Multicast for CATV Distribution Alan Crosswell Columbia University May '05

Contents ● Overview of IP Multicast ● SD/HD Quality Video Bandwidth Requirements ● Decoders & Encoders ● Campus Multicast Routing ● LAN Multicast ● Internet Multicast Routing ● Rights Management ● Licensing Content

Overview of IP Multicast ● For each channel, only one copy of the stream is sent, with routers “forking” it as needed to reach only interested viewers. ● The transmitter sends just one stream no matter if it's 1 or 1000 viewers. ● Compare to unicast streaming (e.g. Real, Quicktime or Windows Media) where your servers and network have to scale up linearly with the number of viewers. ● N.B. “Live” transmission only; not VoD.

Unicast vs. Multicast Multicast Unicast from Internet2 Multicast Workshop

Video Bandwidth Requirements ● Standard Definiton: “D1” 720x480 – MPEG-2: about 5 Mbps – mJPEG (DV): about 30 Mbps ● High Definition: 1080p – MPEG-2: about 270 Mbps ● Typical campus residence network speeds: – Cat 3 Ethernet 10 Mbps – Cat 5+ Ethernet 10/100/1000 Mbps

Decoders ● Set-top box or PC viewer? – Northwestern is using Videofurnace PC viewers – Dartmouth also using Videofurnace. – Cornell is using PC viewer and Amino STB with encryption hardware/software – Is the “TV set” obsolete?

Software Decoders ● Many software viewers available, depending on the encoding – Videofurnace – Cisco IP/TV Viewer (obsolete?) – Vbrick Streamplayer – Videolan Client (VLC; MPEG licensing issues) – Windows Media, Quicktime, etc.

Set Top Decoders ● Amino ● i3 ● 2wire ● Bast Info from Dov Zimring, Occam Networks

Encoders ● What is the source? – Analog: Vbrick, Tandberg, Videofurnace, VLC, etc. – DVB: ● Minerva ● Skystream ● Tut Systems ● Bigband Networks – Stored files (campus TV) ● MPEG->Analog->MPEG or directly use the MPEG from the DVB?

Billing, provisioning, etc. ● Myrio ● Minerva ● Infogate Info from Dov Zimring, Occam Networks

Campus Multicast Routing ● Routing protocols to implement: – PIM-SM - router-to-router – IGMP - host-to-router – MBGP – multicast reachability (used by PIM-SM) – MSDP – multicast source discovery for inter-domain multicast ● These are all widely supported today on modern campus routers (e.g. Cisco, Juniper) ● There are issues on some other vendors' boxes.

LAN Multicast ● Today's biggest problem area for high-bandwidth stream distribution. ● “Old school” broadcast LAN model floods multicast traffic out all switch ports. ● IGMP snooping switches solve this, but: – Be sure they support IGMP version 3 – Invest the time and effort in evaluating competing products. ● See

Internet Multicast Routing ● Not much extra work is required to extend your multicast campus to the multicast Internet. ● A good source/sink for non-commercial TV programming? – ResearchChannel - – Open Student TV Network ● See: –

Rights Management ● IP Multicast does not intrinsically support viewer tracking (which is why it scales so well!). ● How do you track views of premium channels? – Encryption – Application-specific methods for retrieving the encryption key – ?

Licensing Content ● Cornell: Time Warner is peering with the campus network and supplying MPEG-2 streams. A fixed fee per head was negotiated with TW. This service is Cornell-branded. ● Northwestern: ? ● Dartmouth: Adelphia (120 channels)