Slides Pagano RSVP TE

8/6/2019 Slides Pagano RSVP TE

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RSVP-TE Extensions for

LSP Rerouting in NS2

D. Adami, C. Callegari, S. Giordano, M. PaganoDepartment of Information Engineering - University of Pisa

6-7 December 2007

IST Congress Center, Lisbon, Portugal

Workshop on IP QoS and Traffic Control


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Outline

Introduction

MPLS-based Recovery

RSVP-TE Reservation Styles

NS2 Software Modules

Simulations Results

Conclusions


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Introduction

Multiprotocol Label Switching (MPLS) provides: Traffic Engineering capabilities

Virtual Private Networks support Network Survivability

172.16.0.0/16

InLab

-

...

AddressPrefix

172.16

...

OutI/F

1

...

OutLab

30

...

InI/F

3

...

In

Lab40

...

Address

Prefix172.16

...

Out

I/F1

...

Out

Lab-

...

In

I/F3

...

LSRCLSRC

LSR BLSR B

LSR ALSR A data172.16.1.230

data172.16.1.240

data172.16.1.2

data172.16.1.2172.58.0.0/16

Transit LSRTransit LSR (Label swapping)(Label swapping)

In

Lab

30

...

Address

Prefix

172.16

...

Out

I/F

1

...

Out

Lab

40

...

In

I/F

3

...

Ingress LSRIngress LSR (Label pushing)(Label pushing)

Egress LSREgress LSR (Label popping)(Label popping)


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R8R1

R2

R3

R4

R5

LSR8

R7 R6

IP Routing

R9

ShortestPath

High Convergence Time!

IssuesIssues

Highly reliable services require very low recovery times (tenths of ms)IP routing does not assure QoS recovery


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IngressLER

Working LSP

Backup Path

EgressLERLSR1

LSR2

LSR3

LSR4

LSR5

LSR8

LSR7 LSR6

MPLS Recovery: Path Protection

MPLS-based Recovery aims at reducing the recovery timeswhen a failure occurs and dynamic routing protocols are used!


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MPLS Recovery: Path Restoration

IngressLER

EgressLERLSR1

LSR2

LSR3

LSR4

LSR5LSR8

LSR7 LSR6

Working LSP

Backup Path

MPLSMPLS--basedbased RecoveryRecovery ObjectivesObjectivesOptimal use of network resources

Traffic protection with different granularityMinimization of unprotected traffic degradation


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The Recovery Cycle

IngressLER

EgressLERLSR1

LSR2

LSR3

LSR4

LSR5

LSR8

LSR7 LSR6

PathTear

PathErr

Path

Resv

Path

Traffic

Recovered

Recovery

Operation

Complete

Start of

Recovery

Operation

Start of

Notification

Fault

Detected

Network

Impairment

Fault DetectionFault DetectionTimeTime

FaultFault HoldHold--offoffTimeTime

TrafficTraffic RecoveryRecoveryTimeTime

FaultFault NotificationNotificationTimeTime

RecoveryRecovery

OperationOperationTimeTime


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RSVP-TE Reservation Styles

Wildcard-Filter(WF) style

Wildcard SenderSelection

Shared-Explicit(SE) style

Fixed-Filter(FF) style

Explicit SenderSelection

Shared ReservationDistinct Reservation

A reservation style indicates whether senders in the RSVP session havedistinct or shared resource reservation and whether they are selectedaccording to an explicit list

RSVP defines three different Reservation Styles

the FF style creates a distinct reservation for each sender the SE style allows a receiver to make a single reservation shared by a set of

senders explicitly specified in the reservation message the WF style creates a single reservation that is shared by all senders in the

session


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RSVP-TE Reservation Styles: Application Scenario

(1,50)

(2,100)

(1,100)

(1,100)

(1,50)

(5,100)

(2,100)

(1,100)

(1,50)

A

B C

D E

F

LSP (A_B_C_F)

40 Mbps

Bandwidth70 Mbps

New PathA_D_B_C_F

Without SE Reservation Style, it isnecessary to tear down the old LSP and

to set-up a new LSP

(Metric, Bandwidth)


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Motivations and targets

Since planning MPLS-based recovery strategies involves trade-offsbased on several factors

End-user applications requirements

Network efficiency Complexity Revenues

our goal was to develop a powerful and flexible simulation tool to help

network designers and administrators in their work

An MPLS Network Simulator (MNS) was available for the NetworkSimulator 2 (NS2)

developed at Chungnam National University, Korea based on the Constrained Routing Label Distribution Protocol (CR-LDP)

buta full open-source MPLS networks simulation tool had not beenrealized yet!!


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NS2 Software Modules

MNS - MPLS Network SimulatorOld Modules

New Modules

RSVP-TE\ns with Reservation Styles

OSPF-TE\ns

MPLS Recovery Strategies

QoS Routing


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New MPLS Node Architecture in NS2

OSPF-TEmodule

OSPF-TEmodule

RSVP-TEmodule

RSVP-TEmodule


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LSP Recovery in NS2

LSP Protectionprotection-ff

protection-se

LSP Rerouting with Path Precomputation fastrerouting-ff

fastrerouting-se


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Simulation Scenario

GANT

Pan-European multi-gigabitdata communications networkspecifically reserved forresearch and education use

The GANT project was acollaboration between 26National Research andEducation Networksrepresenting 30 countries

The network connects a totalof 34 countries


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Simulation Scenario

Simulation Scenario

Available Bandwidth = 1 Mb/s

CBR Sources at 400 Kb/s Link cost = 1

A failure on the link 7_22 of the

primary LSP is forced Fault Hold-off Time = 0

TargetTarget

To highlight the advantages ofusing SE Reservation Styles

CBR TrafficDestination

CBR TrafficSource

PrimaryPrimary

LSPsLSPs


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LSP Rerouting with FF Reservation StyleDestinations

CBR TrafficSources

Reserved

LSP

Back-Up LSPs

PRIMARY

LSPs

IP Shortest Path


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Recovery Time for FF Reservation Style

620

640

660

680

700

720

740

760

780

1 2 3 4 5 6 7 8 9 10

Simulation

ms

LSP 1 LSP 2

Link status is checked by a polling mechanism, simulated as a randomvariable uniformely distributed within [0, 100 ms]


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LSP Rerouting with SE Reservation Style

Destinations

CBR TrafficSources

Reserved

LSP

Back-Up LSP

PRIMARY

LSP


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0

20

40

60

80

100

120

140

160

180

1 2 3 4 5 6 7 8 9 10

Simulation

ms

Recovery Time for SE Reservation Style

Avg. Recovery Time: 126 ms vs. 736 ms


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Conclusions

Design and development of a new NS2 software module which enhancesRSVP-TE\ns with the reservation styles supported by RSVP-TE

The availability of reservation styles allows MPLS network designers toplan complex scenarios with heterogeneous recovery strategies

The new NS2 module may help a network designer to choose the most

suitable MPLS-based recovery strategy

Reservation styles are also essential to set-up Point-to-Multipoint andMultipoint-to-Multipoint LSPs

The software is available on the TlcNetGroup software repository at thesite:

http://netgroup-serv.iet.unipi.it

Documents

Slides Pagano RSVP TE