3BFBE4F0.A0F63471@nayna.com"> Hi again:Carmine Daloia wrote:
Agreed we need to focus on LMP not DWDM-LMP :-) But...3BFBC983.D84D3696@nayna.com">Ok Let us address the issues separately...
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.
1. Communication between Line System and Cross connect
Defining a bit-oriented (physical) interface and protocol is not really the task (in my opinion)
of IETF.
I am not sure if are creating a problem to solve with the alarm suppression.
Let me explain...3BFBC983.D84D3696@nayna.com">Let us assume we can correlate and suppress the alarms between the Line systemsAs I said, I am not suggesting that we need a bit-oriented protocol. My main point was that for the communication between the line-system and cross-connect, we need to understand the applications that require such communication and the requirements for those applications. It may be that the requirements can be met by carrying messages over IP (e.g., LMP-WDM). This is an issue for LMP-WDM and not for LMP (i.e., running between cross-connects) anyway. So for the sake of focusing some of this discussion let me suggest we focus on communication between the adjacent cross-connects and we can even assume that LMP-WDM handles the Cross-connect and Line System communication.
and corss connects. Then we donot need an elaborate bit-oriented protocol. This
has an assumption that we are talking about not hundereds of failures but a couple of
failures (for example fiber cuts).
the intention of the OLI document was to underdstand the requirements.
I thought most of us vouch for these requirements. Let us put the
requirements in the back-burner. If it is bit-oriented protocol it
does not interest most of us :-)Again... span protection can be performed easily with the current3BFBC983.D84D3696@nayna.com"> 2. Communication between cross connectsLocalize a fault for what reason? To understand if the fault is within the protection/restoration domain. For span protection/restoration the end-points of the domain coincide with the LMP end-points. For end-to-end protection/restoration the end-points do not coincide with the LMP end-points. Because the end-points of a protection/restoration domain do not always coincide with the end-points of a LMP protocol, I don't think it is a good idea to lump messages related to protection/restoration in LMP. It will result in similar messages having to be defined in other protocols and therefore a duplication of work and processing.THis is needed to localize a fault which in turn can be used as a trigger for local
restoration.
mechanisms supported by LMP in out-of-band communication
scenarios.In case of overlaping restoration scenarios such as span and end-to-end
it is required to have a localization + an attempt to recover + (if this fails)
report to end-to-end entities for recovery. THis also vouch for the
inclusion of such mechanisms in LMP.Well I guess I cannot buy this argument :-)
Will this duplication cause major issues in a network. I doubt it... but it just doesn't seem right from an architecture perspective.3BFBC983.D84D3696@nayna.com">Cheers,
sudheer
3BFBC983.D84D3696@nayna.com">
- sudheer
Thanks
CarmineSudheer Dharanikota wrote:
3BFBC412.E5FC940B@nayna.com"> 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
CarmineCarmine Daloia wrote:
3BFBA9CC.1060609@lucent.com"> 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
CarmineJonathan Lang wrote:
C12BBE1C7A8F7344808CD8C2A345DFB8455B10@pulsar.chromisys.com">Carmine,
Please see inline.
Thanks,
Jonathan-----Original Message-----
From: Carmine Daloia [mailto:daloia@lucent.com]
Sent: Monday, November 19, 2001 6:44 AM
To: ccamp@ops.ietf.org
Cc: tsg15q11@itu.int; t1x15@t1.org
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 noti
fication 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
upstr eam. The 3R
points on th
e 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