Re: [T1X1.5] Re: Suppression of Downstream Alarms...

[Maarten Vissers <[e-mail]>]

Dimitri,

It looks like we should separate the generic part of LMP from the technology
specific parts.

One of the technology specific parts is pre-OTN/WDM transporting STM-N/OC-N
signals. If the specification for this technology would be present in a separate
document, it would be much better understood that those requirements are only
bound to that technology, not to any of the other technologies (e.g. SDH/SONET,
OTN).

Regards,

Maarten

Dimitri Papadimitriou wrote:
> 
> 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
> > >> >
> > >> >