Re: Suppression of Downstream Alarms...

[Sudheer Dharanikota <[e-mail]>]

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
>> >
>> >