RE: I-D ACTION:draft-andersson-mpls-g-chng-proc-00.txt

["Lazer, Monica A, ALABS" <mlazer@att.com>]

Gert,
I think that one of the main drivers of the different needs when going
from L1 to L2 is the fact L1, in SONET is TDM-based, while L2 can be
packet based and have a different paradigm, while when going from HO to
LO one is within the same paradigm. So, point 1 indicates that one
should consider using the same control plane architecture for the
sublayers within L1, but it does not necessarily support the idea that
the same paradigm is best for both L1 and higher layers.  Regarding the
backbone/regional structure, more than only 2 levels may be needed for
global transport networks.

Regards,

Monica A. Lazer
Network Architecture and Reliability
 
908 234 8462
mlazer@att.com

-----Original Message-----
From: Gert Grammel [mailto:Gert.Grammel@alcatel.de]
Sent: Thursday, March 06, 2003 3:38 PM
To: Mark.Jones@mail.sprint.com
Cc: ccamp@ops.ietf.org; dwfedyk@nortelnetworks.com; Ash, Gerald R
(Jerry), ALABS; mpls@UU.NET
Subject: Re: I-D ACTION:draft-andersson-mpls-g-chng-proc-00.txt

Mark,

I am happy to read that we could find some common understanding. About
your
multi-layer issue you've raised, I suggest to figure out more to which
extend
this is an issue for UNI. Some thoughts on that:

  1. Wideband Crossconnects are able to crossconnect low order circuits
(LO),
     and put them into high order circuits (HO). Those Crossconnects are
managed
     by one manager able to control both Layers: LO and HO. I've never
heard
     that an operator let one part of the organization implement HO only
on a
     country wide basis, while another part of the organization is
taking care
     about LO only.
  2. So rather than the pure layering, a kind of regional/backbone
structure is
     in place. Regional NOCs deal with HO and LO whithin the region
while in
     backbone you use HO only because you don't need the finer
granularity
     there. So what appears to be a layering from a management point of
view
     seems to me more a regional kind of separation.

To be clear: I don't want to discuss the fact that there is a layering
in the
network. My point is to highlight that SDH/SONET is in reality not a
single
layer but has at least 4 of them (RS, MS, LO, HO). In theory we should
find in
the network an RS-manager, an MS-Manager, a LO-Manager and a HO-Manager.
Moreover a single Wideband Crossconnect would have had to be managed by
all 4
managers at the same time. Obviously this is not really practical
(immagine: 4
managers, one worker ;-) such that most vendors and carriers decided to
put all
4 layers into one management box - quite similar to what a GMPLS Control
Plane
does with SONET/SDH control.

Just to avoid misunderstandings here: I don't want to start a new thread
on
layering issues. I just want to provide you some food for your own
thoughts
hoping that we can find some common understanding at some point in
future.


Regards

Gert


Mark.Jones@mail.sprint.com wrote:

> Gert,
>
> Thanks for outlining the history and your current position for going
> forward.  Mostly, I agree with you.
>
> My major point of disagreement is with your characterization of the
> ITU-T direction.  Though the ITU-T ASON documents might enable
> "'Bandwidth on Demand' services (BOND)" to some degree, that was not
the
> primary focus.  The Optical UNI was a development that came out of the
> OIF and not the ITU-T.  Most carriers have seen the Optical UNI as a
> potential customer interface with far more realistic applications
> internal to networks, i.e. between the L3/L2 elements and the L1/L0
> elements.  Those who have attended the OIF in the past probably
remember
> my unpopular statement on the plenary floor that we were wasting out
> time working on a UNI that had questionable (no?) business advantages
> for the carrier.
>
> I do support the approach you mention (from Kireeti?) that we focus on
> the service points and the information that needs to be exchanged
> between them.  Where most of the services are of the L3/L2 variety,
that
> approach should be successful.  Those items should be fully covered by
> the IETF solutions.
>
> However, that doesn't address the multi-layer issue that we are
> struggling to address, which is one of the root causes of this
conflict
> between the IETF and ITU-T.  The signaling/control for L1/L0 is where
> the ITU-T participants have found the IETF solutions to be inadequate.
> That's not necessarily because the IETF solutions wouldn't work, but
> because they would not satisfy the stringent requirements and models
by
> which we base our management and control for L1/L0.
>
> This whole problem could be blamed on the IP success in the industry.
> If IP had not proven to be so successful, the ITU-T might have chosen
> the optical control plane based on extensions to SS7.  :-)  (Not
meaning
> to ignore the ITU-T alternative solution based on PNNI.)
>
> Regards,
>
> Mark Loyd Jones
> Optical Transport and Networking
> Sprint - Wireline Technology Development
> 913-794-2139
>
>
> -----Original Message-----
> From: Gert.Grammel [mailto:Gert.Grammel@alcatel.de]
> Sent: Thursday, March 06, 2003 1:21 PM
> To: Mark.Jones
> Cc: ccamp; dwfedyk; gash; mpls
> Subject: Re: I-D ACTION:draft-andersson-mpls-g-chng-proc-00.txt
>
> Mark,
>
> 'improving the coordination between the IETF and ITU-T' is one of the
> things I'd
> like to see since years. However in my experience the true barrier
> between both
> groups is not so much the technology as such, but some ignorance about
> the core
> aspects in both organizations. To give a balanced figure here:
>
>   1. You remember the thread about the non-standard SDH/SONET
> extensions. Here
>      some guys active in GMPLS tried to push their ideas about
> transparency.
>      Obviously this was perceived on ITU-T side as a challenge on the
> purity of
>      a standard (G.707). This one was (almost) setteled by moving all
>      non-standard features to an informal draft.
>   2. Now it is the other way round. Somehow ITU-T extensions got
> accepted (again
>      informational) in IETF which do not comply to the purity of
> RSVP-TE. Due to
>      the fact that this informational RFC was not reviewed in CCAMP
> before, it
>      is perceived as an assault.
>
> So the match is tied up 1:1 but maybe it's now the right time to find
a
> solution
> on how to proceed. What I've seen so far was a complete misperception
of
> what is
> required on either side and why.
>
>   1. ITU-T basically started by defining user services having in mind
> layered
>      transport platforms like OTH and SDH/SONET. Those services can be
>      summarized as 'Bandwidth on Demand' services (BOND). Naturally
this
> led to
>      a very strong focus on UNI interfaces and a kind of ignorance of
> networking
>      protocols. You probably remember the discussions on why not using
> SS7? (For
>      those not familar with the issue: SS7 is the signaling protocol
> between
>      PSTN switches)
>   2. IETF started with established L2/3 protocols (OSPF, RSVP-TE, ...)
> and
>      extending their scope to L1 technologies namely SDH/SONET and
OTH.
>      Naturally this led to a very strong focus on protocol consistency
> and a
>      kind of ignorance on service aspects other than those already
> available in
>      MPLS. You may remember here the discussion about whether UNI is
> useful at
>      all some time ago.
>
> So putting everything together means that it is required to keep
(IETF)
> protocol
> consistency but adding some (ITU-T) specific extensions to well
defined
> service
> points in the network (UNI).
> Unfortunately service points tend to exchange messages between
> themselves and
> this would mean that an intermediate protocol would have had to
support
> such
> kind of communication. What concerns the IETF community is probably
not
> the fact
> that there is a UNI somewhere, but the changes and extensions to
> etablished
> protocols in order to achieve a collaboration between them.
>
> I recall that this was the basic issue with the ITU-T proposal when it
> was
> presented for the first time in Yokohama. The way I've got Kireeti's
> message
> there was: please authors try to let us understand what problem you
want
> to
> solve and tell us which kind of information you have to exchange
between
> which
> points to achieve it. We'll sort out then in CCAMP what would be the
> most
> appropriate way to implement it, while maintaining consistency in our
> protocols.
>
> Although it didn't work the first time I still consider Kireeti's
> suggestion to
> be a wise way to move forward and perhaps the key for harmonic
> collaboration.
>
> Regards
>
> Gert
>
> Mark.Jones@mail.sprint.com wrote:
>
> > Gert,
> >
> > I agreed with the intent in generalizing MPLS for the wide range of
> > expected applications.  It was my hope that it would succeed.  At
this
> > point, one might say that the intent has only been partially
achieved.
> > The problem that has come to light over the past year is the fact
that
> > there are finer points of the ITU-T model and requirements that are
> not
> > supported by the current IETF GMPLS RFCs and standards track drafts.
> > Those aspects are considered significant enough by many carriers and
> > their suppliers to warrant further extensions outside of the IETF.
> (My
> > apologies for not understanding those points well enough to clarify
> them
> > even in examples, but there are many people on this list would could
> do
> > so if they thought it necessary.  To avoid any misunderstand, all
> should
> > know that Sprint does not yet have a company position on this.)  It
is
> > my hope that we can come up with ways of improving the coordination
> > between the IETF and ITU-T.  This thread of discussion is bringing
out
> > the issues to make that happen.
> >
> > Regards,
> >
> > Mark Loyd Jones
> > Optical Transport and Networking
> > Sprint - Wireline Technology Development
> > 913-794-2139
> >
> >
> > -----Original Message-----
> > From: Gert.Grammel [mailto:Gert.Grammel@alcatel.de]
> > Sent: Thursday, March 06, 2003 10:17 AM
> > To: Mark.Jones
> > Cc: dwfedyk; gash; ccamp; mpls
> > Subject: Re: I-D ACTION:draft-andersson-mpls-g-chng-proc-00.txt
> >
> > Mark,
> >
> > please don't forget that due to the 'Generalization' of GMPLS you
are
> > free to do
> > the split at any application level you wish. This was always the
> > advantage of
> > the GMPLS approach compared to the ITU-T model where initially each
> > layer had
> > its own control plane. So the fact that in theory you could use a
> single
> > control
> > plane for all your network means also that you are able to stop
where
> > you want.
> > Nice feature isn't it?
> >
> > Regards
> >
> > Gert
> >
> > Mark.Jones@mail.sprint.com wrote:
> >
> > > I agree with the separation of GMPLS into the two applications.
> There
> > > does not appear to be any significant move to collapse the
> management
> > or
> > > signaling for L3/2 and L1/0 at this time, given the different
models
> > > that apply for them and the infrastructures in our companies that
> > manage
> > > them.  The plan for addressing the two applications need not be
the
> > > same.
> > >
> > > The L3/2 application is near and dear to the heart of the IETF.
The
> > > L1/0 application is of interest to those who wish to collapse the
> > > management into a single layer.  In my opinion, the IETF might
also
> > > address this approach, given the IETF participants are the ones in
> > > support of this collapsed management or at least common protocol
> > > solution for what is today two signaling layers.  However, as
stated
> > > before, the collapse approach is not realistic today for a
> > > multi-service, multi-protocol network.
> > >
> > > On the other hand, the L1/0 application requirements and models
have
> > > been defined and are best understood at the ITU-T.  Ideally, the
> > > protocol expertise at the IETF would be applied to the ITU-T model
> and
> > > requirements to address the L1/0 application, but attempts to do
> that
> > > have been met with great resistance in the past.  Perhaps that was
a
> > > result of the fact that GMPLS implementations were not separated
out
> > > into the two different applications.  However, I don't think it is
> > > realistic to expect the IETF experts to be motivated to understand
> the
> > > ITU-T models and requirements, given the application is outside of
> > their
> > > primary area of interest.  That said, I believe the IETF should
> reach
> > an
> > > agreement on how to work with outside groups that develop "major
> > > extensions" to the protocol.
> > >
> > > Mark Loyd Jones
> > > Optical Transport and Networking
> > > Sprint - Wireline Technology Development
> > > 913-794-2139
> > >
> > >
> > > -----Original Message-----
> > > From: dwfedyk [mailto:dwfedyk@nortelnetworks.com]
> > > Sent: Thursday, March 06, 2003 7:49 AM
> > > To: gash
> > > Cc: mpls; ccamp
> > > Subject: Re: I-D ACTION:draft-andersson-mpls-g-chng-proc-00.txt
> > >
> > > Along the lines of Jerry's comments.
> > >
> > > When we put together GMPLS the first drafts were under specified
> > > intentionally to capture the essence of GMPLS. We put aside many
> > > arguments saying lets specify at a high level and fill in the
> details
> > > later. The discussions on this thread are in two major veins one
> > > attempting to fill the details and the other containing and
> > controlling
> > > the changes. GMPLS needs to be specified more accurately and in my
> > > opinion it needs to be decomposed to a more layered approach.  I
> think
> > > if we applied GMPLS at at some layers (L3/2), (L1/L0) for example,
> > > independently but self similar it would offer a mechanism to move
> > > forward where some legacy systems could be specified to be GMPLS
> > > friendly. For example signaling for Layer 3/2 can be tunneled
> through
> > > the a lower layer. We already have some work in this direction.
> > >  Similarly traffic engineering information for L1/L0 in a TE
> database
> > >  would need different  attributes than a the TE database at L3/2.
I
> > > don't think you want to burden a L3/L2 system with these
attributes
> in
> > > an overlay model. The expertise for these layer is not all
contained
> > in
> > > the IETF. I think we should put a plan forward to make this happen
> > > within the IETF process. After this was accomplished  I think some
> > > people are thinking of collapsing layers even more but the logical
> > > partitioning of layers may help keep the protocols and databases
> > > simpler.   Right now were are treating GMPLS like a big bowl of
> jelly
> > > when it should look more like a layer cake.
> > >
> > > Regards,
> > > Don
> >
> > --
> > Alcatel Optical Network Division    Gert Grammel
> > Network Strategy                    phone: +49 711 821 47368
> > Lorenzstrasse 10                    fax: +49 711 821 43169
> > D-70435 Stuttgart                   mailto:Gert.Grammel@alcatel.de
>
> --
> Alcatel Optical Network Division    Gert Grammel
> Network Strategy                    phone: +49 711 821 47368
> Lorenzstrasse 10                    fax: +49 711 821 43169
> D-70435 Stuttgart                   mailto:Gert.Grammel@alcatel.de

--
Alcatel Optical Network Division    Gert Grammel
Network Strategy                    phone: +49 711 821 47368
Lorenzstrasse 10                    fax: +49 711 821 43169
D-70435 Stuttgart                   mailto:Gert.Grammel@alcatel.de