Re: Suppression of Downstream Alarms...

[Carmine Daloia <[e-mail]>]

Hi Sudheer,

I was assuming PXCs and not necessarily support for G.709.

Carmine

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
>>>>
>>>>