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Modest networking

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  1. Modest networking Joint work with Maria Papadopouli Hannes Tschofenig Xiaoming Fu Jochen Eisl Robert Hancock* Henning Schulzrinne Columbia University MIND Workshop – London, Oct. 7, 2002 Keynote Address (Opinions are the speaker’s and may not be shared by the co-authors…)

  2. Overview • New Realism in networking • Multimodal networking • Some thoughts on QoS • CASP – another attempt at QoS signaling

  3. New realism • Old notion: build it and they will pay • “Don’t want to be just dumb bit carriers’’ • Value add  charge exorbitant fees for shipping special bits • Convergence  all bits are similar • Cheapest bits win (unless monopolies or regulation interfere) • Almost all of networking is/will be a commodity – we should be proud of it!

  4. Cost of networking

  5. Spectrum cost for 3G Generally, license limited to 10-15 years

  6. Multimodal networking • = use multiple types of networks, with transparent movement of information • technical integration (IP)  access/business integration (roaming) • variables: ubiquity, access speed, cost/bit, … • 2G/3G: rely on value of ubiquity immediacy • but: demise of Iridium and other satellite efforts • similar to early wired Internet or some international locations • e.g., Australia

  7. Multimodal networking • expand reach by leveraging mobility • locality of data references • mobile Internet not for general research • Zipf distribution for multimedia content • short movies, MP3s, news, … • newspapers • local information (maps, schedules, traffic radio, weather, tourist information)

  8. Multimedia data access modalities delay bandwidth (peak)

  9. 2G/3G WLAN hotspot + cache Infostation access sharing 7DS A family of access points

  10. 7DS options • Many degrees of cooperation • server to client • only server shares data • no cooperation among clients • fixed and mobile information servers • peer-to-peer • data sharing and query forwarding among peers

  11. Power conservation communication enabled on off time 7DS options Query Forwarding FW query query Host C Host A Host B time Querying active (periodic) passive

  12. Dataholders (%) after 25 min high transmission power P2P Mobile Info Server Fixed Info Server 2

  13. Host A Message relaying with 7DS WLAN Message relaying WAN Host B Host A messages WLAN Gateway

  14. Quality of Service

  15. Why QoS hasn’t happened • need to admit failure – “bandwidth too cheap to meter” • undemocratic: some traffic is more equal than other • dishonest: we only talk about the beneficiaries • reminds you of your mom: no, you can’t have that 10 Mb/s now • socialist: administer scarcity - we like SUVs (or to drive 100 mph)! • “risky scheme”: security exposure – reserve your whole network • niche only: displacement applications (such as telephony) need QoS • touchy-feely: requires cooperation  edge-ISP, transit ISPs, end systems • snake oil: add QoS, lose half your router interface bandwidth

  16. What makes QoS hard • No, it’s not RSVP scaling • network has become harder to evolve: • network address translation • firewalls • high packetization overhead (VPNs, IPv6) • nobody can be trusted • to be useful, has to be nearly universally supported (“no, you can’t make calls to AS 123”) • network QoS vs. business class model: “coach is empty, please refund fare” • almost all the time, reserved traffic gets same delay as best effort • applications will switch QoS classes

  17. What makes QoS hard • currently, the ISP interface is IP and BGP – adding a third one is a big deal • trust model  ISP or cash model • payment model completely unclear for peering • new Internet service model: TCP client (inside) – server (outside) • exception: peer-to-peer on college campuses • network to host: you first, no, you first

  18. What is QoS, really? • Network transparency • no loss (< 1%) • very few delay spikes (< 1%) • close to propagation delay • anything else is too hard to explain to users! • QoS is just a facet of network reliability • consistent 5% packet loss is much better than 5% probability that network is unavailable for seconds • users are willing to pay for availability • traditional QoS may help availability during outage periods • e.g., MCI/UUnet breakdown 10/3/02 • DOS attacks • failure of load distribution links

  19. CASP = Cross-Application Signaling Protocol • RSVP is being used for lots of things beyond flow setup: RSVP TE, midcom, … • Complex and monolithic • multicast support  • multiple reservation styles • killer reservations and error handling • receiver-orientation only • non-RSVP region handling • interface complexity (LIH) • fairly closely ties QoS to RSVP • hard to extract generic signaling protocols •  CASP as modular signaling protocol • currently a proposal for IETF NSIS group

  20. What is CASP? • Genericsignalingservice • establishes state along path of data • one sender, typically one receiver • can be multiple receivers  multicast • can be used for QoS per-flow or per-class reservation • also: firewall setup, TE, programmable networks, configuration, topology exploration, … • avoid restricting users of protocol (and religious arguments): • sender vs. receiver orientation • more or less closely tied to data path • router-by-router • network (AS)

  21. CASP network model – on-path selective CASP chain • CASP nodes form CASP chain • not every node processes all client protocols: • non-CASP node: regular router • omnivorous: processes all CASP messages • selective: bypassed by CASP messages with unknown client protocols QoS QoS QoS midcom omnivorous

  22. CASP network model – out-of-path Bandwidth broker NAC • Also route network-by-network • can combine router-by-router with out-of-path messaging CASP AS15465 AS17 AS 1249 data

  23. client layer does the real work: reserve resources open firewall ports … messaging layer: establishes and tears down state negotiates features and capabilities transport layer: reliable transport CASP protocol structure client layer (C) scout protocol CASP messaging layer (M) messaging layer (M) transport layer (T) UDP IP router alert

  24. Next-hop discovery • Next-in-path service • enhanced routing protocols  distribute information about node capabilities in OSPF • routing protocol with probing • service discovery, e.g., SLP • first hop, e.g., router advertisements • DHCP • scout protocol • Next AS service • touch down once per autonomous system (AS) • new DNS name space:, e.g., • use new DNS NAPTR and SRV for lookup • similar to SIP approach

  25. Mobility and route changes • avoids session identification by end point addresses • avoid use of traffic selector as session identifier • remove dead branch DEL (B=2) discovers new route on refresh B=1 ADD B=2

  26. Conclusion • Until wireless bits are too cheap to meter, try hiding lack of universal high bit density from user • QoS is a reliability mechanism • CASP as a new signaling platform