Subject: RE: Information about optical routing in MPLS net.

From: [email-masked]
Date: Wed, 14 Jun 2000 18:01:45 +0100

[Harrison,N,Neil,INC1 X]  <snip>
AB wrote: 
> > a. Considering explicit paths calculation through an optical MPLS
> > network, ingress
> >     routers or third part tools, at the input of the network, will still
> > calculate the
> >     entire path (ingress to egress router), considering links within the
> > optical domain
> >     too?
> > 
	[Harrison,N,Neil,INC1 X]  YX answered: 
> There have been discussions about this before. My personal opinion is that
> having router control optical domain is not feasible both technically and
> practically. 
> 
	[Harrison,N,Neil,INC1 X]  I would like to support YX's comments here
based on a practical observation:

	The optical L1 will have many client layers it needs to support.
For example, operators may have:
	-	large BW clients supported directly off the L1
	-	less coarse BW clients supported off trad L2 technologies,
eg FR and ATM....and even with MPLS VPNs it is almost certain that some
customers will still want hard BW partitioned L2 services for many reasons
(eg to get othogonal and robust availability SLAS and QoS SLAs, to run their
own customised DiffServ regimes, etc)
	-	PSTN clients
	-	MPLS/IP clients

	The addressable trail access points of each of these clients are not
congruent with each other.  Therefore they cannot be congruent with the L1
addressable trail access points.  Architecturally, the (inter-node) links in
a client layer are created from trails in the server layer........that is,
the L1 addressable trail termination points are only mid-points in the
client layer trails.  Another way of looking at this is that L1 forms an
important TE function for its clients, since by definition it creates their
topologies.

	Hence, any operator wishing to support a multiple set of client
layers cannot afford to have the optical L1 linked to any one of the
addressing regimes of a single client layer.  It therefore follows that the
optical L1 needs to be able to choose best-of-breed for its control-plane
wrt addressing, routing protocol and signalling protocol.......though the
latter 2 facets can re-use technologies they are not operating in the same
addressing space.

	Hope this makes sense.

	Neil

---

From: Mark Jones <[email-masked]>
Date: Thu, 15 Jun 2000 14:46:43 -0500

[My apologies for the long post.]

The complete control of the optical network by IP routers may be 
interesting, but it's not practical in a real 
multi-service/multi-client network.  At Sprint we have two perspectives 
on what the next optical network will look like.  One is that the 
optical network will consist of an all-optical core (my personal 
perspective).  In this case, the optical network may be controlled by 
client devices, but I see that as unlikely for many reasons (many of 
which were expressed well by Neil Harrison in his post on the subject 
yesterday).  The other option is that the optical network nodes will be 
mega-multi-service devices that will be fully IP capable.  In that case 
the nodes may look like an IP routers to clients and full "peer" 
communications is probably likely.

Either way, the IETF efforts regarding optical network control should 
not ignore the standardization of the optical network itself.  
Regardless of how many drafts and RFCs are generated, most of the 
optical transport expertise is not in the IETF.  Though it's tempting 
for every standards body to standardize the world, we all benefit most 
if each sticks with standards where one has the most subject matter 
experts.

Coordinated efforts to standardize the optical transport network are 
underway in ITU-T SG13, ITU-T SG15, T1X1, T1M1, and many other 
standards development organizations.  Efforts in those bodies are just 
now beginning to look at signaling and control plane issues.  It is a 
common view in those groups that MPLS, with extensions for optical 
network management, may become the control plane protocol of choice.  
However, I haven't seen any communication between this body and those 
transport groups.  How can we expect control anything when we aren't 
communicating with the groups on the other side of the control plane 
interface?  (Within companies this is happening, I know, but I'm afraid 
that even there communications are limited between the different 
departments.)

My point is that the IETF efforts need to focus on the requirements for 
the management interface and work with the transport standards groups 
to reach agreement on how this common control plane will supply the 
necessary information for communications both directions (client 
network elements to optical network and visa versa).  All these groups 
are now working via e-mail distributions lists, so it's not that 
complicated.

T1X1 and ITU-T are beginning to define what has been called an 
"Automatically Switched Optical Network."  The rough first draft of an 
ITU-T standard on the subject is publicly available at 
ftp://ftp.t1.org/pub/t1x1/x1.5/0x151280.doc.  Perhaps the IETF work in 
this area could provide useful input to help reach a common goal, a 
common control plane for dynamic connections over an optical network.  
The next meeting of T1X1 is July 11-14, in Ottawa, Ontario, Canada 
(http://www.t1.org/t1x1/_x1-man.htm).  No membership or registration is 
required for attendance.  More information on T1X1 is available from 
the T1X1 homepage at http://www.t1.org/t1x1/t1x1.htm.  I stress T1X1, 
because the ITU-T requires full membership for attendance at meetings 
or participation on their e-mail exploders.

Mark Loyd Jones
Sprint
Technology Planning & Integration
913-534-5247
[email-masked]

-----Original Message-----
From: xuyg [mailto:[email-masked]]
Sent: Thursday, June 15, 2000 12:29 PM
To: clapp
Cc: xuyg; darren.freeland; mpls
Subject: FW: Re: Information about optical routing in MPLS net.

Following the point from Darren, 

Optical layer is open to ALL clients, e.g. ATM, TDM, SONET/SDH and IP. 
If you
don't like the client/server model, optical network can also be viewed 
as a
cloud, which can be tunneled through (please refer to "Hierarchical 
Tunnel
Establishment in RSVP-TE" discussion). No matter what, optical network 
try to
achieve true networking rather than simple connectivity or bandwidth. 
It's as
complicated as pure IP network with many concerns that are unique to 
optical
domain. Also its protocol will evolve mainly independently from IP 
(sure will be
affected by IP). So I think IP router should focus more on how to 
request
service from optical domain than to directly control it.

Yangguang

[email-masked] wrote:
> 
> I would support the view that having the router control the optical 
domain
> is not good.  This comes down to a simple desire to see an optical 
layer
> which is open to ALL clients - not just IP.  Of course it is possible 
to
> allow the router to control the optical layer ... however, this idea
> overlooks the fact that an operator may wish to carry many other 
clients
> across an optical network.
> 
> Regards,
> 
> Darren Freeland
> Networks Analyst
> BT Adastral Park
> 
> -----Original Message-----
> From: George Clapp [mailto:[email-masked]]
> Sent: 15 June 2000 17:09
> To: Yangguang Xu
> Cc: [email-masked]
> Subject: Re: Information about optical routing in MPLS net.
> 
> At 11:26 AM 6/14/00 -0400, Yangguang Xu wrote:
> >Please see comments below:
> >
> > >
> Could you give some examples of why it's not feasible?
> 
> Thanks,
> George Clapp
> voice     973-829-4610
> email     [email-masked]

---

From: "Shaw, Robert" <[email-masked]>
Date: Thu, 15 Jun 2000 23:01:54 +0200

> optical transport expertise is not in the IETF.  Though it's tempting 

It's a general problem. A lot of IETFers aren't familiar with ITU-T 
IP-related work... :-)

For example, for only the 2 ITU-T Study Groups you mention (13 and 15),
I'll give a brief summary of their current work as it relates to IP 
and a few references (some of which are only available to ITU-T members 
through password access):

ITU-T Study Group 13

Study Group 13 (http://www.itu.int/ITU-T/com13/index.html) is 
the ITU-T lead Study Group on IP. In this role, SG 13 maintains 
the "ITU IP Project Description" describing the status of ITU-T 
IP-related activities and specific study "Questions". The last
version of this from their February/March 2000 meeting is 
available at 
http://www.itu.int/ITU-T/com13/ip/documents/pl-22.doc in Word (.pdf
for the PDF version). SG 13 has also defined a framework 
for the "Y" Series of Recommendations that cover ITU-T IP-related 
standardization activities (see 
http://www.itu.int/ITU-T/com13/ip/y1000.html). The report of 
SG 13's last meeting in February/March 2000 contains considerable 
detail on the scope of ITU-T's IP-related work (see
http://www.itu.int/itudoc/itu-t/com13/reports/report2/r068.html).

At its March 2000 meeting, SG13 approved Recommendation Y.1310: 
Transport of IP over ATM in Public Networks (see 
http://www.itu.int/newsroom/press/releases/2000/01NP.html)

Study Group 13 has a number of ongoing IP-related standardization 
projects (most in the ro68.html report above) including, inter 
alia: 

* Y.iptc: Traffic control and congestion control in IP networks;
* Y.1231: IP access network architecture;
* Y.1241: IP transfer capability for the support of IP-based services;
* Y.1310.1: IP Virtual Private Networks;
* Y.1310.2: IP-MPLS transfer and control protocols;
* Y.1401: General requirements for interworking with IP-based networks;
* Y.1530: Call processing performance for voice service in hybrid IP 
          networks; 
* Y.1540: IP packet transfer and availability performance parameters;
* Y.1541: IP performance objectives and allocations (relates to QoS 
          classes); 
* Y.17oam: Operations and Maintenance ("OAM") and protection switching 
           for IP-based networks.

ITU-T Study Group 15

Study Group 15 (http://www.itu.int/ITU-T/com15/index.html) is active 
in standardization in the area of transport networks, systems and 
equipment. It is the lead Study Group on Access Network Transport 
("ANT") and co-coordinates with Study Groups 4, 6 and 13 ITU-T 
activities related to the Optical Transport Network ("OTN") and 
Optical Networking technologies. During the last study period (ITU
parlance for 4 years), SG 15 revised eight and prepared one new 
Question (this is sort of an IETF wg charter) reflecting the shift 
in the telecommunications environment towards networks optimized 
for the transport of IP-type traffic.
 
Since then, SG 15 has carried out significant standardization work 
related to high-speed network access over copper wire loops using 
Digital Subscriber Line ("DSL") and optical fiber technologies, 
Synchronous Digital Hierarchy ("SDH") and the OTN. These have 
enabled the deployment and management of optical access networks 
for delivery of broadband services to both residential and 
business customers. 

For example, to facilitate network access over ordinary telephone 
subscriber lines, a set of six DSL-related Recommendations (G.990 
Series) have provided for multi-Megabit/s access to the Internet, 
private IP-based networks and other data network architectures. 
In the area of SDH, new and revised Recommendations have provided 
for high-capacity network protection and restoration, carriage of 
40 Gbps client signals and SDH network management. With regard to 
optical systems, new Recommendations have been prepared for single 
channel optical systems with bit rates up to 40 Gbps and for 
multichannel Dense Wave Division Multiplexing ("DWDM") optical 
systems. Significant progress has also been made on a new Network 
Node Interface ("NNI") specification for the OTN. Further advances 
have been made on completing Recommendations dealing with optical 
submarine cable systems and optical components and sub-systems.

SG 15 is proposing a broad suite of further work related to IP-based 
networks including, inter alia:  

* enhancement of several SG 15 Recommendations (e.g., G.983.1 and 
G.983.2) dealing with broadband optical access systems based on 
Passive Optical Networks ("PON") to better accommodate IP traffic;

* study the need for enhancements of xDSL Recommendations to optimize 
the transport of IP and IP-based services;

* study General Switched Telephone Network/Internet Protocol gateway 
equipment known as "Transport Network Equipment for Interconnecting 
the GSTN to networks optimized for Internet protocol and ATM 
Networks" ("TIGIN");

* work on optical transport of Internet packets ("IP over WDM", 
planned as Y.1330 ).

At its April 2000 meeting, SG 15 determined a new Recommendation 
G.871 on the "Framework for Optical Transport Network Recommendations" 
providing an overview of ITU-T Recommendations on different aspects of 
OTNs, the framework for their development, and a time frame for the 
development of updated or new Recommendations.  

Bob
--
Robert Shaw <[email-masked]>
ITU Internet Strategy and Policy Advisor
International Telecommunication Union <http://www.itu.int>
Place des Nations, 1211 Geneva, Switzerland

---

From: CATANZARITI Sergio FTR&D/TI <[email-masked]>
Date: Thu, 15 Jun 2000 15:08:03 -0700

Mine was not an MPLS/IP biased opinion. I was only trying to say that using
IP to carry full-fledged control plane information for a multi-client
optical network is not an assumption validated enough today to be accepted
as a basis for a universal (key adjective) Optical Internetworking control
model and mechanisms. Again, at least in carriers PMOs. This has nothing to
do with the multi-protocol (mainly data plane) support of MPLS. 

Sergio

> --------------------------------------------------------------------
> Sergio Catanzariti
> Senior Project Manager, Technology Integration
> France Telecom R&D 
> 1000 Marina Boulevard Suite 300 
> Brisbane CA 94005
> Tel. 650-875-1526
> Fax. 650-875-1505
> email:[email-masked] 
> --------------------------------------------------------------------
> 
> 
> From:	Peter Ashwood-Smith [SMTP:[email-masked]]
> Sent:	Thursday, June 15, 2000 12:13 PM
> To:	CATANZARITI Sergio FTR&D/TI
> Cc:	'Tony Li'; [email-masked]; [email-masked];
> [email-masked]; [email-masked]
> >      > It would simply use the IP network as the out-of-band control
> plane.
> > 
> > Fully agree on the advantages. But, this is still an open problem rather
> than an acceptable and stable solution, at
> > least in today carriers operational models.
> > 
> > Sergio
> 
>     What you are seeing is a recognition by many folks that a PATH
> regardless of
> what we call the labels can be controlled by MPLS (if the MPLS protocols
> are 
> suitibly generalized). What actually goes over these paths can be
> anything. After
> all, that is the "MP" part of "MPLS".
> 
>     Constraint based, distributed source routing with an OSPF/IS-IS style 
> topology database are the preferred solution to path oriented routing
> problems
> and have been used for a number of years now in ATM and proprietary
> systems
> so it is only natural to extend them to Optical networks.
> 
>     Cheers,
> 
>     Peter Ashwood-Smith

---

From: Mark Jones <[email-masked]>
Date: Thu, 15 Jun 2000 17:39:24 -0500

Thanks, Bob.

I'm sure the IP related work at the ITU-T is of most interest to the 
IETF.  I hope information like this will encourage more interworking of 
the IETF and the ITU-T.

However, I was trying to draw attention to the fact that many other 
groups are working on standardizing the optical network, which the IETF 
MPLS WG is expecting to manage.  As your summary shows, that work is 
not a function of the current ITU-T IP work.  IP is considered only as 
one of the many clients of the optical network in the current work.  
The optical network control plane discussions will soon become a big 
topic at T1X1 and the ITU-T, given the introduction of the G.ason work. 
 The IETF input and involvement might result in a common standard on 
the subject of the optical network control plane.

I mentioned the open policies of T1X1, because of the restrictions to 
participation in the ITU-T.  T1X1 has been coordinating U.S. input into 
the ITU-T standards work on optical networking, among other things. 

Mark Loyd Jones
Sprint

-----Original Message-----
From: Robert.Shaw [mailto:[email-masked]]
Sent: Thursday, June 15, 2000 4:02 PM
To: Robert.Shaw; Jones, Mark L.; mpls
Subject: RE: Re: Information about optical routing in MPLS net.

ITU-T Study Group 13

ITU-T Study Group 15

Bob

---

From: [email-masked]
Date: Thu, 15 Jun 2000 23:51:32 +0100

Agreed, I should have been more clear/precise.....the addressing syntax can
be identical in *all* layers (if that is what one would like to see), but
the trails in each layer are not geographically congruent (with the key
point remaining that 'server layer trails create client layer links').

Thanks for pointing out this ambiguity Granville.

Neil

> From:	Grenville Armitage [SMTP:[email-masked]]
> Sent:	Thursday, June 15, 2000 11:33 PM
> To:	[email-masked]
> Cc:	[email-masked]
> [email-masked] wrote:
> 	[..]
> > Addressing in
> > the L1, which is the 3rd major facet of the control plane, cannot be the
> > same as any of its clients.
> 
> I think that statement claims more than is necessary for clarity in
> this discussion. It may be explicitly observed that there's
> nothing stopping Layer N from using endpoint addressing that is
> syntactically similar to addresses from Layer N+1 (which some might
> believe is excluded by the wording above). I could in principle build
> a FOO transport network where all the nodes had 32 bit
> addresses looking remarkably like IPv4 addresses, and build a regular
> IPv4, IPv6, or ATM network on top of it. FOO would simply be a new link
> layer as far as my 'regular' network was concerned. FOO could quite
> easily also use IP-derived routing protocols to establish and maintain
> edge to edge FOO paths (part of its control plane) between clients of
> the FOO service (whether or not its data plane looked anything like
> 'conventional' packet-based IP)
> 
> cheers,
> gja (who thinks the 6bone is an educational example...)
> ________________________________________________________________________
> Grenville Armitage                    http://members.home.net/garmitage/
> Bell Labs Research Silicon Valley