1. 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

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 1. Only tunnel based implementation 1. Fanout limit 6! (ethernet:-( 2. DVMRP limits 2. First native code broke unicast 1. Berkeley report 2. Igmp v1 timers 3. 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