1. PPSP NAT traversal Lichun Li, Jun Wang, Yu Meng {li.lichun1, wang.jun17,meng.yu}@zte.com.cn draft-li-ppsp-nat-traversal-00

2. Terminology STUN/TURN/proxy/relay peer special PPSP peers providing NAT traversal services User nodes or super nodes deployed by the operator STUN peer – Provides STUN service TURN peer – provides relay service in TURN layer – application agnostic relay Proxy peer – relays PPSP message in PPSP layer – Application specific relay (similar to HTTP/SIP proxy, RELOAD peer) Relay peer – A peer providing relay services: a TURN peer, proxy peer or both. Candidate (from ICE RFC5245) – A transport address that is a potential point of contact for receipt of media. Relayed candidate (from ICE) – A peer’s relayed candidate is the address assigned by its TURN server. Proxy candidate – A peer's proxy candidate is the address of its serving proxy peer. 2

3. PPSP network applying NAT traversal solution Peers may gather reflexive/relayed candidates from STUN/TURN servers Peer list contains candidates and peer ID. 3

4. NAT traversal One-direction connectivity checks are PPSP checks or modified ICE checks – Standard ICE connectivity checks require exchanging ICE parameters Optional ICE process for optimizing communication path 4

5. Standard ICE 5 Peers must exchange ICE parameters with offer/answer model ICE check connectivity with STUN binding messages. – user name fragments and passwords exchanged in offer/answer phase Testing relayed candidate – Add permission in TURN server

6. One-direction ICE connectivity check without offer/answer Authentication change – Don’t use STUN name fragment. Put the whole STUN user name & password in peer list – A adds permission in B’s serving TURN peer by some means 6

7. One-direction PPSP connectivity check Compared with ICE connectivity check, PPSP connectivity check – can use PPSP’s own authentication method, and avoid the STUN/TURN authentication problem – uses PPSP messages instead of STUN binding messages – uses proxy candidate instead of relayed candidate 7

8. Media Traversal of NAT ICE parameters can be exchanged with PPSP messages MediaAttach messages may be relayed by proxy/TURN peer 8

9. Requirements for PPSP Tracker protocol MUST – allow STUN/TURN/proxy ability report – allow STUN/TURN/proxy peer list query – allow reporting candidates – contain candidates in peer list – allow tracker instructing peer to work in NAT-traversal/no-NAT- traversal mode? Peer protocol MUST – allow exchanging ICE parameters – contain candidates in peer list If one-direction connectivity is checked – in ICE layer, we need to modify ICE and TURN. – In PPSP layer, peer protocol MUST allow connectivity check in PPSP layer allow PPSP message relay allow obtaining and maintaining proxy candidate allow STUN/TURN/proxy peer list exchange 9

10. Next Steps Get more comments Refine NAT traversal solution Design NAT-traversal required messages in details 10

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