Multicast Colin Whittaker INEX Members Meeting Tuesday 6 th February 2007

1. Multicast Colin Whittaker INEX Members Meeting Tuesday 6th February 2007

2. All About Me • Senior Network Engineer in Network Development • Previously with HEAnet & Internet Ireland • Responsible for all areas of Network Design and Planning • Responsible for fixing it when the plan doesn’t come together • All opinions are my own and not Magnet Networks

3. Magnet Networks • Magnet Networks part of Columbia Ventures Corporation • Private Investment Company • Telecoms Assets in UK / USA / Australia

4. CVC – Investments Columbia Ventures Corporation – Privately held investment company (Ireland) (Ireland) (United States) (United States) (Australia) (United States) (UK) (United States) (United States) (United States) (United States)

5. Hibernia Atlantic Network

6. Magnet Networks • Magnet Networks started September 2004 • FTTH launched December 2004 • Acquired LEAP in mid 2005 • LLU launch in September 2005 • Acquired Netsource in 2006 • Two Brands – Magnet Entertainment = Residential • –Magnet Business = Corporate

7. Agenda • Tech Primer • Drivers • Challenges

8. Agenda • Drivers • Tech Primer • Challenges

9. IPTV Key Driver • NRENs have deployed already • Large Internal deployments: • Financial and Content Provider segments. • Business Users will demand support in VPN offerings. • IPTV is driving Multicast to the end user • Walled Garden - Magnet / Vodafone & Sky • Public - BBC

10. IPTV key driver • How much bandwidth: • Sky Digital via satellite: MPEG2 4 – 10Mbit/s • SD MPEG 2 @ 4Mbit/s is a tight fit • SD MPEG 4 @ 2 – 3Mbit/s is expected to be the norm • HD MPEG 4 @ 10 – 20Mbit/s is required to maintain quality

11. IPTV Key Driver

12. IPTV Key Driver

13. Agenda • Drivers • Tech Primer • Challenges

14. Unicast • One to One communications • Got us where we are today • Has scaling challenges as number of sessions grows • 10x increase in Users means 10x the traffic volume

15. Unicast

16. Broadcast • One to All • Just like a sprinkler system • Data goes to all Nodes if they want it or not. • Wasted capacity

17. Multicast • Some to Some • One to Many • The Middle ground between Unicast and Broadcast • Replicate as close to the User as possible • Bandwidth only used once and only when needed.

18. Multicast

19. Multicast - ASM • Any Source Mulitcast (1990) • Sources send to multicast groups • Receivers join group and receive from any source • Supports Some to Some and One to Many • Group ID’s are global (limited addresses) • Anyone can DOS your group

20. Multicast - SSM • Source Specific Mulitcast (2000) • Sources send to multicast groups • Receivers join group and source • Group ID’s are based on the source as well as the group • Receivers only see traffic from specific source

21. Multicast - Protocols • PIM-SM (sparse mode – forward on request) • MSDP / Anycast-RP for redundancy • AutoRP & BSR have too many moving parts • MSDP for interdomain support • Multiprotocol BGP for interdomain RPF selection • Well understood toolbox

22. Multicast - Protocols • That’s the Router to Router stuff, now for the LAN • IGMP • v2 and v3 • v3 needed for SSM • IGMP snooping required in switches • IGMP v3 not widely deployed

23. Multicast – Group ID • 224.0.0.0/4 • 224.0.0.0/24 – link local (OSPF) • 239.0.0.0/8 – admin scoped • 233.0.0.0/8 – GLOP – encode as into middle two octets • 232.0.00/8 – SSM range

24. Multicast – MAC addr • Half an OUI reserved for multicast • Steve Deering requested 16 OUIs but only given half of one • 23bits of MAC to contain 28bit of group ID • Leads to 32:1 overlap • Be careful not to overlap with special group id’s

25. Multicast – Tricks • Static Joins • Fast Leave • Bidir • PIM Snooping

26. Channel Zapping • Perceived slowness when changing channel • Single channel join <100msec • For common channels number of hops required is low • GOP much bigger impact. • WM9 GOP = 3sec • Sky / Magnet = .5sec • Iframe caching if >.5sec

27. Agenda • Drivers • Tech Primer • Challenges

28. Access Networks • Easy enough to deploy in Backbone and Data centre • How about to end users

29. DSL • Most DSL users reached via PPPoE / L2TP • Have to replicate at BRAS • Need to send multiple copies into the access network • Cost of bitstream access a concern • Do get benefit of bandwidth saving in the backbone • UK ISPs found this helpful in BBC deployments

30. DSL • Two Solutions • Multiple PVC’s to the customer • One for PPPoE • Second for Video • Run IP all the way to the DSLAM and let it do the replication • Both require Control of the Access Network

31. Wireless • Many wireless devices do not understand multicast. • In many cases a separate copy is sent to each reciever • Video suffers from timing issues

32. Wireless @home • Customers have come to love WiFi • Customers do not want to have to run new cabling • Some solutions available for home networking • 99% of them cannot do multicast • CPE vendors slowly moving to support Multicast

33. Agenda • Drivers • Tech Primer • Challenges

34. P2P • Working around the lack of efficient distribution • Bitorrent • 20GBtye HD movie via Bitorrent • Joost • TV on demand via P2P

35. VOD • TV is our killer app but … • TV is moving to on demand • Sky Plus / Tivo … • VOD traffic will dwarf current traffic

36. Support • It is backwards to “normal” IP • In multicast trouble shooting starts at the receiver • Step by Step back to source • Not as field hardened as unicast • “All Customers TVs stop working after 3 minutes”

37. Further Reading • John Lyons – IP Multicast “The Good, the Bad & the Ugly” • Toerless Eckert – “IP Multicast/Multipoint for IPTV (and beyond)” • Developing IP Multicast – Beau Williamson • Inter-domain IP Multicast – Edwards, Guiliano, Wright • Internet 2

38. Questions ?