Re: Re-Updated Draft Liaison to Q6/15
Greg Bernstein <gregb@grotto-networking.com> Tue, 10 March 2009 17:45 UTC
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Date: Tue, 10 Mar 2009 10:45:56 -0700
From: Greg Bernstein <gregb@grotto-networking.com>
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To: Adrian Farrel <adrian@olddog.co.uk>
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Subject: Re: Re-Updated Draft Liaison to Q6/15
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Looks good to me! Greg Adrian Farrel wrote: > Continuing to try to reach some sort of grudging consensus... > > === > > Dear Peter, > > CCAMP experts are looking forward to our joint meeting with Q6/5 on > March 20th to discuss optical impairments and the control plane > operation of wavelength switched optical networks (WSONs). > > This liaison is to summarise the activity within CCAMP on this subject > so far and to set out our objectives for this work. > > As you will be aware, the GMPLS control plane is designed to provide a > dynamic control plane for a variety of switching technologies. Amongst > these is the "lambda switch capable" data plane where devices are > OEOs, ROADMs, and photonic cross-connects (PXCs). In fact, lambda > switching was the technology that led to the development of GMPLS from > the packet switching MPLS control plane. > > The IETF's CCAMP working group is the design authority for all > extensions to the GMPLS family of protocols. > > The original work on lambda switching networks within CCAMP recognised > that there is a subset of optical networks in which it is possible to > disregard optical impairments and where the number of regeneration > points is high. In these environments, path computation can be > performed on a reachability graph, and lambda conversion can be > performed as necessary within the network. > > As PXCs were introduced into WSONs, it remained the case that optical > impairments could be disregarded by the control plane. Where > necessary, optimal impairment-aware paths could be computed off-line > and supplied to the control plane, leaving the control plane to handle > establishment of connections and recovery after failure. Failure > recovery scenarios might lead to contention for wavelengths or > suboptimal optical paths, but these could be handled by crankback > within the signaling protocol. > > More recent work on WSONs indicates that the proportion of pure > optical devices (ROADMs and PXCs) is increasing. This means that it is > necessary to compute paths that offer end-to-end lambda continuity. > This problem (called the routing and wavelength assignment (RWA) > problem) must be solved, and may be compounded by devices with limited > cross-connect capabilities (for example, with glass-through, a limited > OEO matrix, or restricted port-to-port capabilities). In approaching > this problem it is convenient if there is a common identification > scheme for wavelengths across the whole network (previously, > wavelength identification was a local matter between the nodes at the > ends of each link). To aid with this, the CCAMP working group has > developed > http://www.ietf.org/internet-drafts/draft-ietf-ccamp-gmpls-g-694-lambda-labels-03.txt > > that provides a protocol-independent encoding for wavelengths in a way > that is compliant with G.694. Further work on this problem space can > be seen in the following CCAMP documents: > > "Framework for GMPLS and PCE Control of Wavelength Switched Optical > Networks (WSON)" > http://www.ietf.org/internet-drafts/draft-ietf-ccamp-rwa-wson-framework-01.txt > > > "Routing and Wavelength Assignment Information Model for Wavelength > Switched Optical Networks" > http://www.ietf.org/internet-drafts/draft-ietf-ccamp-rwa-info-01.txt > > "Routing and Wavelength Assignment Information Encoding for Wavelength > Switched Optical Networks" > http://www.ietf.org/internet-drafts/draft-ietf-ccamp-rwa-wson-encode-00.txt > > > CCAMP participants have further identified cases where they believe it > would be helpful to consider optical impairments during the control > plane operation of a WSON. This gives rise to four distinct deployment > scenarios: > > 1. No concern for impairments or lambda continuity > because there is sufficent margin in all impairments. > (Original GMPLS) > 2. No concern for impairments (again because there is > sufficient margin), but lambda continuity is important. > (The RWA problem) > 3. Networks in which it is necessary to consider impairments, > but there is sufficient margin such that approximate > impairment estimation (using "simple" computation of the > accumulation) could be used and still have a high > probability that the optical path would be viable and would > not perturb any existing paths. > 4. Networks in which detailed impairment validation is > necessary to perform a full computation of the accumulation > of impairments including the impact on existing paths. > > > In focusing on the third of these categories, CCAMP intends to base > its work on G.680 and related recommendations with the following > understanding: > - G.680 (et al.) provides the definitions of optical impairments, > optical parameters, and insights into their use > - Where G.680 refers to "single vendor" domains, it does not > mean single manufacturer, but rather "single system integrator". > That is, the equipment is not "plug and play", but has been > tested to interoperate and the network has been planned. > - There is no requirement to measure impairments. > - Many networks are engineered such that configured > impairment values are enough information > - Measuring can often produce ambiguous values > - Equipment to perform measurement may be expensive > However, if an implementer chooses to measure impairments > on their device, and this can be achieved within the mechanisms > and definitions defined by the ITU-T, then this should not be > prohibited by the CCAMP protocol mechanisms, and the > communication of the information collected should be > accommodated within GMPLS. > > With this in mind, CCAMP is looking to Q6/15 to work as a partner in > establishing: > - The complete list of impairments suitable for this type of network, > and the complete list of Recommendations to use as references > - The rules by which such impairments are accumulated along a path. > That is, that CCAMP is looking for the rules by which the end-to- > end impairments of a path may be determined from a knowldedge > of paramters of the path and impairments on the path segments. > - Generic encodings and ranges of values for the impairments > > For reference, some early work on impairment-aware GMPLS is listed > below. This work is not yet adopted as CCAMP work, but is likely to > form the basis of such work once we have discussed the way forward > with Q6/15. > > "A Framework for the Control of Wavelength Switched Optical Networks > (WSON) with Impairments" > http://www.ietf.org/internet-drafts/draft-bernstein-ccamp-wson-impairments-02.txt > > > "Information Model for Impaired Optical Path Validation" > http://www.ietf.org/internet-drafts/draft-bernstein-wson-impairment-info-00.txt > > > Looking forward to a profitable meeting, > Deborah Brungard and Adrian Farrel > CCAMP Working Group Co-Chairs > > -- =================================================== Dr Greg Bernstein, Grotto Networking (510) 573-2237
- RE: Re-Updated Draft Liaison to Q6/15 O'Connor, Don
- RE: Re-Updated Draft Liaison to Q6/15 O'Connor, Don
- RE: Re-Updated Draft Liaison to Q6/15 O'Connor, Don
- Re: Re-Updated Draft Liaison to Q6/15 Adrian Farrel
- RE: Re-Updated Draft Liaison to Q6/15 Malcolm Betts
- Re: Re-Updated Draft Liaison to Q6/15 Dan Li
- Re: Re-Updated Draft Liaison to Q6/15 Giovanni Martinelli
- RE: Re-Updated Draft Liaison to Q6/15 O'Connor, Don
- RE: Re-Updated Draft Liaison to Q6/15 Malcolm Betts
- Re: Re-Updated Draft Liaison to Q6/15 Adrian Farrel
- RE: Re-Updated Draft Liaison to Q6/15 Young Lee
- RE: Re-Updated Draft Liaison to Q6/15 Varma, Eve L (Eve)
- RE: Re-Updated Draft Liaison to Q6/15 Malcolm Betts
- RE: Re-Updated Draft Liaison to Q6/15 Varma, Eve L (Eve)
- Re: Re-Updated Draft Liaison to Q6/15 Adrian Farrel
- RE: Re-Updated Draft Liaison to Q6/15 O'Connor, Don
- Re: Re-Updated Draft Liaison to Q6/15 Greg Bernstein
- Re-Updated Draft Liaison to Q6/15 Adrian Farrel