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RE: Optical Link Interface
Vasant,
Please see inline.
Thanks,
Jonathan
-----Original Message-----
From: Vasant Sahay
To: Mannie, Eric; Bilel Jamoussi; ''Andre Fredette' ';
''ccamp@ops.ietf.org' '
Sent: 7/30/2001 4:34 PM
Subject: RE: Optical Link Interface
>>>>>>>>From my point of view, I don't see any reason to replace a
protocol by
>>>>>>>>another one if they have the same functionalities.
>The misconception here is that they have the same functionalities and
>that LMP definition is complete. I believe there is a lot of discussion
>and thought that needs to go into LMP if used as basis for OLI. WDM-LMP
>being based on LMP will also suffer that thrash.
[Jonathan]...and NTIP is complete and will not suffer any thrashing?
>Let us start with reliable transport(or lack thereof).
>How are failures conveyed reliably from WDM to OXC ?
>
>LMP defines ACK messages, however I couldnt find any reference to how
>they should be used to recover lost messages.
[Jonathan]Failures notification is idempotent. LMP is optimized to
react to alarms rapidly and doesn't require stop-and-wait procedures.
Alarms are treated as independent events. Eash alarm is transmitted until
acknowledged (see Section 6). If an alarm status changes, prior to
receiving the Ack, the new status is simply transmitted.
For a procedural reference, LMP works very much like that of RSVP-TE
message Ids in RFC2961.
>WDM-LMP draft specifies that an ACK should be sent for each
>channelStatus message. This level of definition is far from complete.
>
>So the question is if a few hundred failures were reported, what is the
>nature of this ACK scheme for recovering lost messages ? Are we going
to
>recommend a stop and wait protocol or a sliding window protocol ? (A
>stop and wait scheme is easy to implement but slow at recovering
>messages ) Or is the recovery scheme beyond the scope of the protocol ?
[Jonathan]Currently, a window size is intentionally not specified. We
can add a recommendation in terms of message transmission and processing if
that is helpful.
>If a sliding window is chosen, the implementor will develop code to
>reinvent what TCP does and will have to go through a maturing cycle for
>his sliding window scheme. There will also be implementation issues
>with managing real time OS timers at application level.
[Jonathan]We certainly don't want to reinvent TCP. We don't need such a
heavy-weight protocol for this interface. What we need is a reliable
lightweight messaging protocol that can react to failures rapidly.
>Keep in mind the WDM vendors are not in the business of developing
>transmission protocols for reliablity.They need a solution that can be
>easily added to their existing systems, many of which are legacy
>systems.
>
>In contrast NTIP has thought through these issues and uses TCP as the
>reliable transport.
>
>
>To start with that is one fundamental difference in the transport of
>NTIP vs LMP or WDM-LMP
>
>I am concerned about such open items in LMP which will come to haunt
OLI
>later.
>
>Vasant
-----Original Message-----
From: Mannie, Eric [ mailto:Eric.Mannie@ebone.com
<mailto:Eric.Mannie@ebone.com> ]
Sent: Monday, July 30, 2001 3:21 PM
To: Jamoussi, Bilel [BL60:1A00-M:EXCH]; ''Andre Fredette' ';
''ccamp@ops.ietf.org' '
Subject: RE: Optical Link Interface
Dear all,
>1. The stats are not that significant, since there was no "last call"
period announced in advance to gauge community interest.
Well, at least it shows some preferences for a specification based on an
existing protocol on which the IETF is working since a while and that
was
accepted as a WG document.
From my point of view, I don't see any reason to replace a protocol by
another one if they have the same functionalities.
So,
LMP-WDM: 8 + 1 = 9.
Kind regards,
Eric
Eric Mannie
EBONE
-----Original Message-----
From: Bilel Jamoussi
To: 'Andre Fredette'; 'ccamp@ops.ietf.org'
Sent: 7/30/01 5:14 PM
Subject: RE: Optical Link Interface
Andre,
2 comments on you statistics, then a proposal to progress:
1. The stats are not that significant, since there was no "last call"
period announced in advance to gauge community interest.
2. I do not think IETF uses company affiliation when measuring
consensus. If it did, then the fact that 3 from Nortel are supporting
NTIP, is an indication that there is an immediate need for NTIP given
Nortel is a key player in this space.
------
All,
Now to focus the discussion back on the OLI solutions (NTIP or LMP-WDM,
or a merged version),
- There is consensus on a single protocol which I respect.
- Key distinctions between NTIP and WDM-LMP:
1. WDM-LMP assumes that LMP is a priority, people will implement LMP,
hence WDM-LMP is a natural extension. The issues here are:
(a) this assumption is not accurate, the functions of NTIP (or WDM-LMP)
are more urgent than LMP
(b) there is significant baggage to be carried from LMP down to the
WDM-LMP
2. WDM-LMP assumes a peer model between the OXC and the WDM system. The
issue:
- this model doesn't reflect the reality that OXC and WDM are two
different devices - the OXC-WDM relationship is client-server one.
I suggest merging the two proposals as follows:
- remove unnecessary LMP baggage
- adopt a client-server model
- allow for TCP as the transport
- clarify a simplified autodiscovery mechanism
Bilel.
-----Original Message-----
From: Andre Fredette [ mailto:fredette@photonex.com
<mailto:fredette@photonex.com>
< mailto:fredette@photonex.com <mailto:fredette@photonex.com> > ]
Sent: Thursday, July 26, 2001 2:52 PM
To: ccamp@ops.ietf.org
Subject: RE: Optical Link Interface
From my count on the mailing list we have the following results so far:
LMP-WDM: 8
NTIP: 3 (All from Nortel)
Agnostic: 1
And then there are the other 16 co-authors of LMP-WDM who haven't posted
(perhaps because they don't think they have any new points to add).
Andre
At 02:00 PM 7/26/2001 -0400, Martin Dubuc wrote:
>Kireeti,
>
>I have been following this thread with great interest. I agree with
your
>conclusion that we should pick one protocol and move forward.
>
>You are talking about WG reaching a consensus. I cannot see how this is
>possible given the two very different views I see in the latest email
>exchanges.
>
>How can we resolve the current dispute? What forum should we use to
make
>a final decision on this?
>
>Martin
>
>-----Original Message-----
>From: Kireeti Kompella [ mailto:kireeti@juniper.net
<mailto:kireeti@juniper.net>
< mailto:kireeti@juniper.net <mailto:kireeti@juniper.net> > ]
>Sent: Wednesday, July 25, 2001 9:57 PM
>To: jamoussi@nortelnetworks.com; kireeti@juniper.net;
>osama@nortelnetworks.com
>Cc: bon@nortelnetworks.com; ccamp@ops.ietf.org;
>vasants@nortelnetworks.com
>Subject: RE: Optical Link Interface
>
>
>Hi Osama,
>
> > Even though I don't think reviving CR-LDP and RSVP-TE history will
get
>us
> > anywhere
>
>"Those who forget (ignore) history are doomed to repeat it."
>
>Yes, it makes for painful recollections. We're living with the
>consequences now, though, and I don't want to again.
>
> > the existence of two protocols here have proven to be useful.
>
>That's not what I'm hearing, either from customers, or from the
>WG (admittedly, the sample is small).
>
>Listen carefully: I don't want LMP-WDM and NTIP moving forward.
>Just NTIP (or NTIP and LMP) is OKAY if that is what the WG
>consensus is. LMP-WDM and LMP works too.
>
>So: you've got the WG chairs (scarred and grumpy), the ADs
>and TA (speak up if I'm misrepresenting you), and customers
>saying, Pick one protocol and move forward. Let's do that.
>And, please, as Vijay says, let's resolve this already.
>
>Kireeti.