MPTCP – MULTIPATH TCP WG meeting #3 July 27 th & 29 th 2010 Maastricht, ietf-78 Philip Eardley Yoshifumi Nishida

Scribes Jabber Please include “-mptcp-” in your draft names Please say your name Slides at erials.html erials.html

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Agenda Tuesday Auditorium 2 Options vs payload discussion Objective: To come to WG consensus on which approach MPTCP will use (options or payload). Thursday Auditorium 1 Objectives: Placeholder to confirm /continue options vs payload decision (if further discussion time is needed Brief Report back from Implementors workshop Progress to fulfil our Milestone (Aug 2010) - Submit to IESG architectural guidelines and security threat analysis as informational RFC(s) Progress on other WG drafts Consensus to create WG draft(s) for Milestones on extended API and applications considerations. Interim audio meeting If we run out of time

Today’s agenda – Agenda bash, Intro, note-takers (5mins) Brief Report back from Implementors workshop (5mins) Consensus call on Options vs Payload (10mins) Progress to fulfil our Milestone (Aug 2010) –Security threats – Marcelo Bagnulo (5mins) –Architecture – Alan Ford (5mins) Progress on other WG drafts –draft-ietf-mptcp-multiaddressed (10mins, Alan Ford) –draft-ietf-mptcp-congestion (5mins, Costin Raicu) Consensus to create WG draft(s) for Milestones on extended API and application considerations. –API and application considerations (10mins, Michael Scharf) Other documents –Alert about work on interface between multipathing and address selection (5mins, Aleksi Suhonen)

Implementors workshop Saturday 24 th July, Maastricht _workshop _workshop Objective: to help make Multipath TCP real –to get it implemented in many operating systems and to get it used by key applications. –Bring together: people who’d use MPTCP, OS implementors & WG protocol designers Discuss the use cases for Multipath TCP Discuss Multipath TCP & OSes. Organised under the auspices of the MPTCP working group, but is not a formal WG meeting ~ 25 participants

Implementors workshop Use case #1: Mobiles –Energy saving by aggressively shifting to energy efficient radio –Impact on advanced API? –Resilience now seen as less important Use case #2: Data centres –Everything under operator control May simplify some MPTCP protocol aspects –MPTCP naturally puts traffic on path with capacity –Plenty of research issues

Implementors workshop OS discussions Linux implementation on-going – BSD effort would be great On-going considerations –Eg more often out of order Ability to use hardware accelerations –Think of NIC as a middlebox

Implementors workshop Worth doing again Remote participation not easy Bay area workshop suggested

Consensus call MPTCP needs to signal control data; how? Extensive discussions in Anaheim, on Tuesday and on the list We agreed to reach consensus whether to go for Options or Payload, by the end of Maastricht –To be confirmed on the list #1: Use a TCP option (for all signalling) #2: Use TLV encoding in payload (for at least some signalling)

Today’s agenda – Brief Report back from Implementors workshop Consensus call on Options vs Payload Progress to fulfil our Milestone (Aug 2010) –Security threats – Marcelo Bagnulo (5mins) –Architecture – Alan Ford (5mins) Progress on other WG drafts –draft-ietf-mptcp-multiaddressed (10mins, Alan Ford) –draft-ietf-mptcp-congestion (5mins, Costin Raicu) Consensus to create WG draft(s) for Milestones on extended API and application considerations. –API and application considerations (10mins, Michael Scharf) Other documents –Alert about work on interface between multipathing and address selection (2mins, Aleksi Suhonen)

Background MPTCP needs to signal control data – how? –Use a TCP option Traditional TCP method –Use TLV encoding in payload No space issues Note: if control data is lost, need to detect & fallback to regular TCP –If unknown Options get dropped by a typical middlebox, then signalling using Options is difficult –Measurement info about this (next presentations) We agreed to reach consensus whether to go for Options or Payload, by the end of Maastricht

Corridor meeting Discussed Options vs Payload for signalling about: 1.MPTCP-capable 2.Adding new paths 3.Data sequence mapping 4.Data ACKs Context for later discussions

Corridor meeting - conclusions Discussed Options vs Payload for signalling about: 1.MPTCP-capable Agree best to use TCP Option on SYN 2.Adding new paths Agree best to use Option 3.Data sequence mapping Agree not much difference between Options and Payload. Agree Payload may have slight performance benefit 4.Data ACKs Agree Data ACKs are needed (>= SHOULD), otherwise (potentially substantial) inefficiency Agree Payload can suffer from head-of-line-blocking -> performance penalty