Part I: Routing Architecture in the DiffServ MPLS Networks

S-38.130 Licentiate course on Telecommunications Technology (4+1+3 cr.)

Course Topic Spring 2000: Routing Algorithms in the DiffServ MPLS Networks

Introduction II:

Routing Architecture in the DiffServ MPLS Networks Performance Analysis of Routing AlgorithmsIntroduction to MaRS, QRS and EQRS



Part I: Routing Architecture in the DiffServ MPLS Networks

• Differentiated Service• Multi-Protocol Label Switch• Traffic Engineering in the DiffServ MPLS

Networks• Routing in the DiffServ MPLS Networks



Differentiated Service

Figure 1 Differentiated Service Architecture

Features:

- PHB

- Scalability



Multi-Protocol Label Switch

• Features: – Connection-oriented

– Fast Forwarding

– Label Stack

• Advantages– Traffic Engineering

• Applications– Virtual Private Network

Figure 2 MPLS VPN Networks



Traffic Engineering in the DiffServ MPLS Networks

• Path Management: – Signaling Protocols:

- CR-LDP and Extended RSVP

– Constraint-based Routing • Traffic Assignment• Network State Information Dissemination• Network Management

Figure 3 Interaction of traffic engineering components in an MPLS network



Signaling Protocols

CR-LDP ERSVP

Transportmechanism

On TCP (reliable) Raw IP packets (unreliable)

Statemanagement

Hard state Soft state; needs per-flowrefresh management

BaseArchitecture

Based on LDP Based on RSVP

Table 1 Comparisons between CR-LDP and ERSVP



Routing in the DiffServ MPLS Networks

• Constraint-based Routing• Route Pinning• Rerouting

– Fast Rerouting

– Optimized Rerouting

– Rerouting to an alternate path

Figure 4 Rerouting



Part II: Performance Analysis of Routing Algorithms

• Performance Metrics– Computation Complexity

– Stability

– Scalability

– Feasibility

• Analyzing Methods – Theoretical Analysis

– Computer Simulation

– Experimental Implementation



Part III: Introduction to MaRS, QRS and EQRS

• Structure• Capabilities Comparison• QRS• EQRS



Structure

• Simulation Engine• User Interface• Components

Figure 5 An example target system



Capabilities Comparison

EQRS QRS MaRS

Resource Reservation ERSVP RSVP

Resource Management X X

Network Management NOMP Policy ControL

Routing QOSPF, ExBF, SPF QOPSF SPF, ExBF

DiffServ Services AF, EF

MPLS X

Realtime Traffic X X

Support for Multi-domains X

Explicit route withoutresource reservation

X

Traffic engineeringClassifier, marker,

dropperClassifier

Forwarding Label forwarding X X

Queuing CBQ with priority CBQ with Priority

Dropper WRED

Table 2 Comparisons among MaRS, QRS and EQRS



QRS: General Design

Features:

- Simplified RSVP -Realtime Traffic

- QOSPF -CBQ

Figure 6 General design and interactions between components of QRS



QRS: QOSPF

Features:

- Two On-demand computation algorithms

- Two link state update algorithms

Figure 7 Design of QOSPF in QRS



QRS: Traffic Scheduling

Features:

- CBQ

- Three class levels

Figure 8 Traffic processing and scheduling of Node and Link in QRS



QRS: Some Results (1)

Figure 9 Simulation 1: Tree Topology

0

1

2

3

4

5

6

0 2 4 6 8 10Time (s)

Thr

ough

put(

Mbi

ts/s

) RTHRTLBETOTAL

Figure 10 Throughput vs. time in Simulation 1




2*2 3*3 4*4 5*5

10ms 0.53s 2.38s 2.27s 3.82s

50ms 0.42s 2.04s 1.89s 3.37s

100ms 0.38s 1.33s 1.59s 3.12s

500ms 0.31s 0.68s 0.96s 1.65s

Figure 11 Simulation 2: Matrix Topology

Table 3 Running Time in Simulation 2




Figure 12 Simulation 3: NSFNET Backbone

0

0,5

1

1,5

2

2,5

0 2 4 6 8 10

Time (s)

Thro

ugh

put

(Mit

s/s)

C-A'

C-C'

Figure 13 Throughput vs. time in Simulation 3



EQRS: General Design

Features:

-DiffServ -MPLS -Extended RSVP

-NOMP -Multiple domains -With or without resource reserved

Figure 14 General design and interactions between components of EQRS



EQRS: Services

AFEF

AF1 AF2 AF3 AF4BE

Workload ERSVP, Route Realtime TrafficFTP, Telnet,

Simple Traffic

RouteSelection

ERSVP: Flow TableRoute: Routing Table

Flow Table Routing Table

Priority High Low

Table 4 Workload and DS services in EQRS



EQRS: Multiple Domains

Figure 15 Hierarchical Domains

Figure 16 A network with hierarchical domains



EQRS: NOMP

Functions:

-Resource provision -Explicit route assignment

-Network maintance

Figure 17 Structure of NOMP



EQRS: ERSVP

• Extensions:– Two new objects:

• LABEL_REQUEST

• LABEL

– As signaling protocol



EQRS: Traffic Scheduling

Notes:

-Edge node: Classifier and marker

-All nodes: Dropper and Queuer

Figure 18 Dropper and Querer in EQRS

Part I: Routing Architecture in the DiffServ MPLS Networks

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