[tcpm] rfc2581bis [2]: limiting cwnd inflation
Mark Allman <mallman@icir.org> Tue, 13 February 2007 15:06 UTC
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From: Mark Allman <mallman@icir.org>
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Subject: [tcpm] rfc2581bis [2]: limiting cwnd inflation
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Reminder, the draft should pop out of the usual places soon, but until then you can slurp a copy from: http://www.icir.org/mallman/papers/draft-ietf-tcpm-rfc2581bis-02.txt The second issue ... We added a note to step 4 of the fast retransmit/recovery procedure: 4. For each additional duplicate ACK received (after the third), cwnd MUST be incremented by SMSS. This artificially inflates the congestion window in order to reflect the additional segment that has left the network. Note: [SCWA99] discusses a receiver-based attack whereby many bogus duplicate ACKs are sent to the data sender in order to artificially inflate cwnd and cause a higher than appropriate sending rate to be used. A TCP MAY therefore limit the number of times cwnd is artificially inflated during loss recovery to the number of outstanding segments (or, an approximation thereof). That is, we explicitly allow a TCP to limit the number of dupacks that are acceptable during fast recovery to prevent an attack such as discussed in [SCWA99]. Note that (1) this is more conservative than the algorithm in 2581 and so implicitly allowed already (that is, we are just calling attention to this) and (2) we are not trying to mandate this behavior, just noting that it might be useful. Comments would be appreciated. Thanks, allman
- Re: [tcpm] rfc2581bis [2]: limiting cwnd inflation Mark Allman
- [tcpm] rfc2581bis [2]: limiting cwnd inflation Mark Allman
- RE: [tcpm] rfc2581bis [2]: limiting cwnd inflation Anantha Ramaiah (ananth)
- RE: [tcpm] rfc2581bis [2]: limiting cwnd inflation Anantha Ramaiah (ananth)
- Re: [tcpm] rfc2581bis [2]: limiting cwnd inflation Mark Allman