Enhanced Protection using Shared Segment Backups in a Multiservice GMPLS-based Networks Anna Urra, Eusebi Calle, Jose L Marzo Institute of Informatics and Applications (IIiA) ISCC 2005

Contents Universitat de Girona Background (Fault Management) The failure probability and impact Enhanced Protection using Shared Segment Backups in a Multiservice GMPLS-based Networks Experimental results 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 FIS : Fault Indication Signal

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. Fault Management 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. Working Paths Backup Paths 1:1M:11:N M:N0: The M:N model

1. Fault Management 1.4 a) Path provisioning classification 1.4 b) Resource allocation classification Path Provisioning Computed on demand Pre-computed Established on demand Pre-established Resource pre-allocated Resource allocated on demand Resource allocation Dedicated (1:1 or 1+1) Shared (1:N, M:N) No resources (1:0)

Egress Node PML Ingress node PSL Working Path Global Backup Path a) Global Backup Path Advantages Path Protection ( 1 PSL, 1 PML ) Disadvantages Slow Failure Recovery Time Packet Loss 1. Fault Management

Egress Node Ingress node Working Path Global Backup Path b) Reverse Backup Path Reverse Backup Path Advantages Path Protection Low Packet Loss Disadvantages Slow Failure Recovery Time Packet reordering High Resource Consumption 1. Fault Management

Egress Node Ingress node Working Path c) Local Backup Path Local Backup Path Advantages Fast Failure Recovery Time Low Packet Loss Disadvantages High Resource Consumption (Path Protection) 1. Fault Management

1.5.d) Segment Backup Path Egress Node Ingress node Working Path Segment Backup Path AdvantagesDisadvantages 1. Fault Management

1.5.e) 1+1 Protection 1. Fault Management Egress Node Ingress node Path Path 1 Advantages Path Protection Very Low Packet Loss Disadvantages Fast Failure Recovery Time High Resource Consumption

2. Reducing failure probability and impact 2.1. Enhanced Protection using Shared Segment Backups in Multiservice GMPLS-based 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…) No Multilevel protection considerations (protection duplications) Objectives Protection as a main routing objective Low complexity Low resource consumption (shared protection) Traffic differentiation Min. Failure Probabilities Reducing Failure Impact Multilevel protection (avoid protection duplications)

Recovery phase Fault detection (T DET ) Hold off time (T HOF ) Notification time (T NOT ) New Backup creation (T BR + T BS ) Backup Activation (T BA ) Switchover (T SW ) Complete recovery (T CR ) 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 2.3 Minimization of the Failure Recovery Time (Failure Impact) 2. Reducing failure probability and impact Failure NotificationTime Node and link delays to transmit the Failure Indication Signal (FIS) Link Delay : Tprop and Ttrans Node Delay : Queueing and processing time Working LSP Backup LSP Tprop (2000 km) = 10 ms

Residual Label Switch Path Failure Probability LFP = 1·10 -4 LFP = 4·10 -4 Working path RFP = (1+4)= 5 Working path Local Backup RFP = 1 Working path Local Backup s RFP = 0 Working path Segment Backup RFP = 0 Working path Global Backup RFP = 0 Working path RFP = 0 2. Reducing failure probability and impact LFP = 0 (WDM protected)

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). Protection assignment for class types based on the network failure probability and failure impact 2.7 GMPLS Protection with traffic differentiation 2. Reducing failure probability and impact

3.1 Selecting the LSP protected segments 3. Enhanced Protection using Shared Segment Backups in a Multiservice GMPLS-based Networks WP link (WDM non protected) Segment BackupWP link (WDM protected) (10 -4 )

3.1 Proposed algorithms 3. Enhanced Protection using Shared Segment Backups in a Multiservice GMPLS-based Networks Segment protection FRRM_F1 : FRRM with FIR and 1 Level of protection. This scheme considers that the FIR computes the backup path when the candidates are selected. FRRM_W1 : FRRM with WSP and 1 Level of protection. This algorithm considers that the WSP computes the backup path. FRRM_F2 : FRRM with FIR and 2 Level protection. This scheme considers that the FIR computes the backup path when the candidates are selected. In this scheme one-level algorithm is not applied. FRRM_W2 : FRRM with WSP and 2 Level protection. In this scheme, one-level algorithm is not applied and the WSP computes the backup path. Global/path protection G_WSP and G_FIR.

4. Experimental results

Restoration Overbuild a) b) c)c) d)d) Time Trial % of non protected WDM links Restoration Overbuild Level of Sharing FRRM_W2FRRM_F2 G_FIRG_WSP FRRM_F1FRRM_W1 FRRM_W1 (AF) FRRM_F1 (AF) FRRM_W1 (EF) FRRM_F1 (EF) FRRM_F1 FRRM_W1 FRRM_F1 FRRM_W1

5. Summary and conclusions 5.1 Summary and conclusions In this paper novel protection schemes for Fast Recovery and Reliable Multiservices (FRRM) label switch paths have been presented in a GMPLS scenario with traffic differentiation. The tradeoffs between the minimization of the recovery time and failure probabilities with suitable resource consumption have been considered. Using shared segment backup paths allows the reliability and failure impacts required for each traffic service to be supported. For each working path only one backup path is computed, simplifying fault management and the routing schemes. Shared backups also optimize resource consumption. Another interesting contribution is that the FRRM algorithms avoid protection duplication by considering those segments already protected at the WDM layer. The results also show that FRRM algorithms perform suitably in different network scenarios with varying amounts of WDM protected segments.

ISCC 2005 Eusebi Calle, Jose L Marzo, Anna Urra Thank you ! Enhanced Protection using Shared Segment Backups in a Multiservice GMPLS-based Networks