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

From: [email-masked]
Date: Thu, 15 Jun 2000 22:58:15 +0100

Tony,

Please re-read my mail of yesterday.  I agree with what you are saying wrt
the routing protocol and signalling protocol of the L1 where we can re-use
existing technologies.....indeed, we would be seeking best-of-breed in this
respect.  But these are only 2 facets of the control plane.  Addressing in
the L1, which is the 3rd major facet of the control plane, cannot be the
same as any of its clients.  This is a 'truth' since the (addressable) trail
entities of the L1 only form link connections (ie a partition of a client
layer trail), and hence only co-locate with a client layer trail mid-point,
in any of the client layers.  Indeed, flexible client layer topology
construction (which is in essence  a part of the TE story - see Note) is a
key purpose of the L1 (besides supplying direct high BW customers).

Client layer trail span - between addressable access points
	<----------------------------------------->
	O--------O-----------------O-----------O
		|		|
		|		|
		0-----0----0-----0
		<------------------>
Server layer trail span - between its addressable access points

Note - TE has 3 time/granularity-scales:
-	physical duct/media build-out - large timescale, large
granularity....this is an operator's planning cycle for *all* its client
layer forcasts
-	L1 flexing of trails to create client layer topologies - medium
timescale, medium granularity....we need this to cater for uncertainty in
traffic vector forecasts in *each* specific client layer
-	within-layer techniques to bypass normal routing protocol, eg using
RSVP/CR_LDP say if we are considering only the MPLS client layer....we need
this for ad hoc traffic re-distribution at smaller timescales (eg during
failures, unexpected near-term congestion and other reasons, eg QoS related
facets).

I cannot honestly believe anyone who understands what is being stated above
wrt the L1 addressing can dispute it......especially any operators.

Regards, Neil

> -----Original Message-----
> From:	Tony Li [SMTP:[email-masked]]
> Sent:	Thursday, June 15, 2000 7:29 PM
> To:	[email-masked]
> Cc:	[email-masked]; [email-masked]; [email-masked]
> Subject:	RE: Information about optical routing in MPLS net.
> 
> 
>  | 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.
> 
> 
> The optical plane clearly needs a control plane that provides a (lambda)
> routing and signaling infrastructure.  This infrastructure is
> fundamentally
> similar to the routing and signaling technology that we're already using
> for MPLS.  Now, we can choose to re-invent this technology, or we can
> leverage the technology that we have already have developed and have
> started to deploy.
> 
> Note that this argument is completely independent of the nature of the
> optical client.  Nothing here precludes non-IP usage of the optical core.
> It would simply use the IP network as the out-of-band control plane.
> 
> Regards,
> Tony
> 
> 
>

---

From: Grenville Armitage <[email-masked]>
Date: Thu, 15 Jun 2000 15:33:09 -0700

[email-masked] wrote:
	[..]
> Addressing in
> 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

---

From: Yangguang Xu <[email-masked]>
Date: Thu, 15 Jun 2000 21:07:57 -0400

Besides client/server relation, networks at different layers can also be viewed
as autonomous peers. In this case, having network in different layers using the
same address scheme and sharing same address space could actually benefit and
simplify network interworking. However, this doesn't mean client has to control
the server layer network.

Yangguang

---

From: Dimitri Stratton Vlachos <[email-masked]>
Date: Thu, 15 Jun 2000 21:14:57 -0700

On a somewhat different note, in optical networks today, how dynamic is the 
control plane.  I.E. if a optical cross-connect is to be configured through 
a series of optical switches what signalling protocols are available today 
and how proprietary are they??

------
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