Re: Measuring impairments [Was: Updated Draft Liaiosn to Q6/15]
Igor Bryskin <i_bryskin@yahoo.com> Wed, 11 March 2009 18:23 UTC
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Date: Wed, 11 Mar 2009 11:23:26 -0700
From: Igor Bryskin <i_bryskin@yahoo.com>
Subject: Re: Measuring impairments [Was: Updated Draft Liaiosn to Q6/15]
To: "Hernandez-Valencia, Enrique (Enrique)" <enrique@alcatel-lucent.com>, Adrian Farrel <adrian@olddog.co.uk>, Giovanni Martinelli <giomarti@cisco.com>, Malcolm Betts <betts01@nortel.com>, "O'Connor, Don" <don.oconnor@us.fujitsu.com>
Cc: ccamp@ops.ietf.org
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I agree with Enrique (if, of course, I understood him correctly). We want to advertise things that help to constrain path computation so that resulting paths will likely to be satisfactorily from the impairments point of view. I don't see much value in measurement of optical impairments on existing paths, other than improving the quality of things we advertise and hence future path computation results. Igor ________________________________ From: "Hernandez-Valencia, Enrique (Enrique)" <enrique@alcatel-lucent.com> To: Adrian Farrel <adrian@olddog.co.uk>; Giovanni Martinelli <giomarti@cisco.com>; Malcolm Betts <betts01@nortel.com>; "O'Connor, Don" <don.oconnor@us.fujitsu.com> Cc: ccamp@ops.ietf.org Sent: Tuesday, March 10, 2009 1:31:33 PM Subject: RE: Measuring impairments [Was: Updated Draft Liaiosn to Q6/15] Adrian, If one replaces "optical impairments" for "packet impairments" (e.g., excessive BER, excessive PLR, excessive delay/delay variation) and compares that with what CCAMP currently does for PSC technologies, would that help clarify what CCAMP wants to do for WSON? It would seem the focus of the CCAMP protocol extension would be on advertising budgets/objectives not on actual impairment measurements. Regards, Enrique -----Original Message----- From: owner-ccamp@ops.ietf.org [mailto:owner-ccamp@ops.ietf.org] On Behalf Of Adrian Farrel Sent: Tuesday, March 10, 2009 12:48 PM To: Giovanni Martinelli; Malcolm Betts; O'Connor, Don Cc: ccamp@ops.ietf.org Subject: Measuring impairments [Was: Updated Draft Liaiosn to Q6/15] 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
- 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