Applicability of OSPF TopologyTransparent Zone
Huaimo Chen ([email protected])
Renwei Li ([email protected])
Gregory Cauchie ([email protected])
Ning So ([email protected])
Lei Liu ([email protected])
Contents
• Introduction
• Applicability of TTZ
–
–
–
–
One Area Network
Multiple Area Network
Use of TTZ in IPRAN
Use of TTZ for POP
• Deployment Considerations
Page 2
Introduction
• What will happen if number of routers in
AS is bigger and bigger?
– Operation is harder when split into areas further (Network
Architecture changes)
– It is difficult for a MPLS TE LSP crossing areas to be established
– Route convergence is slower
• Show how TTZ resolve these issues
Page 3
What is TTZ?
•
R6
T3
T3
T2
R1
R2
T1
T1
R7
T6
T5
T7
R8
T9
R9
T8
T4
T4
R3
TTZ
R4
R5
R10
T10
T10
R11
•
A group of routers connected by links with attribute TTZ ID.
•
Routers outside of TTZ are NOT aware of TTZ, just see the edge routers of
TTZ, which are connected.
•
Links, routers inside TTZ are NOT advertised to routers outside of TTZ.
Contents
• Introduction
• Applicability of TTZ
–
–
–
–
One Area Network
Multiple Area Network
Use of TTZ in IPRAN
Use of TTZ for POP
• Deployment Considerations
Page 5
One Area Network
Area 4
R
T
R
T
T
1
2
3
5
R
R
3
T
6T
T
R
4
4
R
6
1
9
T
1
2
R
R
8
2
R
3
9
5
3
R
6
T
T
5
R
8
T
7
7
T
2
R
R
T
T
1
5
R
T
Area 1
6T
T
9
7
R
7
8
T
T
R
4
Area
0
8
R
4
1
1
0
0
9
T
T
Area 3
R
R1
0
Area 0
10
Issues on Splitting Network into Areas:
1. Significant changes on Network Architecture and configurations
2. Complex for E2E TE LSP crossing areas to be set up
3. Policy Configurations and Slow Convergence
Page 6
R
Area 2
Use of TTZ in One Area Network
T3
T3
T2
T
T1
T1
3
T6
T
T5
3
T7
T
T9
1
T
1
T4
T4
0
T8
T
0
TTZ 1
3
T10
T10
T
T
3
1
0
T
1
T
0
3
T
Area 0
3
T
T
1. No Significant Changes
on Network Architecture
(No need to split area )
1
1
2. TE LSP can be set up easily
0
0
3. No Policy Configurations and Fast Convergence
Page 7
E2E TE LSP can be set up easily
•
T3
T3
R5
T2
R1
T1
T1
R6
T6
T5
T7
R7
T9
T4
T4
R8
T8
Destination
R2
TTZ
R3
Source
R4
Find path from
R3 to R6 in a
normal way
T10
T10
R9
R10
Find path from
T4 to T10 in a
normal way
Path for LSP is computed easily in a normal way
LSP can be set up along the path computed
Page 8
Contents
• Introduction
• Applicability of TTZ
–
–
–
–
One Area Network
Multiple Area Network
Use of TTZ in IPRAN
Use of TTZ for POP
• Deployment Considerations
Page 9
Multi-Area Network
Area4
Area 7
Area 5
Area4
Area1
Area1
T
7
Area0
Area0
Area 3
Area 3
Area2
Area 2
Area 6
What happens when splitting a multi-area network into more areas?
1. Significant Changes on Network Architecture (Re-arranging & splitting areas)
2. More Configurations for Tunnel Setup
3. More Policy Configurations
Page 10
Use of TTZ in Multi-Area Network
Area 4
Area 1
T3
T2
T1
R1
T6
T5
T7
R7
T9
R2
T8
T4
R3
Area 0
R9
T10
R4
Area 3
R10
Area 2
1. No big changes on Network Architecture (No need to split areas)
2. No Extra Configurations for Tunnel Setup
3. No More Policy Configurations
Page 11
Contents
• Introduction
• Applicability of TTZ
–
–
–
–
One Area Network
Multiple Area Network
Use of TTZ in IPRAN
Use of TTZ for POP
• Deployment Considerations
Page 12
Use of TTZ in IPRAN
Area 0
Area 1
R4
T3
T2
T1
R1
BSC/RNC
T6
T5
T7
T9
R2
T4
R3
T10
Area 0
R4
R1
T3
T2
BSC/RNC
T1
T6
T5
TTZ
T7
T9
R2
R3
T10
T4
Convert network into backbone area 0 via TTZ
1. Easy E2E TE LSP Setup over optimal path
2. TE LSP within one area can be easily protected using FRR
3. Operation is easier
Page 13
Contents
• Introduction
• Applicability of TTZ
–
–
–
–
One Area Network
Multiple Area Network
Use of TTZ in IPRAN
Use of TTZ for POP
• Deployment Considerations
Page 14
Use of TTZ for POP
POP 3
T3
T2
POP 1
T
T1
3
T6
T
TTZ 3
T5
3
T7
TTZ 1
T
T9
1
T
POP
20
0
T8
1
T4
POP 4
T
3
T10
T
TTZ 2
3
T
TTZ 4
1
T
0
1
0
1. Increase the network scalability
2. Improve the network availability
Page 15
Contents
• Introduction
• Applicability of TTZ
–
–
–
–
One Area Network
Multiple Area Network
Use of TTZ in IPRAN
Use of TTZ for POP
• Deployment Considerations
Page 16
Deployment Considerations
• Number of edge routers of a TTZ should
be small
• A TTZ is within an OSPF area
Next Step
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