Re: [tcpm] New I-D
MURALI BASHYAM <murali_bashyam@yahoo.com> Wed, 21 February 2007 00:26 UTC
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Date: Tue, 20 Feb 2007 16:26:49 -0800
From: MURALI BASHYAM <murali_bashyam@yahoo.com>
Subject: Re: [tcpm] New I-D
To: mallman@icir.org
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--- Mark Allman <mallman@icir.org> wrote: > > > Well behaved applications usually SHOULD do this, > i > > agree, can't be guaranteed though. Leaving the > problem > > to be addressed by the app, does not ensure > timeliness > > from the point of view that TCP resources such as > > buffers and connections are scarce and by how much > > etc. The scheme lacks robustness if left to the > > application, and for it to be beneficial, ALL > > applications running on a system should be doing > it, > > otherwise there is the weakest link. > > So, let me step back. I should have been more > careful. I think this is > a problem with the draft-not the approach. That is, > I can certainly > understand why a TCP would want to not depend on > apps. But, the text in > the i-d doesn't lead me to that conclusion and I > think it is at very > best dubious in some places. If it is dubious, then we can correct it, and perhaps we need to explain the motivation for that more clearly. > > > At first glance, it does seem like an OS resource > issue, but TCP > > connections can have data backlogged in their send > queues for a > > variety of reasons and for variable amounts of > time, i am not sure how > > a protocol unaware OS based solution can make the > distinction between > > the network causing the backlog transiently, and a > legitimate vs rogue > > receiver causing the backlog etc, i feel that > making it TCP protocol > > specific (something designed only for persist > state) allows for well > > controlled, granular solution(s) and heuristics to > detect specifically > > misbehaving receivers in this scenario. > > We are having a terminology problem here. I meant > "OS" as in the thing > that contains the TCP implementation. I did not > mean that an OS could > blindly reap off resources without understanding > anything about TCP. Okay, we are on the same page :-). > > Let me put it this way ... This seems to me to be a > TCP > **implementation** issue. Why should we need to > standardize this issue > and not other internal resource contention issues? > Why is this anything > but a very local problem that can be handled by the > TCP implementation > in whatever way that implementation chooses? It is an implementation to correct a problem caused by the protocol's REQUIREMENT for a sender to be in an infinite persistence state, thus allowing for abuse by a misbehaving receiver side application (or by a lot of well-behaved receivers). The draft is outlining a solution to the problem (there could be others). The idea in the (informational) draft is to highlight to the group that requirement of the protocol, its consequences and a possible solution. Are you suggesting that any requirements of the protocol specification that lead to a potential denial of service type of scenarios and thus causing internal resource contention, and/or any other network issues are all to be considered 'implementation' ? Shouldn't we look at the requirements of the protocol a little more carefully? > And, then why is the proposed solution the right > one? It does solve the problem it sets out to based on a "total time allowed to be in persist state" type of cap on the duration. Are you implying there could be other behaviours from the receiver that may not be addressed here, such as the receiver opening the window a little and then closing it that fernando mentioned, thus leading to a longer term issue? We need to build heuristics into the solution that can detect this and other types of anomalous receiver behaviour, and take appropriate action. And the heuristics themselves need to be based on a notion of a well behaved receiver in this scenario, to avoid false positives. Murali > > allman > > > > ____________________________________________________________________________________ TV dinner still cooling? Check out "Tonight's Picks" on Yahoo! TV. http://tv.yahoo.com/ _______________________________________________ tcpm mailing list tcpm@ietf.org https://www1.ietf.org/mailman/listinfo/tcpm
- Re: [tcpm] New I-D Mark Allman
- Re: [tcpm] New I-D MURALI BASHYAM
- [tcpm] New I-D Mahesh Jethanandani
- Re: [tcpm] New I-D Wesley Eddy
- Re: [tcpm] New I-D David Malone
- Re: [tcpm] New I-D MURALI BASHYAM
- Re: [tcpm] New I-D (draft-mahesh-persist-timeout-… Fernando Gont
- Re: [tcpm] New I-D (draft-mahesh-persist-timeout-… MURALI BASHYAM
- RE: [tcpm] New I-D (draft-mahesh-persist-timeout-… Anantha Ramaiah (ananth)
- RE: [tcpm] New I-D (draft-mahesh-persist-timeout-… Fernando Gont
- Re: [tcpm] New I-D Mark Allman
- Re: [tcpm] New I-D MURALI BASHYAM
- Re: [tcpm] New I-D Fernando Gont
- Re: [tcpm] New I-D Mark Allman
- Re: [tcpm] New I-D MURALI BASHYAM
- RE: [tcpm] New I-D Caitlin Bestler
- Re: [tcpm] New I-D John Heffner
- Re: [tcpm] New I-D Mahesh Jethanandani
- Re: [tcpm] New I-D John Heffner
- Re: [tcpm] New I-D Mahesh Jethanandani
- [tcpm] New I-D Mahesh Jethanandani