[PPT] - RSVP-TE Extensions for LSP Rerouting in NS2 D. Adami, C. Callegari, PowerPoint Presentation

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RSVP-TE Extensions for LSP Rerouting in NS2

D. Adami, C. Callegari, S. Giordano, M. Pagano

Department 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

In Lab

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Address Prefix

172.16

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Out I/F

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In I/F

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In Lab

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Address Prefix

172.16

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Out I/F

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LSRC LSRC LSR B LSR B LSR A LSR A

data 172.16.1.2

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data 172.16.1.2

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data 172.16.1.2 data 172.16.1.2

172.58.0.0/16 Transit LSR Transit LSR (Label swapping) (Label swapping)

In Lab

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Address Prefix

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Out I/F

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

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R8 R1 R2 R3 R4 R5 LSR8 R7 R6

IP Routing

R9

Shortest Path

High Convergence Time!

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

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Ingress LER

Working LSP Backup Path

Egress LER LSR1 LSR2 LSR3 LSR4 LSR5 LSR8 LSR7 LSR6

MPLS Recovery: Path Protection

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

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MPLS Recovery: Path Restoration

Ingress LER Egress LER LSR1 LSR2 LSR3 LSR4 LSR5 LSR8 LSR7 LSR6

Working LSP Backup Path

MPLS MPLS-

based

based Recovery Recovery Objectives Objectives

Optimal use of network resources Traffic protection with different granularity Minimization of unprotected traffic degradation

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The Recovery Cycle

Ingress LER Egress LER LSR1 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 Detection Fault Detection Time Time Fault Fault Hold Hold-

off
ff

Time Time Traffic Traffic Recovery Recovery Time Time Fault Fault Notification Notification Time Time Recovery Recovery Operation Operation Time Time

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RSVP-TE Reservation Styles

Wildcard-Filter (WF) style Wildcard Sender Selection Shared-Explicit (SE) style Fixed-Filter (FF) style Explicit Sender Selection Shared Reservation Distinct 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

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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 Bandwidth 70 Mbps New Path A_D_B_C_F

Without SE Reservation Style, it is necessary 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-offs

based on several factors

End-user applications requirements Network efficiency Complexity Revenues

ur 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, Korea based on the Constrained Routing – Label Distribution Protocol (CR-LDP)

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

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NS2 Software Modules

MNS - MPLS Network Simulator

Old 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-TE module OSPF-TE module RSVP-TE module RSVP-TE module

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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>

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Simulation Scenario

GÉANT

Pan-European multi-gigabit

data communications network specifically reserved for research and education use

The GÉANT project was a

collaboration between 26 National Research and Education Networks representing 30 countries

The network connects a total
f 34 countries

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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

Target Target

To highlight the advantages of

using SE Reservation Styles

CBR Traffic Destination CBR Traffic Source

Primary Primary LSPs LSPs

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LSP Rerouting with FF Reservation Style

Destinations CBR Traffic Sources

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 random variable uniformely distributed within [0, 100 ms]

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LSP Rerouting with SE Reservation Style

Destinations CBR Traffic Sources

Reserved LSP

Back-Up LSP

PRIMARY LSP

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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 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