Slides

Case Study: Resilient Backbone Design for IPTV Services

Meeyoung Cha

Gagan Choudhury, Jennifer Yates, Aman Shaikh, Sue Moon

http://www.kaist.ac.kr/index.html

WWW IPTV Workshop 2006 2

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 TVVoD

Regional Network

Regional Network

How can we provide reliable IPTV servicesover the backbone network?

Service Architecture of IPTV


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


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


Design Space

• Reliability

Goal: resilient to single SHO/router/link failures

Mechanisms: Fast-failover + routing protocols

working pathSrc

Dst

Failure

switching

Optical layer SONET protection

Src Dst

working path

protection path

IP layer fast-reroute (FRR)

Failure


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


SHOSHO

BackboneVHO 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


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


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


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)

SHOSHO

L1 network

VHO


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

AccessDual-homed or ring


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


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

Rel

ativ

e co

st

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!

MulticastMulticast

Unicast+

Multicast

Unicast+Multicast

Cost Analysis: Capital Expense 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

-FR

R

Ded

-IP

-Rin

g

Ded

-IP

-Rin

g-F

RR

Int-

IP-H

S

Int-

IP-H

S-F

RR

Int-

IP-R

ing

Int-

IP-R

ing-

FR

R

P2P

-DW

DM

P2P

-DW

DM

-FR

R

Opt

-Sw

itche

d

Rel

ativ

e co

st

accessbackbone

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)


Access Structure vs Traffic LoadsMulticast 3Gbps + Unicast 0Gbps

0.0

1.0

2.0

3.0

4.0

5.0

6.0

Ded

-IP

-HS

Ded

-IP

-HS

-FR

R

Ded

-IP

-Rin

g

Ded

-IP

-Rin

g-F

RR

Int-

IP-H

S

Int-

IP-H

S-F

RR

Int-

IP-R

ing

Int-

IP-R

ing-

FR

R

P2P

-DW

DM

P2P

-DW

DM

-FR

R

Opt

-Sw

itche

d

Rel

ativ

e co

st

access

backbone

Multicast 3Gbps + Unicast 3Gbps

0.0

10.0

20.0

30.0

40.0

Ded

-IP

-HS

Ded

-IP

-HS

-FR

R

Ded

-IP

-Rin

g

Ded

-IP

-Rin

g-F

RR

Int-

IP-H

S

Int-

IP-H

S-F

RR

Int-

IP-R

ing

Int-

IP-R

ing-

FR

R

P2P

-DW

DM

P2P

-DW

DM

-FR

R

Opt

-Sw

itche

d

Rel

ativ

e co

st

access

backbone

Ring access Dual-homed accessmulticast only multicast + VoD

multicast only multicast + VoDRing 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


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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