international conference on communications (icc 2004)

International Conference on Communications (ICC 2004)

Broadband Communications and

Distributed Systems GroupUniversitat de Girona

Enhancing fault management performance of two-step QoS routing algorithms in GMPLS

networks

Eusebi Calle, Jose L Marzo, Anna Urra. L. Fabrega

[email protected]

Contents


Distributed Systems Group

Universitat de Girona

Background (Fault Management)

The failure probability and impact

Two-step and one-step routing methods

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

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

1.2 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) ...

Contents

1. Fault Management





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

Contents

1. Fault Management





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)

Contents

1. Fault Management





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 ManagementContents

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


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


Very Low Packet Loss

Disadvantages

Fast Failure Recovery Time

High Resource

Consumption

Contents

1. Fault Management





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

Contents

1. Fault Management





Recovery phaseFault 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)

IETFCCAMPCommon Control and Measurement Plane

Intenet Drafts

Rabbat, Sharma...

2. Reducing failure probability and impactContents

1. Fault Management





Geographical Conditions

Failure Probability

Models:

MIL-HDBK-217

Bellcore/Telcordia

Initial Link Failure

Probability

Statistical Failure Values

Network Components

Current Link Failure

Probability LFP

LFP1 LFP2 LFP3 LFPN

N

1i

iLFPFP_LSP

Label Switch Path Failure Probability

Label Switch Path

2.4 Failure Probability

….

MTTR

MTBF

FR


1. Fault Management





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 = LFP

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

2.5 Residual Failure Probability


1. Fault Management





Low Failure ProbabilityHigh Failure Probability2.6 Case Study

Separated Links to be protected

Working path

1 3 7

42 6

5

Local

Working path

Global Backup

1 3 7

42 6

5

Working path

1 3 7

42 6

5

Local

Working path

1 3 7

42 6

5

Working path

1 3 7

42 6

5

Working path

1 3 7

42 6

5

Local Backup

Working path

1 3 7

42 6

5

Local Backup

s

Working path

Global Backup

1 3 7

42 6

5

Segment

Consecutive links to be protected


1. Fault Management





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

Contents

1. Fault Management





2. Reducing failure probability and impact

1 3 7

42

6 8

5

Shortest Working Path

Two-step routing

Low FailureProbability

High FailureProbability

1 3 7

42

6 8

5

Working path

Backup Path

3.1 Two-step versus One-step routing

3. Two-step vs One-step routing algorithms

Trap Topologies (MHA + Global Protection)

Working path

1 3 7

42

5

One-step routing

Backup Path

6 8

Smart Protection

Fast Recovery Time

Low Packet Loss

Low Resource Consumption

Advantages

Low Failure Probability

Contents

1. Fault Management





4.1 Failure Probability Analysis (*)


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

Req

uest

Rej

ectio

n R

atio

Trial Number

0

500

1000

1500

2000

2500

3000

<2 2 3 4 5 6 7

WSP

PWSP_FPT (NPT)

PWSP_FPT (PT)

Failure Probability Distribution

Num

ber

of L

SP

Failure Probability evaluation. Traffic differentiation. Dynamic Traffic

0

1

2

3

4

5

6

Non Protected Traffic

Protected Traffic

No Traffic Differentiation

Time

LS

P

fail

ure

prob

abil

ity

10 - 4

Failure Probability evaluation. Traffic differentiation. Incremental Traffic

Residual Failure Probability evaluation. Request Rejection Ratio

No protection

Incremental / Dynamic exp.

Traffic Differentiation

Modified WSP

Contents

1. Fault Management





Non Protected TrafficProtected Traffic

Net

wor

k R

esid

ual

Fai

lure

Pro

babi

lity

0

0,1

0,5

0,2

0,3

0,4


Protected Traffic

0

0,1

0,5

0,2

0,3

0,4

Net

wo

rk R

esid

ual

Fai

lure

Pro

bab

ilit

y


Protected Traffic

TimeTime

Residual Failure Probability evaluation. Segment Backups and traffic differentiation.

Residual Failure Probability evaluation. Local Backups and traffic differentiation.

4.2 Residual Failure Probability Analysis

Local and segment protection

Dynamic traffic, Traffic Differentiation, Modified WSP

Similar RFP, Local (more resource requirements) but minor failure impact.

Contents

1. Fault Management






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

Contents

1. Fault Management






Distributed Systems GroupUniversitat de Girona

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

[email protected]

Thank you !

international conference on communications (icc 2004)

Documents

fault management2

fault managementcontents1

fault management1

fault managementm

failure probability

onestep routing4

mplsgmpls fault management

experimental results5