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Re: Optical impairments in draft-ietf-mpls-generalized-signaling-04
Yangguang,
I understand your point and may be I haven't express well
mine.
I'm thinking about an All Optical network with limited lambda conversion (in the
sense that not all the PXC are lambda conversion capable) which is too large to
ensure that all potential routes have adequate Q at the end node.
In this scenario I must know, in order to plan a route that assures sufficient
Q, not only if a node is lambda conversion capable but also in which way it
performs lambda conversion.
I mean if conversion is done by OEO operated by classical transponder I have not
to worry about performance penalties (in fact I have 3R regeneration of the
signal) but if it is done in the optical domain (e.g. with Semiconductor Optical
Amplifier) I have to consider the loss introduced by this kind of conversion.
Suppose I have the following network scenario:
A----------B-----//-----C--------D---------E
A and E are source and destination node for a lightpath. Suppose that due to
optical impairments I have to regenerate electrically the signal between node C
and D I choose node C in order to have better Q at the receiver, then at node D
due to lambda unavailability I have to do WC but node D is able to do only OEO
conversion so I have two consecutive OEO conversion while just one is necessary.
On the other hand if I have sufficient budget to cover the whole path without
taking into account the penalties due to SOA lambda conversion if I do WC with
SOA I risk to degrade too much the signal.
Summarizing what I would like to say about WC is that it implies some
considerations on routing:
If I do OEO WC I restart the penalties counting
If I do optical WC I have to add penalties to the routing calculation.
This from my point of view impacts the way I calculate a route.
Thus lambda availability and signal degradation calculation must be taken into
account together, either during the routing or the signaling or both.
----------------------------------------------------------------
Diego Caviglia
Photonic Networks Design and Modeling
E-mail: diego.caviglia@marconi.com
Tel: +39 (0) 10 6003 808
Via A. Negrone 1A 16153 Genoa (Italy)
http://www.marconi.com
Yangguang Xu <xuyg@lucent.com> on 26/06/2001 15.13.16
To: Diego Caviglia/MAIN/MC1@MCMAIN
cc: Ayan Banerjee <abanerjee@calient.net>,
ccamp@ops.ietf.org, Giovanni
Fiaschi/MAIN/MC1@MCMAIN
Subject: Re: Optical impairments in
draft-ietf-mpls-generalized-signaling-04
Diego,
As indicated by the document that Ayan pointed to you, there are many constrains
for the optical networking. These constrains can be considered at network
planning time, path selection time (routing using OSPF-TE/ISIS-TE) or connection
setup time(GMPLS signaling). When a constrain is considered is an engineering
issue. We just have to figure out when and where is the best and cheapest to
consider a constrain. To wavelength conversion, GMPLS signaling is a good place
to handle.
Thanks,
Yangguang
Diego Caviglia wrote:
>
> Ayan,
>
> Thanks for your answer but I don't understand why lambda conversion
is
> a signalling problem and thus is covered in generalized signalling draft
while
> others optical impairments are routing problem and are covered in a
separate
> document.
>
> Moreover even if the document you quoted is a well written and very useful
one
> it is an informative contribution that simply points out the
physically
> impairments of an all optical network. It doesn't propose any extension
to
> OSPF/IS-IS in order to support optical routing.
>
> Given that in an All Optical Network we have to cope with lots of
new
> information, as you stated in your document, are we sure that OSPF, in
this
> environment, scales?
>
> I mean if it doesn't scale for wavelength availability information
distribution
> why it has to scales for other optical impairment distribution?
>
> ----------------------------------------------------------------
> Diego Caviglia
> Photonic Networks Design and Modelling
> E-mail: diego.caviglia@marconi.com
> Tel: +39 (0) 10 6003 808
> Via A. Negrone 1A 16153 Genoa (Italy)
> http://www.marconi.com
>
> Ayan Banerjee <abanerjee@calient.net> on 25/06/2001 22.26.02
>
>
>
>
>
>
>
> To: Diego Caviglia/MAIN/MC1@MCMAIN,
> petera@nortelnetworks.con, ccamp@ops.ietf.org
>
> cc: Giovanni Fiaschi/MAIN/MC1@MCMAIN
>
>
>
> Subject: RE: Optical impairments in
> draft-ietf-mpls-generalized-signaling- 04
>
>
>
--------------------------------------------------------------------------------
>
> Diego,
>
> Please see draft-ietf-ipo-impairments-00.txt for optical constraints.
>
> Thanks,
> Ayan
>
> -----Original Message-----
> From: Diego Caviglia [mailto:Diego.Caviglia@marconi.com]
> Sent: Monday, June 25, 2001 6:19 AM
> To: petera@nortelnetworks.con; ccamp@ops.ietf.org
> Cc: Giovanni Fiaschi
> Subject: Optical impairments in draft-ietf-mpls-generalized-signaling-04
>
> Peter ,all,
>
> a comment about draft-ietf-mpls-generalized-signaling-04. In
> the
> draft there is the label set object that is very useful in All optical
> networks
> with CI-incapable nodes but lambda conversion is only one of the
> problems
> related to path establishment in such networks. I mean what about OSNR
> and
> non-linear impairments? What about gain variation and power equalization?
> Where
> are covered these topic?
>
> If I can find a path feasible from the lambda continuity point of view
> who
> assure me that I have the needed Q at the end of the all optical path?
>
> Best regards.
>
> ----------------------------------------------------------------
> Diego Caviglia
> Photonic Networks Design and Modelling
> E-mail: diego.caviglia@marconi.com
> Tel: +39 (0) 10 6003 808
> Via A. Negrone 1A 16153 Genoa (Italy)
> http://www.marconi.com