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  1. 1. Case Study: Resilient Backbone Design for IPTV Services Meeyoung Cha Gagan Choudhury, Jennifer Yates, Aman Shaikh, Sue Moon
  2. 2. Service Architecture of IPTV SHO Regional Network Video Hub Office (VHO) 2 SHOs and 40 VHOs across the US customers Regional Network Backbone Distribution Network Super Hub Offices (SHO) VHO VHO Broadcast TV VoD Regional Network How can we provide reliable IPTV services over the backbone network?
  3. 3. IPTV Traffic <ul><ul><li>Type </li></ul></ul><ul><ul><ul><li>Broadcast TV: realtime, 1-3Gb/s </li></ul></ul></ul><ul><ul><ul><li>Popular VoD: non-realtime download to VHOs </li></ul></ul></ul><ul><ul><ul><li>Niche (esoteric) VoD: realtime, 0-3 Gb/s per VHO </li></ul></ul></ul><ul><ul><li>Characteristics </li></ul></ul><ul><ul><ul><li>Uni-directional and high-bandwidth </li></ul></ul></ul><ul><ul><ul><li>High traffic variability expected for VoD </li></ul></ul></ul><ul><ul><ul><li>Multicast for broadcast TV / unicast for VoD </li></ul></ul></ul>
  4. 4. Design Space <ul><ul><li>Technology: layer 1 optical vs. layer 3 IP/MPLS </li></ul></ul><ul><ul><li>Service layer topology: hub-and-spoke vs. highly meshed (ring-based) </li></ul></ul><ul><ul><li>Access connections: dual-homed vs. ring </li></ul></ul>Dual-homed Ring Backbone Backbone VHO
  5. 5. Design Space <ul><ul><li>Reliability </li></ul></ul><ul><ul><li>Goal: resilient to single SHO/router/link failures </li></ul></ul><ul><ul><li>Mechanisms: Fast-failover + routing protocols </li></ul></ul>working path Src Dst Failure switching Optical layer SONET protection Src Dst working path protection path IP layer fast-reroute (FRR) Failure
  6. 6. Potential IPTV Designs <ul><ul><li>New dedicated IP backbone for IPTV </li></ul></ul><ul><ul><li>Integrating with existing IP backbone </li></ul></ul><ul><ul><li>Dedicated overlay over existing IP backbone </li></ul></ul><ul><ul><li>Directly inter-connect IP routers ( no backbone ) </li></ul></ul><ul><ul><li>Integrating with existing optical backbone </li></ul></ul>IP designs Optical design
  7. 7. Alt. 1: Integrate With Existing IP Backbone SHO SHO Backbone VHO VHO <ul><li>Support IPTV as multicast application (VoD as unicast) </li></ul><ul><ul><li>VHO receives single stream from the nearest SHO </li></ul></ul><ul><ul><li>Single network to manage </li></ul></ul><ul><ul><li>Backbone links are shared (careful QoS) </li></ul></ul><ul><ul><li>Various access connections, fast-failover schemes </li></ul></ul>
  8. 8. Alt. 2: Dedicated Overlay of Existing IP Backbone Backbone SHO SHO VHO VHO <ul><li>Inter-connect common backbone routers with dedicated links </li></ul><ul><ul><li>Backbone links are dedicated for IPTV (no QoS) </li></ul></ul><ul><ul><li>Overhead for managing overlay </li></ul></ul><ul><ul><li>Various access connections, fast-failover schemes </li></ul></ul>
  9. 9. Alt. 3: Flat IP (No Backbone) Long haul links Connect geographically close VHOs into regional rings Inter-connect rings with long haul links Security is higher than using IP backbone No access part Fast-failover Meshed topology (carry “ through ” traffic) SHO SHO VHO VHO
  10. 10. Alt. 4: Integrating with Existing Optical Backbone Multicast capabilities at optical nodes (new technology) SHOs establish multicast trees, VHO receiving single best stream Fast-failover is not yet supported in optical multicasting -> How to find physically diverse paths from two SHOs to each VHO? (NP-hard, integer programming formulation, IEEE GI 06) SHO SHO L1 network VHO
  11. 11. Review: Design Choices Technology Service layer topology Fast-failover Link capacity IP or optical SONET links, fast-reroute, or physically diverse paths Dedicated or shared Hub-and-spoke or highly meshed Access Dual-homed or ring
  12. 12. Design Instances Alt.1 Alt.2 Alt.3 Alt.4 Disjoint paths Dual-homed Time-divisioned Optical Opt-Switched SONET links Fast re-route None .. Dedicated .. Optical .. P2P-DWDM P2P-DWDM-FRR SONET links Fast re-route SONET links Fast re-route Dual-homed .. Ring .. Dedicated .. .. .. IP .. .. .. Ded-IP-HS Ded-IP-HS-FRR Ded-IP-Ring Ded-IP-Ring-FRR SONET links Fast re-route SONET links Fast re-route Dual-homed .. Ring .. Shared .. .. .. IP .. .. .. Int-IP-HS Int-IP-HS-FRR Int-IP-Ring Int-IP-Ring-FRR Fast-Failover Access Type Link-Capacity Layer Design
  13. 13. Cost Analysis: Capital Expense vs Traffic Loads M a +U b : multicast a Gb/s + unicast b Gb/s Increase in VoD loads has significant impact on the overall cost. -> Having highly accurate VoD load forecasts is important! Multicast Multicast Unicast + Multicast Unicast + Multicast
  14. 14. Capital Expense Across Designs (Broadcast TV) <ul><li>Optical designs are more economical than IP-based ones. </li></ul><ul><li>Cost is dominated by access part (except for flat IP designs). </li></ul><ul><li>For IP designs, FRR is economical then using SONET links. </li></ul>Multicast 3Gb/s
  15. 15. Access Structure vs Traffic Loads Ring access Dual-homed access multicast only multicast + VoD multicast only multicast + VoD Ring access is more economical when only multicast traffic is considered. Dual-homed is better for VoD (no through traffic). Flat IP design becomes expensive when VoD considered. Dual-homed Ring
  16. 16. Conclusion <ul><ul><li>Explore potential IPTV designs in backbone network </li></ul></ul><ul><ul><li>Comparison across different architectural alternatives (use realistic capital cost model) </li></ul></ul><ul><ul><li>Design instances generated based on real topologies </li></ul></ul><ul><ul><li>Significant benefits of using multicast for broadcast TV </li></ul></ul><ul><ul><li>Optical design more economical than IP designs </li></ul></ul><ul><ul><li>Ring access attractive for broadcast TV </li></ul></ul><ul><ul><li>Dual-homed access attractive for VoD </li></ul></ul>E ND