Transcript Infrastructure Design for IPTV Services

Infrastructure Design
for IPTV Services
IPTV Asia
November 8-9, 2006
Grand Copthorne Waterfront Hotel, Singapore
Sue Moon
Joint Work with
Meeyoung Cha (KAIST)
W. Art Chaovalitwongse (Rutgers/DIMACS)
Gagan Choudhury, Zihui Ge, Aman Shaikh, Jenniver Yates (AT&T)
Push behind IPTV

TV service over IP
 Replacement of TV distribution networks
 Core service of “Triple Play” (voice, data, video) and
“Quadruple Play” (+wireless/mobile)

Evolution Path
 Controversy over distinction between broadcasting and


communication
Bundled vs blended services
As seen here so far! 
2
Technical Challenges of IPTV

Distribution network
 WAN, MAN, and access technologies
Resilient design required
 QoS guarantee
Same level of quality as today’s TV offers

Platform
 Standardizations: AV coding, EPG/ESG (eletronic


programming/service guide), device mgmt, ...
Middleware, settop box
DRM (digital rights mgmt)
Today’s conditional access system not enough
3
Talk Outline

Service Architecture Overview
Comparison of Design Choices [Cha06-1]
 Path Protection Routing in WDM Mesh Networks
[Cha06-2]
 Efficient and Scalable Algorithms [Cha06-3]

4
Service Architecture of IPTV
Super Hub Offices (SHO)
SHO
Backbone Distribution
Network
VHO
How can
Regional
Network
we provide reliable IPTV services
TV
over the backboneBroadcast
network?
VoD
VHO
Video Hub Office
(VHO)
Regional
Network
Regional
Network
customers
2 SHOs and 40 VHOs across the US
5
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
6
Comparison of Design Choices
Design Space
 Technology: layer 1 optical vs. layer 3 IP/MPLS
 Service layer topology: hub-and-spoke vs. meshed (ring
based)
Access connections: dual-homed vs. ring
Backbone
Backbone
VHO
Dual-homed
Ring
8
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
switching
Optical layer SONET protection
Dst
protection path
IP layer fast-reroute (FRR)
9
Potential IPTV Designs
IP 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
Optical design
10
Alt #1: Integrate With Existing IP Backbone

Support IPTV as multicast application (VoD as unicast)

VHO receives single stream from the nearest SHO
SHO
SHO
Backbone
VHO



VHO
Single network to manage
Backbone links are shared (careful QoS)
Various access connections, fast-failover schemes
11
Alt #2: Dedicated Overlay of Existing IP Backbone

Inter-connect common backbone routers with dedicated
SHO
links
SHO
VHO



Backbone
Backbone links are dedicated for IPTV (no QoS)
Overhead for managing overlay
Various access connections, fast-failover schemes
VHO
12
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
SHO
SHO

Meshed topology
(carry “through” traffic)
VHO
VHO
Long haul links
13
Alt #4: Integrating with Existing Optical Backbone


Multicast capabilities at optical nodes (new technology)
SHOs establish multicast trees, VHO receiving single best
stream
SHO
SHO
L1 network
VHO

Fast-failover is not yet supported in optical multicasting
14
Review: Design Choices
IP or optical
Technology
Hub-and-spoke or highly meshed
Link capacity
Service layer topology
Dedicated or shared
Fast-failover
SONET links, fast-reroute,
or physically diverse paths
Access
Dual-homed or ring
15
Design Instances
Design
Layer
Link-Capacity
Access Type
Fast-Failover
Int-IP-HS
Alt #1
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
Alt #2
Ded-IP-HS
Ded-IP-HS-FRR
Ded-IP-Ring
Ded-IP-Ring-FRR
IP
..
..
..
Dedicated
..
..
..
Dual-homed
..
Ring
..
SONET links
P2P-DWDM Alt #3 Optical
P2P-DWDM-FRR
..
Dedicated
..
None
..
Fast re-route
Opt-Switched Alt #4 Optical
Time-divisioned
Dual-homed
Disjoint paths
Fast re-route
SONET links
Fast re-route
SONET links
16
Cost Analysis: Capital Expense vs Traffic Loads
comparison
demands b Gb/s
Ma+Ub: Cost
multicast
a across
Gb/straffic
+ unicast
20.0
Relative cost
Int-IP-HS-FRR
Opt-Switched
15.0
access
10.0
backbone
Multicast

Multicast
+
Unicast
Multicast
M3+U3
M2+U2
M1+U1
M3+U0
M2+U0
M1+U0
M3+U3
M2+U2
M1+U1
M3+U0
M2+U0
0.0
M1+U0
5.0
Multicast
+
Unicast
Increase in VoD loads has significant impact on the overall cost.
→ Having highly accurate VoD load forecasts is important! 17
Capital Expense Across Designs (Broadcast TV)
Multicast 3Gbps + Unicast 0Gbps
6.0
Relative cost
5.0
4.0
acces s
backbone
3.0
2.0
1.
2.
3.
Opt-Switched
P2P-DWDM-FRR
P2P-DWDM
Int-IP-Ring-FRR
Int-IP-Ring
Int-IP-HS-FRR
Int-IP-HS
Ded-IP-Ring-FRR
Ded-IP-Ring
Ded-IP-HS-FRR
0.0
Ded-IP-HS
1.0
Optical designs are more economical than IP-based ones.
Cost is dominated by access part (except for flat IP designs).
18
For IP designs, FRR is economical then using SONET links.
Access Structure vs Traffic Loads
Multicast 3Gbps + Unicast
0Gbps
multicast
only
Multicast 3Gbps + +
Unicast
3Gbps
multicast
VoD
Ring access
40.0
Relative cost
5.0
4.0
acces s
backbone
3.0
2.0
Relative cost
6.0
Dual-homed access
30.0
access
20.0
backbone
10.0
multicast only

Opt-Switched
P2P-DWDM-FRR
P2P-DWDM
Int-IP-Ring-FRR
Int-IP-Ring
Int-IP-HS-FRR
Int-IP-HS
Ded-IP-Ring-FRR
Ded-IP-Ring
Ded-IP-HS-FRR
Ded-IP-HS
multicast + VoD
Ring access is more economical when only multicast traffic is
considered. Dual-homed is better for VoD (no through traffic).
Ring

0.0
Opt-Switched
P2P-DWDM-FRR
P2P-DWDM
Int-IP-Ring-FRR
Int-IP-Ring
Int-IP-HS-FRR
Int-IP-HS
Ded-IP-Ring-FRR
Ded-IP-Ring
Ded-IP-HS-FRR
0.0
Ded-IP-HS
1.0
Dual-homed
Flat IP design becomes expensive when VoD considered.
19
Summary
 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
20
Path Protection Routing
in
WDM Mesh Networks
Motivation
Optical design known most economical [cha06-01]
 Fast fail-over not yet available in optical multicast

Provisioning approach in optical backbone [SRLG]
- Design multicast trees (from SHOs to VHOs) in a
failure-resilient and cost-effective manner
22
What is SRLG (Shared Risk Link Group)?

Layered architecture
Link failure in one layer → multiple failures in the upper layer
Two disjoint links may belong to a common SRLG
23
Examples of SRLGs
two sources
path
risks
conduit
bridge, tunnel
multiple destinations
24
Requirements
of IPTV
IPTVService
Backbone
Design
Goals

Fault Tolerance
 Customers expect “always-on” service
 Resiliency against SRLG failures
Use redundant SRLG diverse paths from SHOs to VHOs

Low Cost
 To be competitive in the market
 Each link associated with port / transport cost
Find minimum cost multicast trees
25
Protection Routing
Routing Problem
Path Path
Protection
Problem
SHO
SHO
Backbone
VHO
VHO
VHO
VHO
VHO
How to create two multicast trees such that
(1) provisioning cost is minimized and
(2) VHOs have physically disjoint paths to SHOs?
26
Link-Diverse vs SRLG-Diverse
Multicast path by s1
unused
Multicast path by s2
risk1
d1
s1
risk1
s2
d2
d1
s1
risk2
d3
(a) Link-diverse routing, cost=8
s2
d2
risk2
d3
(b) SRLG-diverse routing, cost=9
27
An SRLG-Diverse Solution: Active Path First
1. Construct a minimum spanning tree from one source
2. Remove all SRLG links of the first tree
3. Build the second minimum spanning tree with remaining links
risk1
d1
s2
s1
d2
d1
s1
s2
d2
risk2
d3
d3
First tree from s1
Second tree from s2 (reduced graph)
(a) Active Path First routing, cost=10
28
Trap Situation of APF
risk1
d1
s1
s2
d2
d1
s1
s2
d2
risk2
d3
d3
First tree from s2
Fail to find second tree from s1
(b) Active Path First routing, trap situation
29
Our Provisioning Approach

Include SRLG-diverse constraints and solve the
problem thru Integer Programming (IP)

Compare against
 APF (Active Path First) heuristic
 Less resilient source-diverse design
 Less resilient link-diverse design
30
Integer Programming Formulation
Minimize total cost
Flow
conservation
SRLG
diversity
31
Applying Our IP Formulation

Dataset
2 SHO and 40 VHO locations in the US

IP formulation amenable to realistic topologies!
32
Cost Comparison Across Designs
Most reliable
Reduced reliability
Most Reliable Reduced reliability
cost
ILP design more economical than heuristic.
Cost for increased reliability affordable.
33
Summary

First work on supporting IPTV on optical mesh
network with SRLG constraints

Compact Integer Programming formulation
 Minimum design cost
 SRLG-diversity shown affordable
34
Efficient and Scalable Algorithms
for Large Network Topologies
Motivation

Improve path quality
 Set maximum latency
 Limit # of intermediate nodes and links

Solving an ILP exact algorithm not scalable
Net3
36
New Heuristic Approach

Divide-and-Conquer technique for large network
topologies:
 Partition the problem into smaller ones
 Solve each small problem
 Integrate the solutions “well”
37
Proposed Heuristics

Greedy Local (GL)



Improved Greedy Local (IGL)



Do GL and find the minimum cost graph
Fix the shorter of the two paths and solve the rest
Adaptive Search



Divide into subgraphs with two sources and a destination
Solve for each graph, and consolidate solutions
Use any routing algorithm to find initial tree
Find SRLG-diverse paths; for those w/o such, run baseline ILP.
Modified Active Path First


Build one MST first; then for each destination, check if a SRLGdiverse path exists.
If yes, then fix the path; otherwise, run baseline ILP.
38
Greedy Local (GL)


Step1: For each VHO, find redundant SRLG diverse paths by ILP
Step2: Consolidate solutions
SHO
SHO
SRLG
SRLG
Consolidate!
SRLG diverse
diverse
diverse
VHO
VHO
VHO
39
Improved Greedy Local (IGL)



Step1: Run GL
Step2: For each VHO, fix the shorter path
Step3: Find missing paths all together using ILP
SHO
SHO
only
FindLeave
Solution
missing
from
paths
GL
shorter paths
VHO
VHO
VHO
40
Adaptive Search (AS)


Step1: Use any initial routing scheme to find paths
Step2: For each VHO, make sure paths are SRLG-diverse
SHO
SHO
Initial routing paths
SRLG-diverse?
VHO
Yes!
Then, fix as solution.
VHO
VHO
SRLG-diverse?
No!
Then, replace with SRLG diverse paths.
41
Modified Active Path First (MAPF)



Step1: Find minimum spanning tree from one source
Step2: For each VHO, make sure SRLG counterpart part path exists
Step3: Find the missing paths all together using ILP
SHO
SHO
Not
possible!
Find missing
Minimum paths w/ ILP
SRLG
spanning
diverse
treeSRLG
VHO
Does SRLG-diverse
diverse
counterpart path exist? VHO
Yes!
VHO
Then, fix as solution.
Does SRLG-diverse counterpart path exist?
No!
Then, replace with SRLG diverse paths.
42
Capital Expense Comparison
Net5 (800sec)
Net6 (2sec)
43
CAPEX Scalability Analysis
Net5
44
Computation Time Analysis
Net5
45
Summary

Additional quality improvements of SRLG-diverse
paths
 latency limits
 # of intermediate nodes and links
 per-path upper bound of SRLGs

Efficient and scalable solutions for realistic network
topologies
46
Implications for Other Networks

Cross-layer optimization
 Optical + IP layer info combined

Topological constraints
 Mesh vs star
 WAN vs MAN

Cost constraints
 OXC port vs router port
47
IPTV Service Monitoring [Kerpez]

Elements of IPTV Service Assurance
 Subscriber management
Billing, subscriptions, AAA, DRM
 Video headend
Converged services, VoD, Broadcast
 Transport network
IP/MPLS, Ethernet, DSLAM/OLT, Gateways
48
References
[Cha06-1] Cha et al., “Case study: resilient backbone design for IPTV services,” IPTV Workshop
(WWW 2006), Edinburgh, May, 2006.
[Cha06-2] Cha et al., “Path protection routing with SRLG constraints to support IPTV in WDM
mesh networks,” 9th IEEE Global Internet Symposium, Barcelona, April, 2006.
[Cha06-3] Cha et al., “Efficient and scalable provisioning solutions for always-on multicast
streaming services,” (in submission).
[SRLG] Sebos et al., “Auto-discovery of shared risk link groups,” IEEE OFC, March 2001.
[APF] Xu et al., “On the complexity of and algorithms for finding the shortest path with a
disjoint counterpart,” IEEE/ACM ToN, 14(1):147-158, 2006.
[Kerpez] K. Kerpez et al., “IPTV Service Assurance,” IEEE Communications, September, 206
49