Re: [Pce] Some key issues with Wavelength Switched Optical Networks...

[Martin Vigoureux <martin.vigoureux@alcatel-lucent.fr>]

Hi Greg,

please see below

best regards,

martin

Greg Bernstein a écrit :
> Hi Igor, see comments below.
>
> Igor Bryskin wrote:
> > Greg,
> >
> >  
> >
> > I believe the draft is very useful.
> --> Thanks!
> >  
> >
> > I have a couple of questions comments:
> >
> >  
> >
> > 1. Section : 4.4. Traffic Grooming: Combining WSON and Higher Layer Network 
> >
> >    Optimization
> >
> >  
> >
> > How the problem of grooming of higher layer network traffic over 
> > optical trails is any different from the problem of traffic grooming 
> > in TDM (e.g. VC12 over VC4)? I mean this is a general problem of 
> > inter-layer relationship. I suggest moving all higher layer network 
> > considerations out of scope of the draft and focusing on specifics of 
> > the OCh layer.
> --> Some of my co-authors agree with you on moving this section out.  
> The reason that I put it in was that the optical "Traffic Grooming" 
> problem has received a fair amount of attention in the research and 
> general technical literature and is also a driver for the use of ROADMs 
> (optical bypass).  I guess in general we've got the following 
> inter-related problems: (a) virtual network topology design, (b) lower 
> layer connection routing, (c) higher layer flow routing. In our case (b) 
> is the RWA problem, which is fairly difficult in its own right. I guess 
> I should look closely at the MLN/MRN work and see if a specific example 
> that includes RWA is mentioned.  If so then I'd feel fine removing this 
> section from the document.

Optical considerations are not explicitly covered in MRN/MLN documents
anymore, but we still talk a lot about virtual topologies in
multi-layer/region contexts.
Optical considerations were covered at the very beginning of these 
documents, at the time they were called HPN (Hybrid Photonic Networks).
http://www.tools.ietf.org/html/draft-vigoureux-ccamp-gmpls-architecture-hpn-00