Broadband Communications and

Distributed Systems GroupUniversitat de Girona

Enhanced Protection using Shared Segment Backups in a Multiservice

GMPLS-based Networks

Anna Urra, Eusebi Calle, Jose L MarzoInstitute of Informatics and Applications (IIiA)

eusebi@eia.udg.es

ISCC 2005

Contents

Broadband Communications and

Distributed Systems Group

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.

1 3 5 7 9

42 6 8

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 3 5 7 9

42 6 8

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 PathsBackup Paths

1:1 M:1 1:N

M:N 0:1 1+1

1.3 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

1 3 5 7 9

42 6 8

1.5.a) Global Backup Path

AdvantagesPath Protection

( 1 PSL, 1 PML )

Disadvantages

Slow Failure Recovery Time

Packet Loss

1. Fault Management

Egress Node

Ingress node

Working Path

Global Backup Path

1 3 5 7 9

42 6 8

1.5.b) Reverse Backup Path

Reverse Backup Path

AdvantagesPath Protection

Low Packet Loss

Disadvantages

Slow Failure Recovery Time

Packet reordering

High Resource Consumption

1. Fault Management

Egress Node

Ingress node

Working Path

1 3 5 7 9

42 6 8

1.5.c) Local Backup Path

Local Backup Path

AdvantagesFast 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

1 3 5 7 9

42 6 8

Segment Backup Path

Advantages

Disadvantages

1. Fault Management

1.5.e) 1+1 Protection

1. Fault Management

Egress Node

Ingress node

Path 2

1 3 5 7 9

42 6 8

Path 1

AdvantagesPath 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 (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

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 timeWorking LSP

Backup LSP

1 3 5 7 9

42 6 8

Tprop (2000 km) = 10 ms

Residual Label Switch Path Failure Probability

LFP = 1·10-4 LFP = 4·10-4

Working path

1 3 7

42 6

5

RFP = (1+4)= 5

Working path

1 3 7

42 6

5

Local Backup

RFP = 1

Working path

1 3 7

42 6

5

Local Backups

RFP = 0

Working path

Segment Backup

1 3 7

42 6

5

RFP = 0

Working path

1 3 7

42 6

5

Global Backup

RFP = 0

Working path

1+1

1 3 7

42 6

5

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

AF EFMRFP 5 4Tprop (ms) 10 (2000 Km) 5 (1000 Km)

AF EF1-2-3-42-3-4-52-3-4 2-3-43-4 3-4

3-4-5 3-4-53-4-5-64-5-6-7

Including WDM protected links

Not Including WDM protected Links

Candidates

1 2 3 4 5 6 7

WP link (WDM non protected)

Segment BackupWP link (WDM protected)

Links 1-2 2-3 3-4 4-5 5-6 6-7LFP 1 0 4 1 1 1

Lenght (km) 1000 500 1000 500 1000 500

(10-4)

(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

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0

0.02

0.04

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 10a) b)

G_WSP

G_FIR

Time

Restoration Overbuild

Request Rejection Ratio

Trial

FRRM_W2 FRRM_F2FRRM_W1 FRRM_F1G_WSP G_FIR

FRRM_W2 FRRM_F2

FRRM_W1 FRRM_F1

4. Experimental results

0

0.1

0.2

0.3

0.4

0.5

10 27 47 60 80

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

10 27 47 60 80

0

0.1

0.2

0.3

0.4

0.5

0

0.2

0.4

0.6

0.8

1

1 2 3 4 5 6 7 8 9 10

Resto

rati

on

Overb

uild

a) b)

c) d)

TimeTrial

% of non protected WDM links% of non protected WDM links

Resto

rati

on

Overb

uild

Level of

Sh

ari

ng

Level of

Sh

ari

ng

FRRM_W2 FRRM_F2G_FIR G_WSP

FRRM_F1 FRRM_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 faultmanagement 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.

Broadband Communications and

Distributed Systems GroupUniversitat de Girona

ISCC 2005

Eusebi Calle, Jose L Marzo, Anna Urra

eusebi@eia.udg.es

Thank you !

Enhanced Protection using Shared Segment Backups in a Multiservice

GMPLS-based Networks