1. MPTCP proxy mechanisms (draft-wei-mptcp-proxy-mechanism-00)
IETF 90 Toronto, Canada
Xinpeng Wei

2. Why MPTCP proxy is needed？ --An example
TCP server
path#1
Internet
MPTCP host
path#2
Currently most of servers on Internet are TCP server, and this situation will significantly prevent MPTCP-capable hosts to fully benefit from MPTCP.

3. Basic concept of MPTCP proxy
mapping
MPTCP connection
TCP connection
MPTCP host
MPTCP
TCP
TCP host
proxy

4. How could MPTCP proxy be deployed?
Internet
MPTCP host
TCP server
MPTCP
proxy
UGW
MPTCP proxy: off-path model
Internet
MPTCP host
TCP server
MPTCP
proxy
UGW
MPTCP proxy: on-path model

5. Mechanisms for off-path MPTCP proxy
①initial sub-flow setup with server
TCP server
②inspect MPTCP initial sub-flow
Internet
MPTCP
proxy
④set up TCP connection
MPTCP host
③inform the existence of proxy to host, and set up sub-flow between host and proxy. (ADD_ADDR(proxy IP))
⑤set up new sub-flow with proxy.

6. Mechanisms for on-path MPTCP proxy
①initial sub-flow setup with server
TCP server
②inspect MPTCP initial sub-flow
Internet
④set up TCP connection
MPTCP host
MPTCP
proxy
③set up sub-flow between host and proxy.
⑥inspect new sub-flow setup and set up sub-flow instead of server.
⑤setup new sub-flow with server

7. Extension to MPTCP protocol
A new flag 'P' in MPTCP MP_CAPABLE option needs to be defined, refer to RFC 6824, Section 3.1. This flag is used by proxy to inform MPTCP capable host the existence of proxy.