Fong, This is
not NTIP requirement. It is an OLI requirement as stated in the requirement
draft. … and how
exactly do you propose those sensible implementations to inter-work. Regards; Osama Aboul-Magd Nortel Networks P.O. Box 3511, Station "C" Ottawa, ON, Canada K1Y - 4H7 Tel: 613-763-5827 e.mail: osama@nortelnetworks.com -----Original
Message----- Hi
Vasant I have
been watching this thread for a while. I believe both LMP, LMP-WDM, and NTIP
bring contribution to the OLI requirements. Single out requirements from NTIP
is not a fair statement since LMP/LMP-WDM can claim the same for bringing
in the importance of link verification and control channel maintenance
etc.. More
comments below. Best Regards, -Fong -----Original
Message----- Andre,
Jonathan, Besides
broken reliable transport in LMP I will like to list a few more items here. Let
us start with "resynchronization across OLI". When an
LMP session fails for some reason and recovers later, WDM-LMP or LMP do not
mention the requirements or behavior for any resynchronization to recover the
defect reports that might be lost during that window. NTIP has
thought through these behaviors. [Fong]
It is quite often that MPLS/GMPLS authors leave this level of details to
sensible implementations. Sending LinkSummary message after re-establishing LMP
adjacency is sensible implementation. :-) NTIP
sessions go thru a resync process upon a restart. During resync, WDM and OXC
exchange information on the failures/defects that might have been lost while
the session was down. Also, if the NTIP session went down while OXC
instructed the WDM to start monitoring some ports for defects or for trace,
obviously the command would be lost. NTIP resync also recovers such lost
commands. [Fong]
This is easily supported by adding a data-link sub-TLV in LinkSummary
message. NTIP has
also thought thru related requirements regarding persistence of information on
equipment. WDM-LMP or LMP has no thought on such issues. For
example if a WDM box reboots for some reason, should it remember which ports it
was supposed to monitor for defects and trace ? Or should the OXC instruct it
again for which ports to monitor ? If WDM equipment has to remember which ports
it had to monitor, it translates into a requirement for WDM to have persistent
storage. As mentioned
above NTIP resync process solves these issues. For details please refer to
NTIP draft .--) [Fong] I
am not quite sure NTIP thought through its requirement of WDM persistent
storage either :-) Since the Configuration update message has
CStat but there is no message for a PXC to configure the WDM. This translates
to NTIP also requiring persistent store. If this is the case, why would the
monitor and trace request not be in persistent store ? If the model is
that the OLS does not have persistent store, then it would not know which port
is enabled and would not be able to report a Configuration state. Can you
clarify ? The
point is to show that NTIP has thought through issues specific to OXC-to-DWDM
interface. LMP and WDM-LMP have not. Vasant -----Original
Message----- Andre, >>>>>>
Funny you should say this given that the colleagues you reference in your note
claim that LMP is not needed at all. I am wondering how we can keep our discussion positive and
constructive instead of pointing out assertions or getting into legal analysis
of statements. My
statement neither confirms nor denies my colleague's stand on "need for
LMP". The statement simply is "Andre if you were to base OLI on LMP
you will suffer the baggage". >>>>>>> I believe (with a lot of other
people) that the use of TCP for this protocol is broken. Please refer to
the numerous previous posts regarding this issue. [Sahay, Vasant ] If we used TCP for LMP it will certainly be broken because
LMP is a WAN protocol and has to consider round trip delays, variable
losses and congestion. But not so for NTIP. NTIP runs in a controlled local
environment where the congestion control sophistications can be disabled. By the way, we are not married to TCP. In fact while
co-authoring the OLI requirements we have only asked for a reliable transport.
It can be one of the many available prorocols used for reliable transport. The fundamental difference (in reliable transmission)
between NTIP and LMP is that NTIP is layered to run over a reliable transport
protocol, whereas WDM-LMP has an application implementing the reliablity. Also, in this context, on the LMP-baggage front, you will
need two flavors of retransmission schemes one for WAN (LMP) traffic, and the
other for local traffic (WDM-LMP). Does that sound like extra work
?
>>>>>>>>>Furthermore if you want
to compare true protocol complexity, add the TCP states and events to your NTIP
count, handle fail-over of TCP sessions, and then come talk to me. The complexity of a readymade module is not a consideration.
The complexity of WDM-LMP and LMP code to be developed is the question here.
The objective is to compare the development and integration risk and not the
states within TCP or any existing transport protocol for that matter.
Vasant ---Original
Message----- Vasant, Andre,
Besides, reliable transport of failure-messages is broken in LMP.
The current LMP and WDM-LMP drafts imply that the application will have to
build a mechanism for tracking and retransmitting lost messages. This
translates into additional baggage for OLI.
-----Original Message----- From: Bilel Jamoussi [mailto:jamoussi@nortelnetworks.com] Sent: Monday, July 30, 2001 8:14 AM To: 'Andre Fredette'; 'ccamp@ops.ietf.org' 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. [John Drake] This is silly. Who else would you like to hear from? 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. [John Drake] The fact that you perceive yourself to be a key player shouldn't a
priori give your opinion any additional weight ------ 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 [John Drake] What is the basis for this assertion? When we started
the LMP-WDM work we asked you to work on it with us and you refused, citing lack of need. (b) there is significant baggage to be carried from LMP down to
the WDM-LMP [John Drake] You've made this assertion inumerable times, and have been asked
inumerable times to enumerate what this excess baggage is. You have yet to do so. 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. [John Drake] This is an assertion. Some of the co-authors of the LMP WDM
draft work for WDM vendors and they're happy with the peer relationship between the two devices I suggest
merging the two proposals as follows: - remove unnecessary LMP baggage [John Drake] Once again, this would be what? - adopt a client-server model [John Drake] No - allow for TCP as the transport [John Drake] No one but you and your co-authors think that this is either
necessary or desirable - clarify a
simplified autodiscovery mechanism Bilel. -----Original Message----- From: Andre Fredette [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] >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. |