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In-Network Support for VoIP and Multimedia Applications

This overview discusses the support provided for VoIP and multimedia applications within the network, including signaling support, DOS prevention, permission-based networking, in-band media functionality, STUN/TURN support, code delivery, and on-path caching for media streams.

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In-Network Support for VoIP and Multimedia Applications

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

  2. 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 PRESTO (Princeton, NJ)

  3. 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) PRESTO (Princeton, NJ)

  4. SIP trapezoid destination proxy (identified by SIP URI domain) outbound proxy 1st request SIP trapezoid 2nd, 3rd, … request a@foo.com: 128.59.16.1 registrar voice traffic RTP PRESTO (Princeton, NJ)

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

  6. NSIS (Next steps in signaling) PRESTO (Princeton, NJ) Georgios Karagiannis

  7. “RSVP 2.0” unicast-focused, mobility, security keeps soft state sender or receiver-based see RFC 4080 for requirements Layer separation GIST (NTLP) + NSLP1, NSLP2 Separate next-node discovery from signaling UDP and router alerts for discovery TCP/SCTP for signaling NSIS in brief PRESTO (Princeton, NJ)

  8. 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 PRESTO (Princeton, NJ)

  9. 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 SIP proxy & registrar media storage (voicemail, media assets) p2p node generic mapping function PRESTO (Princeton, NJ)

  10. 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 PRESTO (Princeton, NJ)

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

  12. 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 PRESTO (Princeton, NJ)

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