppresses alarms within OLSA. OAM messages (e.g.,
> > Optical Channel FDI) could be carried over the LMP-WDM
> > control channel to OXC2. OXC2 will have to forward the FDI
> > signals downstream over the LMP-WDM control channel to
> > OLSB. OLSB will then forward these FDI signals over its
> > OSC and then over the LMP-WDM control channel to OXC3.....
> > etc...
> >
> > Note that OXC2 does not need to directly forward these FDI
> > signals to OXC3. So it is possible, that in LMP-WDM, we
> > may need to define messages corresponding to FDI signals
> > to suppress downstream alarms, however we don't need to
> > define such messages in LMP.
> >
> > Thanks
> > Carmine
> >
> > Jonathan Lang wrote:
> >
> >> Carmine,
> >>   Please see inline.
> >>
> >> Thanks,
> >> Jonathan
> >>
> >>
> >> > -----Original Message-----
> >> > From: Carmine Daloia [mailto:[e-mail]]
> >> > Sent: Monday, November 19, 2001 6:44 AM
> >> > To: [e-mail]
> >> > Cc: [e-mail]; [e-mail]
> >> > 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 Chann
> >> > elStatus
> >> > message...".
> >> >
> >> > I agree that the suppression of downstream alarms is an
> >> > important issue.
> >> >
> >> great!
> >>
> >>
> >> > 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 f
> >> > aults occurring
> >> > upstream. The 3R points on the OLS Line Systems would
> >> > insert some type
> >> > of signal downs
> >> > tream. 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.
> >> >
> >> For interaction between cross-connects and Line Systems,
> >> please see OLI
> >> Requirements document
> >> (
> >> http://search.ietf.org/internet-drafts/draft-many-oli-reqts-00.txt
> >> ) and
> >> corresponding LMP-WDM protocol document (new version to
> >> be uploaded
> >> tomorrow, but old version can be found at
> >> http://search.ietf.org/internet-drafts/draft-fredette-lmp-wdm-02.txt
> >> ).
> >>
> >>
> >> > Any other views?
> >> >
> >> > Carmine
> >> >
> >> >