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RE: [T1X1.5] Re: Suppression of Downstream Alarms...
George,
This note makes a lot of sense.
Thanks,
Jonathan
> -----Original Message-----
> From: George Young [mailto:george.young@meriton.com]
> Sent: Wednesday, November 21, 2001 6:37 AM
> To: Carmine Daloia
> Cc: ccamp@ops.ietf.org
> Subject: RE: [T1X1.5] Re: Suppression of Downstream Alarms...
>
>
> Hello Carmine,
>
> For span protection, LMP can stand on its own, localizing the fault,
making sure
> that both ends of the fault span know about the failure.
>
> In a transparent network (which is where my company is focused), the node
at the receive
> end of a faulty link, and any nodes downstream (in the data flow
direction) become aware
> of the fault, so one end of the path knows almost immediately.
>
> For path protection, there would still be a need for signalling to the
other end. The benefit
> of using LMP to localize the fault, is that only one node need initiate
> the signalling to the
> head and the tail of the connection to toggle to the backup path.
>
> Regards,
> George R. Young
> Meriton Networks Inc.
> 329 March Rd., Kanata, ON, Canada, K2K 2E1
> phone: +1 613-270-9279 Ext 287
> fax: +1 613-270-9268
>
> -----Original Message-----
> From: Carmine Daloia [mailto:daloia@lucent.com]
> Sent: Wednesday, November 21, 2001 9:23 AM
> To: George Young
> Cc: ccamp@ops.ietf.org
> Subject: Re: [T1X1.5] Re: Suppression of Downstream Alarms...
>
>
> Hi George,
>
> Thanks for the pointer to your draft. I will definitely read over it.
> Just looking at it quickly and understanding what is in LMP, it seems
> that even under path protection/restoration, there is an intermediate
> node that detects a failure (and localizes the failure to ensure that
> the failure occured on that particular link) and then signals over the
> control plane to the head-end and tail-end nodes of the
> protection/restoration domain to initiate protection/restoration.
>
> It seems to me that the tail-end and head-end nodes
> themselves would be
> able to detect the defect in the transport/user plane since the defect
> occured between the two ends and they can then coordinate
> switching for
> protection/restoration without having to wait for any notification
> message sent from an intermediate NE. This should improve the
> protection/restoration time since the head-end and tail-end won't need
> to wait for intermediate nodes to localize a fault and then
> signal over
> a control plane requesting a proteciton/restoration switch. Any
> thoughts?
>
> Thanks
> Carmine
>
> George Young wrote:
>
>
> Hello Carmine,
>
> Meriton Networks intends to use LMP as a fault localization
> mechanism in
> a network of
> our transparent optical switches, currently in the
> pre-production phase.
>
> I've done some discrete event simulation work to characterize the
> performance of an IP
> network in support LMP management signals, and the resulting
> signalling
> messages needed
> to initiate protection/restoration, and based on the results, have not
> seen any need to change
> our design direction.
>
> I've also written and submitted an IETF draft
> http://search.ietf.org/internet-drafts/draft-young-opt-nni-pro
> t-issues-0
> 0.txt
> dealing with the importance of control network performance,
> particularly
> when extended across
> multiple networks, and would appreciate any comments you might have.
>
> Regards,
> George R. Young
> Meriton Networks Inc.
> 329 March Rd., Kanata, ON, Canada, K2K 2E1
> phone: +1 613-270-9279 Ext 287
> fax: +1 613-270-9268
>
> -----Original Message-----
> From: Carmine Daloia [ mailto:daloia@lucent.com]
> Sent: Wednesday, November 21, 2001 8:29 AM
> To: Carmine Daloia
> Cc: Jonathan Lang; ccamp@ops.ietf.org; tsg15q11@itu.int; t1x15@t1.org
> Subject: Re: [T1X1.5] Re: Suppression of Downstream Alarms...
>
>
> 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: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 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
>
>
>
>
>
>