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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. WWW IPTV Workshop SHO Regional Network Regional Network Video Hub Office (VHO) 2 SHOs and 40 VHOs across the US customers Regional Network Regional Network Backbone Distribution Network Super Hub Offices (SHO) VHO VHO Broadcast TV VoD Regional Network Regional Network How can we provide reliable IPTV services over the backbone network? Service Architecture of IPTV
  3. 3. WWW IPTV Workshop IPTV Traffic • Type – Broadcast TV: realtime, 1-3Gb/s – Popular VoD: non-realtime download to VHOs – Niche (esoteric) VoD: realtime, 0-3 Gb/s per VHO • Characteristics – Uni-directional and high-bandwidth – High traffic variability expected for VoD – Multicast for broadcast TV / unicast for VoD
  4. 4. WWW IPTV Workshop Design Space • Technology: layer 1 optical vs. layer 3 IP/MPLS • Service layer topology: hub-and-spoke vs. highly meshed (ring-based) • Access connections: dual-homed vs. ring Dual-homed Ring Backbone Backbone VHO
  5. 5. WWW IPTV Workshop Design Space • Reliability Goal: resilient to single SHO/router/link failures Mechanisms: Fast-failover + routing protocols working path Src Dst Failure switching Optical layer SONET protection Src Dst working path protection path IP layer fast-reroute (FRR) Failure
  6. 6. WWW IPTV Workshop IP designs Optical design Potential IPTV Designs • New dedicated IP backbone for IPTV • Integrating with existing IP backbone • Dedicated overlay over existing IP backbone • Directly inter-connect IP routers (no backbone) • Integrating with existing optical backbone
  7. 7. WWW IPTV Workshop SHO SHO Backbone VHO VHO Support IPTV as multicast application (VoD as unicast) • VHO receives single stream from the nearest SHO • Single network to manage • Backbone links are shared (careful QoS) • Various access connections, fast-failover schemes Alt. 1: Integrate With Existing IP Backbone
  8. 8. WWW IPTV Workshop Backbone SHO SHO VHO VHO Inter-connect common backbone routers with dedicated links • Backbone links are dedicated for IPTV (no QoS) • Overhead for managing overlay • Various access connections, fast-failover schemes Alt. 2: Dedicated Overlay of Existing IP Backbone
  9. 9. WWW IPTV Workshop 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) Alt. 3: Flat IP (No Backbone) SHO SHO VHO VHO
  10. 10. WWW IPTV Workshop 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. WWW IPTV Workshop 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. WWW IPTV Workshop Design Instances Design Layer Link-Capacity Access Type Fast-Failover Int-IP-HS Int-IP-HS-FRR Int-IP-Ring Int-IP-Ring-FRR IP .. .. .. Shared .. .. .. Dual-homed .. Ring .. SONET links Fast re-route SONET links Fast re-route Ded-IP-HS Ded-IP-HS-FRR Ded-IP-Ring Ded-IP-Ring-FRR IP .. .. .. Dedicated .. .. .. Dual-homed .. Ring .. SONET links Fast re-route SONET links Fast re-route P2P-DWDM P2P-DWDM-FRR Optical .. Dedicated .. None .. SONET links Fast re-route Opt-Switched Optical Time-divisioned Dual-homed Disjoint paths Alt.1 Alt.2 Alt.3 Alt.4
  13. 13. WWW IPTV Workshop Cost comparison across traffic demands 0.0 5.0 10.0 15.0 20.0 M1+U0 M2+U0 M3+U0 M1+U1 M2+U2 M3+U3 M1+U0 M2+U0 M3+U0 M1+U1 M2+U2 M3+U3 Relativecost access backbone Int-IP-HS-FRR Opt-Switched Ma+Ub: 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 Cost Analysis: Capital Expense vs Traffic Loads
  14. 14. WWW IPTV Workshop Multicast 3Gbps + Unicast 0Gbps 0.0 1.0 2.0 3.0 4.0 5.0 6.0 Ded-IP-HS Ded-IP-HS-FRR Ded-IP-Ring Ded-IP-Ring-FRR Int-IP-HS Int-IP-HS-FRR Int-IP-Ring Int-IP-Ring-FRR P2P-DWDM P2P-DWDM-FRR Opt-Switched Relativecost access backbone 1. Optical designs are more economical than IP-based ones. 2. Cost is dominated by access part (except for flat IP designs). 3. For IP designs, FRR is economical then using SONET links. Multicast 3Gb/s Capital Expense Across Designs (Broadcast TV)
  15. 15. WWW IPTV Workshop Access Structure vs Traffic Loads Multicast 3Gbps + Unicast 0Gbps 0.0 1.0 2.0 3.0 4.0 5.0 6.0 Ded-IP-HS Ded-IP-HS-FRR Ded-IP-Ring Ded-IP-Ring-FRR Int-IP-HS Int-IP-HS-FRR Int-IP-Ring Int-IP-Ring-FRR P2P-DWDM P2P-DWDM-FRR Opt-Switched Relativecost access backbone Multicast 3Gbps + Unicast 3Gbps 0.0 10.0 20.0 30.0 40.0 Ded-IP-HS Ded-IP-HS-FRR Ded-IP-Ring Ded-IP-Ring-FRR Int-IP-HS Int-IP-HS-FRR Int-IP-Ring Int-IP-Ring-FRR P2P-DWDM P2P-DWDM-FRR Opt-Switched Relativecost access backbone 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-homedRing
  16. 16. WWW IPTV Workshop Conclusion • Explore potential IPTV designs in backbone network • Comparison across different architectural alternatives (use realistic capital cost model) • Design instances generated based on real topologies • Significant benefits of using multicast for broadcast TV • Optical design more economical than IP designs • Ring access attractive for broadcast TV • Dual-homed access attractive for VoD END

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