[Tsvwg] draft-floyd-tsvwg-cc-alt - Call for WG adoption
Gorry Fairhurst <gorry@erg.abdn.ac.uk> Thu, 08 February 2007 20:23 UTC
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Date: Thu, 08 Feb 2007 20:23:00 +0000
From: Gorry Fairhurst <gorry@erg.abdn.ac.uk>
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Cc: Sally Floyd <floyd@icir.org>, "mallman@icir.org" <mallman@icir.org>
Subject: [Tsvwg] draft-floyd-tsvwg-cc-alt - Call for WG adoption
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I think this is useful, and support its adoption as a working group item intended for BCP publication. It could be worth writing about is the different aspects of this problem space. These are different, and raise issues with different communities. For instance we have views: * traditionally flows need to be controlled, but applications have spanned multiple flows to "modify" the intended behaviour, for good and bad reasons. * some think that end-host traffic need need to be controlled (rather than transport flows) - need to accommodate multi-homed hosts, multi-user systems ... * it's also possible to control traffic through edge routers, some are more concerned about mis-behaving "local" routers and end hosts to protect the service of other local users (e.g. ECN NONCE). It could also be useful to outline background: * End-hosts need to implement congestion-control to behave as responsible systems in the Internet, routers can assist in this role. * Some congestion-control algorithms introduce incentives for end hosts to cheat (not respond appropriately) to attempt to gain a larger share of the capacity along the Internet Path. * Not all paths are equal (in terms of loss, capacity, delay, delay variation, etc), and this can result in very different shares, even though intuitively this may seem unfair or be unexpected by a user. * The security implications of congestion control algorithms also need to be considered, and methods found to mitigate the effects of third-party attacks. * This problem space is orthogonal to RSVP, DS, etc. Best wishes, Gorry Specific comments follow: ---- Page 3: "The second class is algorithms that, while promising, are not deemed safe enough for deployment on the Internet, but are being specified to facilitate investigations via simulation and testbeds." - "Not deemed safe enough" - This sounds like it could be right, but I'd prefer a clearer distinction between the "deemed safe" case, where there is not currently sufficient understanding for IETF to gain consensus that this is safe. ---- Page 3: "describing environments where the protocol is not recommended for deployment even though it may not be unsafe for use" - The double negative makes this harder to read: "may not be unsafe" does this mean "not necessarily safe"? "not necessarily unsafe"? --- Page 3: Section 3: "As noted above, authors are expected to do a well-rounded evaluations" ^ - Omit "s"? ---- Page 3: Section 3: " should not be used as a check-list." - definitive checklist, i.e., it's fine to check these things, but you may need to do more. ---- Page 4: Point (3) "An assessment of proposed algorithms in difficult environments such as paths containing wireless links and paths with reverse-path congestion." - This is not a sentence, perhaps replace the start by: "The proposed algorithms should be assessed in..." - I'd prefer to be concrete on the sort of path characteristics to examine, there is nothing fundamentally dangerous about using "radio" links:-) - so I suspect readers should look at issues such as "corruption loss, higher delay, variable delay, varying capacity, and the implications of BoD" - in short, the sort of things mentioned in RFC3819. ---- Page 5: Point (7) - In point (7) I found it harder to understand what was envisaged to be assessed. I'd have preferred to have some clearer guidance on the sort of things to consider. * The effect of control packet loss /delay/ordering (in hosts, routers). * The effect of loss of state (e.g. due to a protocol restart at a router, or end host). * Returning control information that does not reflect the actual end host state, from an end host or router participating in the protocol. * The transmission of packets designed to trigger an incorrect response by an end host or router participating in the protocol. - IMHO, the effects could more usefully be split between on-path (above) and the other off-path attacks. * Transmission of packets by third parties (that do not have access to the network packets belonging to the flow) with the object of changing the protocol state. * Denial of service attacks against hosts/routers designed to consume resources and reduce resources available for this and/or other protocols. ---- Page 5: Point (9) "is to be carried out." - I'm not a fan of the words "carried out" could "deployed" or something else be used? ---- Section 5 - Not only should " Alternate congestion control schemes should be mindful of such pitfalls, as well." - they MUST of course examine potential security issues that may arise from their use:-) ---- References - I'm sure you've noted QS is now an RFC:-) - An informative reference to SCTP and DCCP may be useful.
- [Tsvwg] draft-floyd-tsvwg-cc-alt - Call for WG ad… Gorry Fairhurst
- Re: [Tsvwg] draft-floyd-tsvwg-cc-alt - Call for W… Sally Floyd