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Network Architecture (R02) #3 Multicast and Deployment

Network Architecture (R02) #3 Multicast and Deployment. Jon Crowcroft, http://www.cl.cam.ac.uk/~jac22 http://www.cl.cam.ac.uk/teaching/1011/R02. +ve multicast for publisher. Capacity win at sender Some capacity win in network Latency lower potentially For very very popular live content

uriah-cameron
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Network Architecture (R02) #3 Multicast and Deployment

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  1. Network Architecture (R02) #3Multicast and Deployment Jon Crowcroft, http://www.cl.cam.ac.uk/~jac22 http://www.cl.cam.ac.uk/teaching/1011/R02

  2. +ve multicast for publisher • Capacity win at sender • Some capacity win in network • Latency lower potentially • For very very popular live content • Might be only technique • Might steal broadcast tv/radio customers into ISP customer base • Ease of writing applications • Especially collaborative tools (wb/nte etc) for ASM • Except many-to-many reliability very hard:(

  3. -ve for IP Multicast • Problems abounded early on with ASM • Only tunnel based implementation • Fanout limit 6! (ethernet:-( • DVMRP limits • First native code broke unicast • Berkeley report • Igmp v1 timers • PIM route loop!

  4. Time to market • Slowed by bugs • Since then, timeshifting for media (tivo) • New Needs • Share trading still big customer • Urgent (zero day defense) software update • See vigilante for example • Market needs • ISP loses money from multicast:) • Big publisher wins • ISP loses money from CDNs too….

  5. Architectural list of problems • Some are same as for CDN • Except who manages things • Even Inter-domain • E.g. neutrality debate is basically about CDN v. ISP and impact on peering • Security perhaps main pb • Esp. potential DDoS leverage… • multiplier bad

  6. State complexity v. packet forwarding • PGM has same state complexity as SSM • Latches rx nack state on fwd filter • Can have local rtx too • Digital Fountain allows some timeshift • Complex to manage • All single ISP/AS, not interdomain • Interdomain addr allocation not solves really • Traffic breaks peering rules (reverse path:( • So does interdomain P2P and CDN traffic, though

  7. Privacy, Integrity, DDoS prev • Need key distribution • key graph for ASM • Re-key cost (for fwd/reverse secrecy) expensive • Need source management • Need receiver control • Police IGMP join to group per group • Same as CDN, but free there already • Auth is from subscriber to cloud

  8. ASM, SSM, CDN, pub/sub, p2p • Traffic Engineering? • Per source? Per Content? • Energy reduction? • With timeshifting? • V. p2p? • Hybrids? • Server assist P2P? • Multicast assist CDN? • In Net record/timeshift?

  9. general deployment tricks… • Overlay • Underlay • Tunnel • Map/encap

  10. Overlays and Underlays • IP was once an overlay • On x.25 and on PSTN • Then moved down to bare metal • ip on photons too • Overlays are a deployment/evolutionary route • see national academy of science on “looking over the fence at network research)

  11. Other overlay schemes • Mbone, 6bone, abone • RON • Application Layer Multicast • IP on SMS and on Fb! • IP on DNS • Typically tunnel…but • IP in IP overhead • IP on VC - complexity • Circuit setup/teardown • #circuits, qos • routing

  12. Underlays • more revolutionary than overlays • Not many examples - • MPLS, gMPLS • Finesse management/routing problem • 3gpp/cellular • Finesse mobility&billing problem • Other?

  13. Multicast, mobile, multihome • Similar • More than 1 address (at time, in space) • Dynamic - add receiver/delete • Different • Group dynamics possibly fast • Mobility limited by physics • Multihoming slow

  14. Next talk for 25/10/10 The Location/Identity split has been pushed since 8+8 as the solution to mobility (and multihoming) Discuss the various approaches (e.g. 8+8 and LISP) and their various merits and demerits

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