[Tsvwg] AD review of draft-ietf-tsvwg-quickstart-05
Lars Eggert <lars.eggert@netlab.nec.de> Wed, 02 August 2006 14:18 UTC
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From: Lars Eggert <lars.eggert@netlab.nec.de>
Date: Wed, 02 Aug 2006 16:17:54 +0200
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Subject: [Tsvwg] AD review of draft-ietf-tsvwg-quickstart-05
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Hi, find my review of draft-ietf-tsvwg-quickstart-05 below. I didn't find any major technical issues, it's mostly small nits. One overall meta-comment, however, is that the document mixes specification (description of the mechanism and protocols) and applicability statements (discussion of behavior, effects, issues, plus long appendices discussing related work, design options not taken, a rebuttal to a review, etc.) This makes it difficult for the reader to extract the mandatory-to-implement pieces out of the overall work. For a Standards Track document, I'd require that this be addressed, probably by refactoring the document into multiple smaller and more focused ones. Since this is going for Experimental, I'm not going to require this, but still would like to strongly suggest that the authors discuss whether presenting the large body of work in a small number of more focused documents (maybe: architecture, IP-layer extension specification, TCP extension specification, applicability statement) may not be more readable. Lars INTRODUCTION, paragraph 0: Document uses "Quick-Start", "Quick Start" and "QuickStart" - choose one. Section 1., paragraph 2: > However, in the case of moderate-sized transfers the connection > might carry out its entire transfer in the slow-start phase, taking > many round-trip times, where one or two RTTs might have been > appropriate in the current network conditions. I think this should read "...where one or two RTTs might have been sufficient when using the currently available bandwidth along the path." Section 2., paragraph 5: > * Any new mechanism must be incrementally deployable, and might not > be supported by all of the routers and/or end-hosts. Thus, any new > mechanism must be able to accommodate non-supporting routers or end- > hosts without disturbing the current Internet semantics. We note > that while Quick-Start is incrementally deployable in this sense, a > Quick-Start request can not be approved for a particular connection Nit: s/can not/cannot/ Section 3.4., paragraph 1: > the received Rate Request was in fact less than K. This version of > the nonce is based on a proposal from Guohan Lu [L05]. Initial > versions of this document contained an eight-bit QS Nonce, and > subsequent versions discussed the possibility of a four-bit QS > Nonce. May want to move mention of [L05] to the acknowledgment section, and remove second part of the paragraph starting with "This version of the nonce..." Section 3.4., paragraph 10: > An additional requirement is that the receiver can not be able to Nit: s/can not/cannot/ Section 4., paragraph 2: > section.) When used for initial start-up, the Quick-Start request > packet can be either the SYN or SYN/ACK packet, as described above. Wasn't really described anywhere above, just part of the examples. Section 4., paragraph 4: > If the acknowledging packet does not contain a Quick-Start Response, > or contains a Quick-Start Response with the wrong value for the TTL > Diff or the QS Nonce, then host A MUST assume that its Quick- Start > request failed. In this case, host A sends a Report of Approved > Rate with a Rate Report of zero, and uses TCP's default congestion > control procedure. For initial start-up, host A uses the default > initial congestion window [RFC2581]. Why can't it use large initial windows still? Section 4., paragraph 5: > In > order to use Quick-Start, the TCP host MUST use rate-based pacing to > transmit Quick-Start packets at the rate indicated in the Quick- > Start Response, at the level of granularity possible by the sending > host. Might want to cite http://www.isi.edu/~johnh/PAPERS/Visweswaraiah97b.html for rate-based pacing. Section 4.4., paragraph 1: > In addition, if the received Rate Request > is K, then the the rightmost 2K bits of the QS Nonce must match Nit: s/the the/the/ Section 4.6.1., paragraph 0: 4.6.1. Interactions with Path MTU Discovery Since draft-ietf-pmtud-method is about to be IETF-last-called, it would be good to discuss here how QuickStart interacts with the new-style PMTUD, in addition to how it interacts with the old PMTUD method. Section 4.6.1., paragraph 3: > If the sender knows the Path MTU when the initial window is sent > (e.g., from a PMTUD cache or from some other IETF-approved method), > then the sender should use that MTU for segments in the initial > window. "SHOULD use that MTU"? Section 4.7., paragraph 6: > (2) Response if Quick-Start packets are dropped: Nit: s/(2)/(3)/ Section 10.3., paragraph 1: > Because of possible problems discussed above concerning using Quick- > Start over some network paths and the security issues discussed in > section 11 , the most realistic initial deployment of Quick-Start Nit: s/11 ,/11,/ Section 12., paragraph 0: 12. IANA Considerations Please check draft-narten-iana-considerations-rfc2434bis, Section 5.1 on how to write this section. Section 14., paragraph 3: A. Related Work Since this is already a pretty long draft, is there value in having this discussion of related work included here? Section 14., paragraph 36: B. Design Decisions Since this is already a pretty long draft, is there value in having this discussion included here? Section 14., paragraph 102: C. Quick-Start with DCCP Should probably become its own document in the future - needed here? Section 14., paragraph 113: D. Possible Router Algorithm Is this redundant, given there is Section 3.3? Section 14., paragraph 132: F. Feedback from Bob Briscoe Not sure if a rebuttal to a review is useful to publish as an appendix. Section 14., paragraph 176: > [2401bis] S. Kent and K. Seo, Security Architecture for the Internet > Protocol, internet-draft draft-ietf-ipsec-rfc2401bis-06.txt, work- > in-progress, March 2005. is RFC4301 Section 14., paragraph 178: > [2402bis] S. Kent, IP Authentication Header, internet-draft draft- > ietf-ipsec-rfc2402bis-11.txt work-in-progress, March 2005. is RFC4302 Section 14., paragraph 184: > [RFC2960] R. Stewart, et. al. Stream Control Transmission Protocol. > RFC 2960, October 2000. Nit: s/et./et/ Section 14., paragraph 199: > [BJS05] Briscoe, B., Jacquet, A., and A. Salvatori, "Re-ECN: Adding > Accountability for Causing Congestion to TCP/IP", internet-draft > draft-briscoe-tsvwg-re-ecn-tcp-00.txt, work-in-progress, October > 2005. is at -02 Section 14., paragraph 209: > [KHF05] E. Kohler, M. Handley, and S. Floyd, Datagram Congestion > Control Protocol (DCCP), internet draft draft-ietf-dccp- spec-11.txt, > work in progress, March 2005. is RFC4340 Section 14., paragraph 223: > [SGF05] Singh, M., Guha, S., and P. Francis, "Utilizing spare > network bandwidth to improve TCP performance", ACM SIGCOMM 2005 Work > in Progress session , August 2005, Nit: s/session ,/session,/ -- Lars Eggert NEC Network Laboratories
- [Tsvwg] AD review of draft-ietf-tsvwg-quickstart-… Lars Eggert
- Re: [Tsvwg] AD review of draft-ietf-tsvwg-quickst… Sally Floyd
- Re: [Tsvwg] AD review of draft-ietf-tsvwg-quickst… Erblichs
- Re: [Tsvwg] AD review of draft-ietf-tsvwg-quickst… Sally Floyd
- Re: [Tsvwg] AD review of draft-ietf-tsvwg-quickst… Bob Briscoe
- Re: [Tsvwg] AD review of draft-ietf-tsvwg-quickst… Sally Floyd