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TCP User Timeout Option (UTO) draft-ietf-tcpm-tcp-uto-04.txt

TCP User Timeout Option (UTO) draft-ietf-tcpm-tcp-uto-04.txt. Lars Eggert (NEC) & Fernando Gont (UTN/FRH) 67 th IETF Meeting, San Diego, California, USA November 5-10, 2006. Overview.

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TCP User Timeout Option (UTO) draft-ietf-tcpm-tcp-uto-04.txt

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  1. TCP User Timeout Option (UTO)draft-ietf-tcpm-tcp-uto-04.txt Lars Eggert (NEC) & Fernando Gont (UTN/FRH) 67th IETF Meeting, San Diego, California, USA November 5-10, 2006

  2. Overview • Peers exchange local, per-connection user timeouts through advisory TCP option and adapt local user timeout accordingly • Motivation: • longer UTO: tolerate longer disconnections • shorter UTO: less TCP state at busy servers • TCP mod, not policy for picking user timeouts • Adopted as WG item at the 61st IETF Meeting (Washington, DC, USA).

  3. Main changes introduced in -03 • Thorough review by Gorry Fairhurst • Rearranged the Introduction • It is now clear from the beginning what the document is about • Removed discussion of SO_RCVTIMEO and SO_SNDTIMEO • these parameters refer to reading/writing from/to socket buffers, rather than waiting for data to be acked, etc. • Clarified that the UTO option is disabled by default. • Could be enabled on a per-connection basis by a socket option, or on a system-wide basis by a toggle (e.g., sysctl) • Enforce lower limit of one RTO • Having a USER TIMEOUT of less than one RTO could be problematic

  4. Main changes introduced in -04 • Added advise that an UTO SHOULD be sent in the first segment sent after the SYN segment that initiated the 3WHS. (as suggested by Caitlin Bestler) • Particularly useful if the end that performed the passive OPEN does not record all the information included in the initial SYN (e.g., SYN cookies). • Clarified the impact on interoperability of not negotiating the option during the connection establishment phase (as suggested by Jamshid Mahdavi) • Potential of 3% of failures (i.e., it is okay in the vast majority of cases) • Those failures result from violating the requirement that TCP MUST ignore unknown options

  5. Changes to be introduced in -05 • Editorial tweaks suggested by Mark Allman • No major changes

  6. Moving forward • We think the draft is ready for WGLC. • Any questions/comments?

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