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

[Carmine Daloia <[e-mail]>]

Sudheer,

I am not assuming inband communication is supported between the 
cross-connect and the line system. That is why I said that when the PXC 
and line system are from different vendors such OAM signals would have 
to be carried over a separate channel (e.g., LMP-WDM control channel). 
However, I don't see why such signals would have to be carried over an 
LMP control channel between cross-connects. Also, my point about 
performance was that we would have to see if the LMP control channel 
would meet the performance requirements for such OAM signals. It very 
well might. If not, a bit-oriented signaling interface may be needed 
between the PXC and the line system.

Thanks
Carmine

Sudheer Dharanikota wrote:

> 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
>>>>>