Re: [tcpm] initial RTO (was Re: Tuning TCP parameters for the 21st century)
Mark Allman <mallman@icir.org> Thu, 30 July 2009 11:41 UTC
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From: Mark Allman <mallman@icir.org>
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Subject: Re: [tcpm] initial RTO (was Re: Tuning TCP parameters for the 21st century)
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> It's necessary to disambiguate which ACK is for which SYN - i.e. if > you have a _very_ long-delay path, you might send out three SYNs > before an ACK to the first SYN comes in. But it appears at the time to > be an ACK to the third SYN, with other responses lost in transit. So > SYN timestamps really are necessary to disambiguate in this > situation. I can see a cascading sequence where the first ACK comes in > just after say the fifth SYN goes out, and it's immediately necessary > to bump the RTO up to tens of seconds. Sure. I guess Jerry and I are talking about the case where with exceedingly high probability the RTT is covered by the current 3sec RTO and the vast majority of the connections have an RTT of less than 1sec. (So, say, 99.99999% < 3sec and 98% < 1sec.) So, how then do we use 1sec for the common case, but still reasonably accommodate the fraction that have RTTs > 1sec but < 3sec? Would it be nice to keep pushing and accommodate connections with even larger RTTs? Ideally, yeah. But, I am not sure imposing timestamps or other mechanisms on everyone to deal with that case is useful. At some point you have to engineer your edge case for what it is. allman
- [tcpm] Tuning TCP parameters for the 21st century Jerry Chu
- Re: [tcpm] Tuning TCP parameters for the 21st cen… Erik Nordmark
- Re: [tcpm] Tuning TCP parameters for the 21st cen… Joe Touch
- Re: [tcpm] Tuning TCP parameters for the 21st cen… Jerry Chu
- Re: [tcpm] Tuning TCP parameters for the 21st cen… Joe Touch
- Re: [tcpm] Tuning TCP parameters for the 21st cen… Jerry Chu
- Re: [tcpm] Tuning TCP parameters for the 21st cen… Jerry Chu
- Re: [tcpm] Tuning TCP parameters for the 21st cen… Joe Touch
- Re: [tcpm] Tuning TCP parameters for the 21st cen… Michael Scharf
- Re: [tcpm] Tuning TCP parameters for the 21st cen… Joe Touch
- Re: [tcpm] Tuning TCP parameters for the 21st cen… michawe
- Re: [tcpm] Tuning TCP parameters for the 21st cen… Joe Touch
- Re: [tcpm] Tuning TCP parameters for the 21st cen… Jerry Chu
- Re: [tcpm] Tuning TCP parameters for the 21st cen… Rui Paulo
- Re: [tcpm] Tuning TCP parameters for the 21st cen… Jerry Chu
- Re: [tcpm] Tuning TCP parameters for the 21st cen… Jerry Chu
- Re: [tcpm] Tuning TCP parameters for the 21st cen… Joe Touch
- Re: [tcpm] Tuning TCP parameters for the 21st cen… Michael Welzl
- Re: [tcpm] Tuning TCP parameters for the 21st cen… Jerry Chu
- Re: [tcpm] Tuning TCP parameters for the 21st cen… Jerry Chu
- Re: [tcpm] Tuning TCP parameters for the 21st cen… Michael Welzl
- [tcpm] initial RTO (was Re: Tuning TCP parameters… Mark Allman
- Re: [tcpm] initial RTO (was Re: Tuning TCP parame… Jerry Chu
- Re: [tcpm] initial RTO (was Re: Tuning TCP parame… Mark Allman
- Re: [tcpm] initial RTO (was Re: Tuning TCP parame… Jerry Chu
- Re: [tcpm] initial RTO (was Re: Tuning TCP parame… Mark Allman
- Re: [tcpm] initial RTO (was Re: Tuning TCP parame… L.Wood
- Re: [tcpm] initial RTO (was Re: Tuning TCP parame… Mark Allman
- Re: [tcpm] initial RTO (was Re: Tuning TCP parame… L.Wood
- Re: [tcpm] initial RTO (was Re: Tuning TCP parame… Jerry Chu
- Re: [tcpm] initial RTO (was Re: Tuning TCP parame… Jerry Chu
- Re: [tcpm] initial RTO (was Re: Tuning TCP parame… Mark Allman
- Re: [tcpm] initial RTO (was Re: Tuning TCP parame… Jerry Chu
- Re: [tcpm] initial RTO (was Re: Tuning TCP parame… Mark Allman
- Re: [tcpm] initial RTO (was Re: Tuning TCP parame… Jerry Chu