1. Eusebi Calle, Jose L Marzo, Anna Urra. L. Fabrega
International Conference on Communications (ICC 2004)
Enhancing fault management performance of two-step QoS routing algorithms in GMPLS networks
Eusebi Calle, Jose L Marzo, Anna Urra. L. Fabrega

2. Contents Background (Fault Management)
Universitat de Girona
Contents
Background (Fault Management)
The failure probability and impact
Two-step and one-step routing methods
Experimental results
Summary and conclusions

3. 1. Fault Management 1.1 MPLS/GMPLS fault management. Contents
2. Reducing failure probability/ impact
3. Two-step versus One-step routing
4. Experimental results
5. Summary and Conclusions
1. Fault Management
1.1 MPLS/GMPLS fault management.
Working LSP
Backup LSP
PML Node
PSL Node
Protection Switch LSR (PSL) : switches protected traffic from the working path to the corresponding backup path.
Protection Merge LSR (PML) : merges their traffic into a single outgoing LSP, or, if it is itself the destination, passes the traffic on to the higher layer protocols. 1 3 5 7 9 4 2 6 8
FIS : Fault Indication Signal

4. 1. Fault Management 1.2 Classes of impairments Contents
2. Reducing failure probability/ impact
3. Two-step versus One-step routing
4. Experimental results
5. Summary and Conclusions
1. Fault Management
1.2 Classes of impairments
IETF RFC3469
Path Failure (PF) ...
Path Degraded (PD)...
Link Failure (LF) is an indication from a lower layer that the link over which the path is carried has failed. If the lower layer supports detection and reporting of this fault, i.e. any fault that indicates link failure for example SONET Loss of Signal (LoS), this may be used by the MPLS recovery mechanism.
Link Degraded (LD) ...
SINGLE LINK FAILURES
Working LSP
Backup LSP 1 3 5 7 9 4 2 6 8

5. 1. Fault Management 1.3 The M:N model Contents 1. Fault Management
2. Reducing failure probability/ impact
3. Two-step versus One-step routing
4. Experimental results
5. Summary and Conclusions
1. Fault Management
1.3 The M:N model
M is the number of backup LSPs used to protect N working LSPs
1:1: 1 working LSP is protected/restored by one backup LSP.
M:1: 1 working LSP is protected/restored by M backup LSPs.
1:N: 1 backup LSP is used to protect/restore N working LSPs (shared backups).
M:N : N working LSPs are restored by M backup LSPs
1:0 : No protection (for instance, Best effort traffic)
1+1: Traffic is sent concurrently on both the working LSP and the backup LSP.
1:1
M:1
1:N
M:N
0:1
1+1
Backup Paths
Working Paths

6. 1. Fault Management 1.4 a) Path provisioning classification
Contents
1. Fault Management
2. Reducing failure probability/ impact
3. Two-step versus One-step routing
4. Experimental results
5. Summary and Conclusions
1. Fault Management
1.4 a) Path provisioning classification
Path Provisioning
Computed on demand
Pre-computed
Established on demand
Pre-established
Resource pre-allocated
Resource allocated on demand
1.4 b) Resource allocation classification
Resource allocation
Dedicated (1:1 or 1+1)
Shared (1:N, M:N)
No resources (1:0)

7. 1. Fault Management 1.5.a) Global Backup Path Contents
2. Reducing failure probability/ impact
3. Two-step versus One-step routing
4. Experimental results
5. Summary and Conclusions
1. Fault Management
1.5.a) Global Backup Path
Global Backup Path 2 4 6 8 1 3 5 7 9
Ingress
node
PSL
Egress
Node
PML
Working Path
Advantages
Path Protection
( 1 PSL, 1 PML )
Disadvantages
Slow Failure Recovery Time
Packet Loss

8. 1. Fault Management 1.5.b) Reverse Backup Path Contents
2. Reducing failure probability/ impact
3. Two-step versus One-step routing
4. Experimental results
5. Summary and Conclusions
1. Fault Management
1.5.b) Reverse Backup Path
Global Backup Path 2 4 6 8 1 3 5 7 9
Ingress
node
Egress
Node
Reverse Backup Path
Working Path
Advantages
Path Protection
Low Packet Loss
Disadvantages
Slow Failure Recovery Time
Packet reordering
High Resource Consumption

9. 1. Fault Management 1.5.c) Local Backup Path Contents
2. Reducing failure probability/ impact
3. Two-step versus One-step routing
4. Experimental results
5. Summary and Conclusions
1. Fault Management
1.5.c) Local Backup Path
Local Backup Path 2 4 6 8 1 3 5 7 9
Ingress
node
Egress
Node
Working Path
Advantages
Fast Failure Recovery Time
Low Packet Loss
Disadvantages
High Resource
Consumption
(Path Protection)

10. 1. Fault Management 1.5.d) Segment Backup Path Contents
2. Reducing failure probability/ impact
3. Two-step versus One-step routing
4. Experimental results
5. Summary and Conclusions
1. Fault Management
1.5.d) Segment Backup Path
Egress
Node
Ingress
node
Working Path 1 3 5 7 9 4 2 6 8
Segment Backup Path
Advantages
Disadvantages

11. 1. Fault Management 1.5.e) 1+1 Protection Contents 1. Fault Management
2. Reducing failure probability/ impact
3. Two-step versus One-step routing
4. Experimental results
5. Summary and Conclusions
1. Fault Management
1.5.e) 1+1 Protection
Egress
Node
Ingress
node
Path 2 1 3 5 7 9 4 2 6 8
Path 1
Advantages
Path Protection
Very Low Packet Loss
Disadvantages
Fast Failure Recovery Time
High Resource
Consumption

12. 2. Reducing failure probability and impact
Contents
1. Fault Management
2. Reducing failure probability/ impact
3. Two-step versus One-step routing
4. Experimental results
5. Summary and Conclusions
2. Reducing failure probability and impact
2.1. Enhanced fault recovery methods for protected traffic services in GMPLS networks
Drawbacks and lacks
No protection considerations -> Secondary routing objective (No specific backup routing information)
High complexity (in terms of computation time)
High resource consumption (1+1)
No traffic differentiation
No physical network considerations (availability and reliability)
Failure impact (fault recovery time, packet loss…)
Objectives
Protection as a main routing objective
Low complexity
Low resource consumption
Traffic differentiation
Failure Probabilities
Reducing Failure Impact

13. 2. Reducing failure probability and impact
Contents
1. Fault Management
2. Reducing failure probability/ impact
3. Two-step versus One-step routing
4. Experimental results
5. Summary and Conclusions
2. Reducing failure probability and impact
2.3 Minimization of the failure recovery time (Failure Impact)
Recovery phase
Fault detection
(TDET)
Hold off time
(THOF)
Notification time (TNOT)
New Backup creation
(TBR + TBS)
Backup Activation (TBA)
Switchover
(TSW)
Complete recovery (TCR)
Features
Depends on the technology
Depends on the lower layers
Depends on the Failure Notification Distance and notification method
Depends on the routing and signaling method applied
Depends on the backup distance and signaling cross-connection process
Depends on the node technology
Depends on the backup distance
Time Reduction
Cannot be reduced (except in the case of monitoring techniques)
Setup (0-50 ms)
Minimizing the Failure Notification Distance and optimizing the process
Pre-establishing the backup
Minimizing the backup distance and optimizing the process
Cannot be reduced
Minimizing the backup distance
IETF
CCAMP
Common Control and Measurement Plane
Intenet Drafts
Rabbat, Sharma...

14. 2. Reducing failure probability and impact
Contents
1. Fault Management
2. Reducing failure probability/ impact
3. Two-step versus One-step routing
4. Experimental results
5. Summary and Conclusions
2. Reducing failure probability and impact
2.4 Failure Probability
Label Switch Path Failure Probability
Geographical Conditions
Network Components
Initial Link Failure Probability
Current Link Failure Probability LFP
LFP1 LFP2 LFP3
LFPN
Failure Probability Models:
MIL-HDBK-217
Bellcore/Telcordia
Statistical Failure Values
MTTR
MTBF FR
Label Switch Path …. å = N 1 i
LFP FP _
LSP

15. 2. Reducing failure probability and impact
Contents
1. Fault Management
2. Reducing failure probability/ impact
3. Two-step versus One-step routing
4. Experimental results
5. Summary and Conclusions
2. Reducing failure probability and impact
2.5 Residual Failure Probability
Residual Label Switch Path Failure Probability
Working path 1 3 7 4 2 6 5
RFP = (1+4)= 5 = LFP
Working path 1 3 7 4 2 6 5
Local Backup
RFP = 1
Working path 1 3 7 4 2 6 5
Local Backups
RFP = 0
Segment Backup
Global Backup
1+1
LFP = 1·10-4
LFP = 4·10-4

16. 2. Reducing failure probability and impact
Contents
1. Fault Management
2. Reducing failure probability/ impact
3. Two-step versus One-step routing
4. Experimental results
5. Summary and Conclusions
2. Reducing failure probability and impact
2.6 Case Study
High Failure Probability
Low Failure Probability
Separated Links to be protected
Working path 1 3 7 4 2 6 5
Local
Global Backup
Working path 1 3 7 4 2 6 5
Local Backup
Local Backups
Global Backup
Segment
Consecutive links to be protected

17. 2. Reducing failure probability and impact
Contents
1. Fault Management
2. Reducing failure probability/ impact
3. Two-step versus One-step routing
4. Experimental results
5. Summary and Conclusions
2. Reducing failure probability and impact
2.7 GMPLS Protection with traffic differentiation
Protection assignment for class types based on the network failure probability and failure impact
Protected Traffic services
High-resilience requirement traffic services: Traffic that is very sensible to network faults (like EF diffserv traffic). Residual Failure probability and Failure Impact values should be set up at zero. 1+1 or local backup paths can be used in order to accomplish these values.
Medium-resilience requirement traffic services: Traffic that is sensible to network faults (like AF1 or AF2 diffserv traffic). However, resource consumption should be taken into account to route the working and backup paths. Residual failure probabilities and failure impact values should be bounded in order to achieve the desirable QoS with appropriate resource consumption. Segment and global backups can be used to protect these services.
Non-Protected Traffic services
None-resilience requirement traffic services. No protection requirements are needed (BE traffic).

18. 3. Two-step vs One-step routing algorithms
Contents
1. Fault Management
2. Reducing failure probability/ impact
3. Two-step versus One-step routing
4. Experimental results
5. Summary and Conclusions
3. Two-step vs One-step routing algorithms
3.1 Two-step versus One-step routing
Working path 1 3 7 4 2 5
One-step routing
Backup Path 6 8
Trap Topologies (MHA + Global Protection) 1 3 7 4 2 6 8 5
Shortest Working Path
Two-step routing
Low Failure
Probability
High Failure 1 3 7 4 2 6 8 5
Working path
Smart Protection
Fast Recovery Time
Low Packet Loss
Low Resource Consumption
Advantages
Low Failure Probability
Backup Path

19. Failure Probability Distribution
Contents
1. Fault Management
2. Reducing failure probability/ impact
3. Two-step versus One-step routing
4. Experimental results
5. Summary and Conclusions
4. Experimental results
4.1 Failure Probability Analysis (*)
Failure Probability evaluation. Traffic differentiation. Dynamic Traffic
Failure Probability evaluation. Traffic differentiation. Incremental Traffic 1 2 3 4 5 6
Non Protected Traffic
Protected Traffic
No Traffic Differentiation
Time
LSP
failure probability 10
- 4
Failure Probability Distribution
Number of LSP
Residual Failure Probability evaluation. Request Rejection Ratio
0.06
0.08
0.1
0.12
0.14
0.16
0.18
0.2 1 2 3 4 5 6 7 8 9 10
No traffic differentiation
Protected Traffic
Request Rejection Ratio
Trial Number
No protection
Incremental / Dynamic exp.
Traffic Differentiation
Modified WSP

20. 4. Experimental results 4.2 Residual Failure Probability Analysis
Contents
1. Fault Management
2. Reducing failure probability/ impact
3. Two-step versus One-step routing
4. Experimental results
5. Summary and Conclusions
4. Experimental results
4.2 Residual Failure Probability Analysis
Residual Failure Probability evaluation. Segment Backups and traffic differentiation.
Residual Failure Probability evaluation. Local Backups and traffic differentiation.
Time
Time
Local and segment protection
Dynamic traffic, Traffic Differentiation, Modified WSP
Similar RFP, Local (more resource requirements) but minor failure impact.

21. 5. Summary and conclusions
Contents
1. Fault Management
2. Reducing failure probability/ impact
3. Two-step versus One-step routing
4. Experimental results
5. Summary and Conclusions
5. Summary and conclusions
5.1 Summary and conclusions
Failure Impact
Minimum Failure Notification
Minimum resource consumption (Segment + Probabilities)
Minimum Residual Failure Probabilities
Network Availability and Reliability
Failure probability evaluation models
Resource Consumption
Protected-Traffic Services
Enhanced routing algorithms
Two-step routing methods
Quality of protection degree

22. Eusebi Calle, Jose L Marzo, Anna Urra
Thank you !
International Conference on Communications (ICC 2004)
Enhancing fault management performance of two-step QoS routing algorithms in GMPLS networks
Eusebi Calle, Jose L Marzo, Anna Urra