Subject: RE: [Pce] New draft on wavelength switched optical networks

From: "MEURIC Julien RD-CORE-LAN" <[email-masked]>
Date: Fri, 13 Jul 2007 16:20:43 +0200

Hi Greg.

I'm really interested in this topic, but I think I've missed some points when reading your ID.

For instance, I don't get why you consider the signal modulation format. I don't believe a single-vendor environment would require a negociation on modulation for a specific bandwidth, and I don't think modulation information would be enough for 2 different implementations to interwork on (analog) optical line.

Anyway, this work is a good start to highlight GMPLS and PCE lack to handle the different kinds of optical networks.

Regards,

Julien

-----Original Message-----
From: Greg Bernstein [mailto:[email-masked]] 

Hi CCAMPer's and PCEr's, we have just published a new draft on the 
"Applicability of GMPLS and PCE to Wavelength Switched Optical 
Networks"  
http://www.ietf.org/internet-drafts/draft-bernstein-ccamp-wavelength-switched-00.txt 
.

This draft looks at optical networks that include tunable lasers and 
ROADM (reconfigurable optical add/drop multiplexers) with no or limited 
wavelength conversion capability (these components are defined in the 
draft). 
These limitations lead to the RWA (routing and wavelength assignment) 
problem which is a bit more demanding in terms of input information and 
computation than other constrained path computation problems.  In the 
draft we look at the implications for GMPLS signaling, GMPLS routing, 
and PCE protocols and suggest some potential extensions to better 
accommodate this application.

We'd appreciate feedback/collaboration on (a) overall interest in this 
application, (b) requirements discussions, and (c) solution/extension 
discussions.

Cheers

Greg B.

-- 
===================================================
Dr Greg Bernstein, Grotto Networking (510) 573-2237

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---

From: Greg Bernstein <[email-masked]>
Date: Fri, 13 Jul 2007 11:14:21 -0700

Hi Julien, good questions.  See comments below. 

Regards

Greg B.

MEURIC Julien RD-CORE-LAN wrote:
> For instance, I don't get why you consider the signal modulation format. I don't believe a single-vendor environment would require a negociation on modulation for a specific bandwidth, 
--> In the optical case as it is currently implemented I tend to agree 
with you here.  However in other systems negotiation of modulation 
format and such is more common.
> and I don't think modulation information would be enough for 2 different implementations to interwork on (analog) optical line.
>   
I was thinking along the lines of the relatively new ITU-T optical 
signal designations such as NRZ 2.5G, and RZ 40G defined in G.959.1.
I'm also, like most of the ITU-T recommendations, restricting the focus 
to digital signals over fiber. Not including impairment information for 
now, this should give us adequate information to understand the signals 
spectral characteristics for compatibility with wavelength selective 
switching elements and such.  At least this was the part of the point of 
the physical layers interfaces defined G.959.1. 

One thing that we might have not hit well enough is the compatibility of 
the end systems where the optical signals are demodulated. Its one thing 
to be able to switch the lambdas its another to demodulate them. Would 
we need more information or would this be covered in the PID?  For 
example if the PID indicates that the carried signal is a particular 
flavor of10G Ethernet that would be sufficient.  I'll review the current 
PID stuff as applied to lambda switching.