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

[Sudheer Dharanikota <[e-mail]>]

Carmine...

Again can you suggest a way to communicate such signals
between line systems and cross connects when inband
communication is not supported between these two systems?

Cheers,

sudheer

Carmine Daloia wrote:

> Jonathan,
>
> Forgot to mention, that the performance aspects of
> carrying OAM type signals over an IP based control channel
> in LMP-WDM would have to be analyzed. It is possible that
> the IP Control Channel will not provide fast enough
> transfer to actually suppress downstream alarms, however
> that needs to be analyzed as part of LMP-WDM.
>
> Thanks
> Carmine
>
> 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 Cha
>> >>  nn
>> >>  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
>> >>  faults occurring
>> >>  upstream. The 3R points on the OLS Line Systems would
>> >>  insert some type
>> >>  of signal dow
>> >>  ns
>> >>  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
>> >>
>> >>