Case Study: Resilient Backbone Design for IPTV Services

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Case Study Resilient Backbone Design for IPTV
Services

• Meeyoung Cha
• Gagan Choudhury, Jennifer Yates, Aman Shaikh, Sue
  Moon

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Service Architecture of IPTV
SHO
Super Hub Offices (SHO)
Backbone Distribution Network
VHO
How can we provide reliable IPTV servicesover
the backbone network?
Regional Network
Broadcast TV VoD
VHO
Regional Network
Video Hub Office (VHO)
Regional Network
customers
2 SHOs and 40 VHOs across the US
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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

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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

Backbone
Backbone
VHO
Dual-homed
Ring
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Design Space

• Reliability
• Goal resilient to single SHO/router/link
  failures
• Mechanisms Fast-failover routing protocols

Failure
working path
Src
working path
Failure
Dst
Src
Dst
protection path
switching
Optical layer SONET protection
IP layer fast-reroute (FRR)
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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

IP designs
Optical design
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Alt. 1 Integrate With Existing IP Backbone

• 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

SHO
SHO
Backbone
VHO
VHO
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Alt. 2 Dedicated Overlay of Existing IP Backbone

• 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

SHO
SHO
Backbone
VHO
VHO
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Alt. 3 Flat IP (No Backbone)
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
Long haul links
VHO
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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
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Review Design Choices
IP or optical
Technology
Hub-and-spoke or highly meshed
Service layer topology
Link capacity
Dedicated or shared
Access
Fast-failover
Dual-homed or ring
SONET links, fast-reroute, or physically diverse
paths
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Design Instances
Alt.1
Alt.2
Alt.3
Alt.4
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Cost Analysis Capital Expense vs Traffic Loads
MaUb multicast a Gb/s unicast b Gb/s
Multicast Unicast
Multicast
Multicast
Multicast Unicast


Increase in VoD loads has significant impact on
the overall cost. ? Having highly accurate VoD
load forecasts is important!
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Capital Expense Across Designs (Broadcast TV)
Multicast 3Gb/s

• Optical designs are more economical than IP-based
  ones.
• Cost is dominated by access part (except for flat
  IP designs).
• For IP designs, FRR is economical then using
  SONET links.

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Access Structure vs Traffic Loads
multicast only
multicast VoD
Ring access
Dual-homed access
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.
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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