MPTCP Protocol – Status Update draft-ietf-mptcp-multiaddressed-01 Alan Ford IETF 78 – Maastricht

What’s happened since IETF77? draft-ford-mptcp-multiaddressed adopted as WG item Technical additions to -00 Textual changes to -01 2

Differences since IETF77 Editorial changes: – Terminology moved later – Address signalling moved later – Heuristics begun to be separated – Options given more sensible names Explicitly stated fallback at handshake Clarifications of window/DATA_ACK algorithms Clarified separation of subflow- and connection- level processing (also for buffer management) 3

Differences since IETF77 (2) Add Port to ADD_ADDR Path liveness check in REM_ADDR Checksum in DSN_MAP, leading to… Mid-connection fallback mechanism: – Closing affected subflows – If there is only one subflow, it is possible to fall- back without restarting Middlebox discussion improved 4

Detecting Content-Changing Middleboxes Identified as a major issue at IETF77 We don’t want to prevent such boxes – Allowing e.g. address translation is not directly a problem for MPTCP – The problem is with losing DSN_MAP sync So, checksumming allows detection of changes to the content of DSN_MAP content But is this the best way? – It’s relatively expensive, rarely needed, and potentially difficult for offload engines Open to other ideas – Hot off the press: copy last payload byte(s) to DSN_MAP? 5

What now? Open issues: – Subflow policy – Handshake security – hash chains? – Middlebox compatibility Making some components optional? – A lightweight subset of features for specialised, controlled use cases, e.g. data centres Reviews please! 6