Re: [ippm] WGLC for draft-ietf-ippm-tcp-throughput-tm-06.txt - part 3
Barry Constantine <Barry.Constantine@jdsu.com> Fri, 17 September 2010 01:08 UTC
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From: Barry Constantine <Barry.Constantine@jdsu.com>
To: "Ruediger.Geib@telekom.de" <Ruediger.Geib@telekom.de>
Date: Thu, 16 Sep 2010 18:02:04 -0700
Thread-Topic: [ippm] WGLC for draft-ietf-ippm-tcp-throughput-tm-06.txt - part 3
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Cc: "ippm@ietf.org" <ippm@ietf.org>
Subject: Re: [ippm] WGLC for draft-ietf-ippm-tcp-throughput-tm-06.txt - part 3
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Hi Rudi, We really appreciate you taking the time to provide really good comments. All have been very insightful, especially this last round. I'll contact you off-list and I would like to schedule time to review all comments. I think we can more efficiently work through these collaboratively (real-time). Thanks again, Barry Principal Member of Technical Staff JDSU Communication Test (formerly Acterna) Emerging Markets and Technology Research One Milestone Center Court Germantown, MD 20876 (W) 240-404-2227 (C) 301-325-7069 -----Original Message----- From: Ruediger.Geib@telekom.de [mailto:Ruediger.Geib@telekom.de] Sent: Thursday, September 16, 2010 10:27 AM To: Barry Constantine Cc: ippm@ietf.org Subject: RE: [ippm] WGLC for draft-ietf-ippm-tcp-throughput-tm-06.txt - part 3 Hi Barry, Part 3 of the comments. Regards, Ruediger ----- Sections 3.1 and 3.2 (MTU, Round Trip and Bandwidth Measurement) The text does not consider the effect of ECMP (IP load sharing). As soon as Flow Aware Transport (FAT) is deployed, the delays will vary depending on the path taken through the network. If the document doesn't consider the application of ECMP with FAT, please state so explicitely. I've missed references to RFC 2681 (RTD) and RFC 5136 (network capacity). On the latter, I'd be interested which of the metrics proposed there would determine "bandwidth" in the sense of your draft. With regard to RTT determination, a reference to RFC 4898 should be included. Section 3.2 ..."Since this methodology requires that RTT be measured during the entire throughput test, the extent by which the RTT varied during the throughput test can be quantified." I don't recall any prior statement that the RTT must/MUST be measured during the entire test and the metrics suggested don't require RTT measurement. If you want to define an additional metric here, please provide more text and a metric definition. The same applies to section 3.2.2: ..."Ideally, the bandwidth test should produce a log output of the bandwidth achieved across the test interval AND the round trip delay. And during the actual TCP level performance measurements (Sections 3.3 - 3.5), the test tool must be able to track round trip time of the TCP connection(s) during the test. Measuring round trip time variation (aka "jitter") provides insight into effects of congestive delay on the sustained throughput achieved for the TCP layer test." In addition to an RTT based metric, here you seem to suggest another metric linking RTT and bandwidth measurement. ----- Section 3.3.1 The diagrams at the end of the section are certainly interesting illustrations, but they may be moved to an appendix. ----- Section 3.3.2 after ..."Dedicated test equipment will generally be required, especially for line rates of GigE and 10 GigE." Should you create a measurement load of more than 10% of any provider backbone link bandwidth on a packet based network, you SHOULD agree your testing activity with the network operating center prior to performing these tests. The same sentence may be added to section 3.4 Traffic management tests, after the same sentence as above. ----- Section 3.3.2 "The TCP throughput test should be run over a a long enough duration to properly exercise network buffers and also characterize performance during different time periods of the day. The results must be logged at the desired interval and the test must record RTT and TCP retransmissions at each interval. This correlation of retransmissions and RTT over the course of the test will clearly identify which portions of the transfer reached TCP Equilbrium state and to what effect increased RTT (congestive effects) may have been the cause of reduced equilibrium performance. Additionally, the TCP Efficiency and TCP Transfer time metrics should be logged in order to further characterize the window size tests." Please clarify and define in your text, which metrics are of true relevance and which are nice to have. You apply strong requirement language here to capture a metric which isn't defined in your document (retransmission to RTT correlation). The metrics you've defined so far "should be performed additionally". This raises the impression that the truly required metrics of this document aren't explicitely defined, I think. ----- Finally, I wonder whether any default settings may be mentioned or approximately validated (you can't always reach them): - max MTU (should be part of a contract - respect layering aspects) - access bandwidth (may well be the bottleneck). - a maximum delay (which may be part of an SLA) - a default TCP window setting (you mention 64KB) ----------That's it--------
- [ippm] WGLC for draft-ietf-ippm-tcp-throughput-tm… Henk Uijterwaal
- Re: [ippm] WGLC for draft-ietf-ippm-tcp-throughpu… Ruediger.Geib
- Re: [ippm] WGLC for draft-ietf-ippm-tcp-throughpu… Barry Constantine
- Re: [ippm] WGLC for draft-ietf-ippm-tcp-throughpu… Ruediger.Geib
- Re: [ippm] WGLC for draft-ietf-ippm-tcp-throughpu… Barry Constantine
- Re: [ippm] WGLC for draft-ietf-ippm-tcp-throughpu… Henk Uijterwaal
- Re: [ippm] WGLC for draft-ietf-ippm-tcp-throughpu… Barry Constantine
- Re: [ippm] WGLC for draft-ietf-ippm-tcp-throughpu… Ruediger.Geib
- Re: [ippm] WGLC for draft-ietf-ippm-tcp-throughpu… Barry Constantine
- Re: [ippm] WGLC for draft-ietf-ippm-tcp-throughpu… Al Morton
- Re: [ippm] WGLC for draft-ietf-ippm-tcp-throughpu… Ruediger.Geib
- Re: [ippm] WGLC for draft-ietf-ippm-tcp-throughpu… Ruediger.Geib
- Re: [ippm] WGLC for draft-ietf-ippm-tcp-throughpu… Barry Constantine
- Re: [ippm] WGLC for draft-ietf-ippm-tcp-throughpu… Ruediger.Geib
- Re: [ippm] WGLC for draft-ietf-ippm-tcp-throughpu… Barry Constantine
- Re: [ippm] End of WGLC for draft-ietf-ippm-tcp-th… Henk Uijterwaal
- Re: [ippm] End of WGLC for draft-ietf-ippm-tcp-th… Barry Constantine
- Re: [ippm] WGLC for draft-ietf-ippm-tcp-throughpu… Al Morton
- Re: [ippm] WGLC for draft-ietf-ippm-tcp-throughpu… Henk Uijterwaal
- Re: [ippm] WGLC for draft-ietf-ippm-tcp-throughpu… Barry Constantine
- Re: [ippm] End of WGLC for draft-ietf-ippm-tcp-th… Barry Constantine
- Re: [ippm] End of WGLC for draft-ietf-ippm-tcp-th… Henk Uijterwaal
- [ippm] WGLC for draft-ietf-ippm-tcp-throughput-tm… Henk Uijterwaal
- Re: [ippm] WGLC for draft-ietf-ippm-tcp-throughpu… Henk Uijterwaal
- [ippm] WGLC for draft-ietf-ippm-reporting-06.txt Henk Uijterwaal
- Re: [ippm] WGLC for draft-ietf-ippm-reporting-06.… Steve Baillargeon
- Re: [ippm] WGLC for draft-ietf-ippm-reporting-06.… Henk Uijterwaal
- [ippm] End of WGLC for draft-ietf-ippm-reporting-… Henk Uijterwaal
- Re: [ippm] WGLC for draft-ietf-ippm-reporting-06.… Steve Baillargeon
- Re: [ippm] End of WGLC for draft-ietf-ippm-report… Henk Uijterwaal
- Re: [ippm] End of WGLC for draft-ietf-ippm-report… Henk Uijterwaal
- [ippm] WGLC draft-ietf-ippm-loss-episode-metrics-… Henk Uijterwaal
- [ippm] WGLC for draft-ietf-ippm-metrictest-03 Henk Uijterwaal
- Re: [ippm] WGLC draft-ietf-ippm-loss-episode-metr… Henk Uijterwaal
- Re: [ippm] WGLC for draft-ietf-ippm-metrictest-03 Henk Uijterwaal
- [ippm] WGLC for draft-ietf-ippm-rt-loss Henk Uijterwaal
- Re: [ippm] WGLC for draft-ietf-ippm-rt-loss Henk Uijterwaal
- [ippm] WGLC for draft-ietf-ippm-testplan-rfc2679-… Henk Uijterwaal
- [ippm] WGLC for draft-ietf-ippm-twamp-value-added… Henk Uijterwaal
- Re: [ippm] WGLC for draft-ietf-ippm-twamp-value-a… Yaakov Stein
- Re: [ippm] WGLC for draft-ietf-ippm-twamp-value-a… steve.baillargeon
- Re: [ippm] WGLC for draft-ietf-ippm-twamp-value-a… Henk Uijterwaal
- Re: [ippm] WGLC for draft-ietf-ippm-twamp-value-a… Al Morton
- Re: [ippm] WGLC for draft-ietf-ippm-twamp-value-a… Steve Baillargeon
- Re: [ippm] WGLC for draft-ietf-ippm-twamp-value-a… Ruediger.Geib
- Re: [ippm] WGLC for draft-ietf-ippm-twamp-value-a… Henk Uijterwaal
- Re: [ippm] WGLC for draft-ietf-ippm-twamp-value-a… Ruediger.Geib
- Re: [ippm] WGLC for draft-ietf-ippm-twamp-value-a… Steve Baillargeon
- Re: [ippm] WGLC for draft-ietf-ippm-twamp-value-a… Wesley Eddy
- Re: [ippm] WGLC for draft-ietf-ippm-twamp-value-a… Al Morton