Re: Measuring impairments [Was: Updated Draft Liaiosn to Q6/15]
Greg Bernstein <gregb@grotto-networking.com> Tue, 10 March 2009 17:17 UTC
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Date: Tue, 10 Mar 2009 10:17:48 -0700
From: Greg Bernstein <gregb@grotto-networking.com>
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To: Adrian Farrel <adrian@olddog.co.uk>
CC: Giovanni Martinelli <giomarti@cisco.com>, Malcolm Betts <betts01@nortel.com>, "O'Connor, Don" <don.oconnor@us.fujitsu.com>, ccamp@ops.ietf.org
Subject: Re: Measuring impairments [Was: Updated Draft Liaiosn to Q6/15]
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Whoops, sorry Adrian I mis-interpreted your statement: "There is no requirement to measure impairments." To forever exclude the measurement of impairments. Rather than what it says, i.e., "that we don't make you measure impairments". I particularly wanted to ask Q6 about G.697 as a guiding "framework" for measurements. It lists applications, classifies measurement types and gives a short list of some measurable parameters. An aside: In one sense GMPLS already has some optical measurement capabilities via LMP. Also see Seno's new draft draft-seno-ccamp-wson-impairment-compensate-cntl-00.txt that gives another data point for optical measurement applications. Regards Greg Adrian Farrel wrote: > I'm going to try to answer all of the comments about measuring > impairments in one email. > > I'm arguing all of this from an abstract point of view. I want to > "out" in advance of the meeting as much of opinion held in CCAMP. I do > not believe it is valuable to go into the meeting expressing what we > think may be Q6's view. Instead, we need to say what it is people in > CCAMP may want to do. Then we can get Q6 feedback on whether that is > practical and what the concerns are. > > So... > > The ability to measure optical impairments on an active path is > claimed by several vendors. I am not in a position to judge whether > they are successful or not. > > Giovanni reasonably asks "what exactly you mean by *ability to measure*?" > > We are proposing protocol extensions that allow nodes to distribute > information about optical impairments. It is not our business to > define from where this information is gathered. We can observe that > the information might be configured, might be measured during network > provisioning and held static, might be determined by a node applying > some algorithm to configured on pre-measured information, or might be > measured dynamically. So we can choose between: > - optical impairments can be advertised, but cannot be updated > - optical impairments can be advertised, and can be updated > > If we choose the first of these, it seems that we are shutting out > what some people want to be able to do. If we choose the latter, we > are not requiring anyone to update the information they advertise, but > we are allowing this to be done if a node chooses to do so. > > To answer Don specifically, I see no proposal in CCAMP about which > impairments could be measured or how they would be measured. But, to > turn this point around, I do not believe that CCAMP should say "you > must not measure an impairment". As Don says, this is outside our remit. > > Malcolm's suggestion doesn't cut it for me. > By saying "We understand that Q6 currently has no requirement to > measure impairments after the transport equipment is deployed" we miss > the point. The point is not what Q6 requires or does not require, but > is what CCAMP requires. > > So I wonder what is wrong with the statement (in the context of > describing what CCAMP wants to do) that "There is no requirement to > measure impairments." > > Don objected specifically to... >> However, if an implementer chooses to measure impairments >> on their device, this should not be prohibited, and should be >> accommodated. > > How would it be if we defered the practicality of such measurements to > the ITU? We could then write... > > 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 should be > accommodated within GMPLS. > > Cheers, > Adrian > > -- =================================================== Dr Greg Bernstein, Grotto Networking (510) 573-2237
- RE: Measuring impairments [Was: Updated Draft Lia… O'Connor, Don
- Re: Measuring impairments [Was: Updated Draft Lia… Igor Bryskin
- RE: Measuring impairments [Was: Updated Draft Lia… Hernandez-Valencia, Enrique (Enrique)
- Re: Measuring impairments [Was: Updated Draft Lia… Greg Bernstein
- Measuring impairments [Was: Updated Draft Liaiosn… Adrian Farrel