17 Jul 2009 20:39
Re: Comment on meth-18.
Scott Poretsky <sporetsky <at> allot.com>
2009-07-17 18:39:17 GMT
2009-07-17 18:39:17 GMT
The magnitude may vary based upon the device under test (DUT) and the Tester. It was agreed by the BMWG to specify units 'seconds' so that any measurement magnitude can be used (including even microseconds). Scott -----Original Message----- From: bmwg-bounces <at> ietf.org [mailto:bmwg-bounces <at> ietf.org] On Behalf Of McLendon, John Sent: Friday, July 17, 2009 2:34 PM To: Kris Michielsen; Al Morton; bmwg <at> ietf.org Subject: Re: [bmwg] Comment on meth-18. Hi Kris, I'm still not sure what "discard" traffic means in terms of a test device. If the test device is monitoring both ports simultaneously (and all of the testers I am knowledgeable about are capable of this), then my understanding of the test scenario is that the test device either detects/causes the switchover, captures the time of the Convergence Event Instant onset, and can then apply the equation once full convergence occurs. If this is correct, then nothing needs to be said about traffic received by the tester on the Preferred Egress Interface unless one wishes to measure the delta between the onset of the Convergence Event Instant and the end of the Convergence Event, i.e. one wants to measure the time between first packet loss and all traffic stopping on the Preferred Egress Interface, i.e. the Ta/Tb/Ta'/Tb'/Ta"/Tb" timestamps in Figure 6. In this case, one might want to state that the tester collects stats on the both interfaces for the entire test, altho' this is implicit in the equations and in Figure 6. I also have one other comment - the current measurement period is reported in seconds. The test devices I am aware of can capture the timestamps with millisecond accuracy (presuming there is a minimum transmission rate of at least two packets per millisecond for each route). One might want to put in a MAY for this. Make sense? J... -----Original Message----- From: Kris Michielsen [mailto:kmichiel <at> cisco.com] Sent: Friday, July 17, 2009 11:46 AM To: McLendon, John; 'Al Morton'; bmwg <at> ietf.org Subject: RE: [bmwg] Comment on meth-18. John, Thanks for reviewing the draft! What do you think of the following suggestion? OLD: For Convergence Events caused by the Tester, such as an IGP cost change, the Tester may start to drop all traffic received from the Preferred Egress Interface at the Convergence Event Instant to achieve the same result. NEW: For Convergence Events caused by the Tester, such as an IGP cost change, the Tester may start to discard all traffic received from the Preferred Egress Interface at the Convergence Event Instant, or may be able to separately observe packets received from the Preferred Egress Interface prior to the Convergence Event Instant, to achieve the same result. Thanks, Kris > -----Original Message----- > From: bmwg-bounces <at> ietf.org [mailto:bmwg-bounces <at> ietf.org] On > Behalf Of McLendon, John > Sent: 16 July 2009 00:00 > To: Al Morton; bmwg <at> ietf.org > Subject: [bmwg] Comment on meth-18. > > Hi all, > I have a comment on the following statement in Sec 4, top of pp. 9, in > meth-18: > > "For Convergence Events caused by the Tester, such as an IGP > cost change, the Tester may start to drop all traffic > received from the Preferred Egress Interface at the > Convergence Event Instant to achieve the same result." > > The word "drop" implies that the test device forwards or > drops traffic. > In my experience, test devices neither forward or drop > traffic. They may generate or analyze traffic, but a test > device dropping traffic doesn't seem helpful to the desired > measurement. Many test devices can bring a link down at the > physical layer. > > J... > > > > -----Original Message----- > From: bmwg-bounces <at> ietf.org [mailto:bmwg-bounces <at> ietf.org] On > Behalf Of Al Morton > Sent: Wednesday, July 15, 2009 3:48 PM > To: bmwg <at> ietf.org > Subject: Re: [bmwg] WGLC: draft-ietf-bmwg-igp-dataplane drafts > > Comments on meth-18, all nits, > Al (mostly as participant) > > At 01:44 PM 7/14/2009, Al Morton wrote: > >...This message begins a Last call on the IGP-Dataplane Convergence > >Time Benchmarking drafts. > > > >http://tools.ietf.org/html/draft-ietf-bmwg-igp-dataplane-conv-term-18 > >http://tools.ietf.org/html/draft-ietf-bmwg-igp-dataplane-conv-meth-18 > >http://tools.ietf.org/html/draft-ietf-bmwg-igp-dataplane-conv-app-17 > > > >The Last Call will end on July 31, 2009. > > > Section 4, top of page 10, > s/At least one condition need to /At least one condition needs to / > > > 5.7. Measurement Accuracy > ... When packet jitter is much less than the convergence > time, it is a negligible source of error and therefor it > will be s/therefor/therefore/ > > 5.9 Tester Capabilities > Add "Also see section 6 for method-specific capabilities." > > 6.1.3. Measurement Accuracy > > TBD > (can't leave this TBD, if there's no obvious material, delete > section ?) > > > Section 7, Reporting Format > > Maximum Packet Delay Threshold seconds > this is called "Forwarding Delay Threshold" in the term doc, right? > pick one for both... > > Section 9, same as terms, use the standard BMWG paragraphs... > > > > > _______________________________________________ > bmwg mailing list > bmwg <at> ietf.org > https://www.ietf.org/mailman/listinfo/bmwg > > <DIV><FONT size="1"> > > E-mail confidentiality. > -------------------------------- > This e-mail contains confidential and / or privileged > information belonging to Spirent Communications plc, its > affiliates and / or subsidiaries. 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