May 2007 PRESTO (Princeton, NJ) In-network Support for VoIP and Multimedia Applications Henning Schulzrinne Dept. of Computer Science Columbia University

May 2007 PRESTO (Princeton, NJ) Overview signaling support for –DOS prevention –permission-based networking support for in-band media functionality –such as media translation –STUN/TURN support code delivery on-path caching for media streams

May 2007 PRESTO (Princeton, NJ) Separation of signaling and media Router functionality no excuse for merging application signaling and media –mobility (avoid “tromboning”) –logical separation of ISP/IAP and VSP “network neutrality” issues Thus, need media-path specific functions Avoid application-specific traffic admission functions (IMS)

May 2007 PRESTO (Princeton, NJ) SIP trapezoid outbound proxy registrar 1 st request 2 nd, 3 rd, … request voice traffic RTP destination proxy (identified by SIP URI domain)

May 2007 PRESTO (Princeton, NJ) Permission-based networking may I send 100 kb/s? yes, you may, for 10 minutes NSIS (QoS) sets up pinhole NSIS requests are rate-limited possibly with proof-of-work

May 2007 PRESTO (Princeton, NJ) NSIS (Next steps in signaling) Georgios Karagiannis

May 2007 PRESTO (Princeton, NJ) NSIS in brief “RSVP 2.0” –unicast-focused, mobility, security –keeps soft state –sender or receiver-based –see RFC 4080 for requirements Layer separation –GIST (NTLP) + NSLP 1, NSLP 2 –Separate next-node discovery from signaling UDP and router alerts for discovery TCP/SCTP for signaling

May 2007 PRESTO (Princeton, NJ) STUN/TURN support STUN: detect external IP addresses –can embed in NATs (= edge routers) –should be on public Internet and reasonably close (call setup delay) TURN: relay node for “bad” NATs (“symmetric”) –Relays need to be close to media path –typically, operated by access provider

May 2007 PRESTO (Princeton, NJ) Rentable in-network application logic Not really routing or media path-related, but useful –better close to backbone than at edges –need to instantiate hundreds or thousands of clones Example: SIP P2P networks p2p node generic mapping function SIP proxy & registrar media storage (voic , media assets)

May 2007 PRESTO (Princeton, NJ) Code delivery to on-path nodes In progress: Using NSIS to deliver code to on-path nodes NSIS well-suited since not constrained by MTU size –congestion-controlled –soft state and reroute discovery Supports authentication and authorization (Largely) avoids security issues –influence own traffic only –or offer services invoked by others Open issue: near-path and off-path installation

May 2007 PRESTO (Princeton, NJ) On-path caching for media streams cache media server need cacheable protocols, not layer violations

May 2007 PRESTO (Princeton, NJ) Conclusions Opportunities for (semi-)static and dynamic functionality Functionality created by end users, VSPs, ISPs On-path, near-path and off-path –on-path: DOS prevention –near-path: media relaying –off-path: P2P Help with media flow enforcement None of these require programmability, but helpful