Michele Pagano1

RSVP-TE Extensions forLSP Rerouting in NS2

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

6-7 December 2007IST Congress Center, Lisbon, Portugal

Workshop on IP QoS and Traffic Control

Michele Pagano2

Outline

• Introduction

• MPLS-based Recovery

• RSVP-TE Reservation Styles

• NS2 Software Modules

• Simulations Results

• Conclusions

Michele Pagano3

Introduction

• Multiprotocol Label Switching (MPLS) provides:Traffic Engineering capabilitiesVirtual Private Networks supportNetwork Survivability

172.16.0.0/16

In Lab-

...

Address Prefix

172.16...

OutI/F1...

Out Lab30...

In I/F3...

In Lab40...

Address Prefix

172.16...

OutI/F1...

Out Lab-

...

In I/F3...

LSRCLSRC

LSR BLSR B

LSR ALSR Adata172.16.1.230

data172.16.1.240

data172.16.1.2

data172.16.1.2172.58.0.0/16

Transit LSRTransit LSR (Label swapping)(Label swapping)In

Lab30...

Address Prefix

172.16...

OutI/F1...

Out Lab40...

In I/F3...

Ingress LSR Ingress LSR (Label pushing)(Label pushing)Egress LSREgress LSR (Label popping)(Label popping)

Michele Pagano4

R8R1

R2

R3

R4

R5LSR8

R7 R6

IP Routing

R9

ShortestPath

High Convergence Time!

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

Michele Pagano5

IngressLER

Working LSP

Backup Path

EgressLERLSR1

LSR2

LSR3

LSR4

LSR5LSR8

LSR7 LSR6

MPLS Recovery: Path Protection

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

Michele Pagano6

MPLS Recovery: Path Restoration

IngressLER

EgressLERLSR1

LSR2

LSR3

LSR4

LSR5LSR8

LSR7 LSR6

Working LSP

Backup Path

MPLSMPLS--basedbased RecoveryRecovery ObjectivesObjectivesOptimal use of network resourcesTraffic protection with different granularityMinimization of unprotected traffic degradation

Michele Pagano7

The Recovery Cycle

IngressLER

EgressLERLSR1

LSR2

LSR3

LSR4

LSR5LSR8

LSR7 LSR6

PathTear

PathErr

Path

Resv

PathTraffic

Recovered

RecoveryOperationComplete

Start ofRecoveryOperation

Start ofNotification

FaultDetected

NetworkImpairment

Fault Detection Fault Detection TimeTime

Fault Fault HoldHold--offoffTimeTime

TrafficTraffic RecoveryRecoveryTimeTime

Fault Fault NotificationNotificationTimeTime

RecoveryRecoveryOperationOperation

TimeTime

Michele Pagano8

RSVP-TE Reservation Styles

Wildcard-Filter(WF) style

Wildcard Sender Selection

Shared-Explicit(SE) style

Fixed-Filter(FF) style

Explicit Sender Selection

Shared ReservationDistinct Reservation

• A reservation style indicates whether senders in the RSVP session have distinct or shared resource reservation and whether they are selected according 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

Michele Pagano9

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

FLSP (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)

Michele Pagano10

Motivations and targets

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

End-user applications requirementsNetwork efficiencyComplexityRevenues

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 Network Simulator 2 (NS2)

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

but…a full open-source MPLS networks simulation tool had not been realized yet!!

Michele Pagano11

NS2 Software Modules

MNS - MPLS Network SimulatorOld Modules

New Modules

RSVP-TE\ns with Reservation Styles

OSPF-TE\ns

MPLS Recovery Strategies

QoS Routing

Michele Pagano12

New MPLS Node Architecture in NS2

OSPF-TE module

OSPF-TE module

RSVP-TE module

RSVP-TE module

Michele Pagano13

LSP Recovery in NS2

• LSP Protection<Ingress-LSR> protection-ff <Source> <Egress> <Dest> <OldSID> <SessionID> <FlowID> <TunnelID> <Rate> <Buffer> <Er>

<Ingress-LSR> protection-se <Source> <Egress> <Dest> <OldSID> <SessionID> <FlowID> <TunnelID> <Rate> <Buffer> <Er>

• LSP Rerouting with Path Precomputation<Ingress-LSR> fastrerouting-ff <Source> <Egress> <Dest> <OldSID> <FlowID> <TunnelID> <Rate> <Buffer> <Er>

<Ingress-LSR> fastrerouting-se <Source> <Egress> <Dest> <OldSID> <FlowID> <TunnelID> <Rate> <Buffer> <Er>

Michele Pagano14

Simulation Scenario

GÉANT

• Pan-European multi-gigabitdata communications network specifically reserved forresearch and education use

• The GÉANT project was a collaboration between 26 National Research and Education Networksrepresenting 30 countries

• The network connects a total of 34 countries

Michele Pagano15

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 of using SE Reservation Styles

CBR TrafficDestination

CBR TrafficSource

PrimaryPrimaryLSPsLSPs

Michele Pagano16

LSP Rerouting with FF Reservation StyleDestinations

CBR TrafficSources

ReservedLSP

Back-Up LSPs

PRIMARY LSPs

IP Shortest Path

Michele Pagano17

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]

Michele Pagano18

LSP Rerouting with SE Reservation StyleDestinations

CBR TrafficSources

ReservedLSP

Back-Up LSP

PRIMARY LSP

Michele Pagano19

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

Michele Pagano20

Conclusions

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

• The availability of reservation styles allows MPLS network designers to plan 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 and Multipoint-to-Multipoint LSPs

• The software is available on the TlcNetGroup software repository at the site:

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