introduction to multi-protocol label switching (mpls) · all rightsreserved©alcatel-lucent 2006,...

All RightsReserved©Alcatel-Lucent 2006, #####

Introduction to Multi-Protocol Label

Switching (MPLS)

Matthew Bocci, Alcatel-Lucent IP Division


Agenda

History of MPLS Standardisation

MPLS Architecture

Control Plane

QoS and Traffic Engineering

Protection and Resiliency

MPLS Based Services:

�Layer 3 Virtual Private Networks

�Layer 2 Virtual Private Networks & Pseudowires


IP/MPLS in Carrier Networks

>Enhance forwarding performance of router

networks

MPLS StandardisationActivities

>Service enabling the edge

•L3 based MPLS VPN

>Business enabling the core

•MPLS attempt to enhance network

resilience

•MPLS-enhanced QoS

>Infrastructure optimization

•Traffic engineering

•Hierarchical core design

>Service convergence over MPLS

including VPLS

1996-1997

Forwarding Performance

MPLS Applications

1998

Traffic Engineering

Virtual Private Networks

1999-2000

Enhanced Network Resilience

2005+

Multi-segment PWs, Multicast in

VPLS / IPVPNs / pt-mp LSPs

2001-2004

Development of pseudowires / L2VPNs

Unified Control Plane for

Non-Packet and Packet Networks

>Pt-pt & multicast scalability


Multiprotocol Label Switching Architecture

IP P

acke

t

Labe

l Edg

e R

oute

r, L

ER

1

X

Labe

l val

ue X

adde

d by

LE

R1

Labe

l Edg

e R

oute

r, L

ER

2 LER

2 po

ps la

bel &

For

war

ds IP

Pac

ket

Labe

l Sw

itchi

ng

Rou

ter

(LS

R)

Y

Pac

ket f

orw

arde

d to

LE

R2

base

d on

Lab

el X

Labe

l X s

wap

ped

with

Y

LSP

LSP

Fo

rward

ing

Eq

uiv

ale

nce

Cla

ss (

FE

C)

e.g

. e

nd

po

int

ad

dre

ss

MP

LS

MP

LS A

rch

ite

ctu

re:

IET

F R

FC

30

31

MPLS Shim label added to each packet

Forwarding decisions are based on label, to follow a label switched path (LSP)

Runs over many link layers –SDH, Ethernet, etc

20 Bit label

EXP

TTL

S


MPLS Control Plane

Dis

trib

ute

FE

C/L

ab

el

bin

din

gs

be

twe

en

LSR

s

�Label Distribution Protocol (LDP) for non-TE LSPs

�Simple protocol that exchanges label bindings with peer LSRs

�RSVP-TE for traffic engineered LSPs

�Soft-state protocol enabling BW parameters & path to be signalled

FEC X

LER

LER

LSR

Use

lab

el

Yto

re

ach

FE

C X

Use

lab

el

Zto

re

ach

FE

C X


QoS and Traffic Engineering

Lab

el

Infe

rre

d L

SP

Drop precedence determined by EXP bits

LSRs schedule according to label context

EX

P I

nfe

rre

d L

SP

EXP bits determine CoS/ DP

LSRs schedule according to EXP bits context

RSVP-TE signals resource requirements along LSP path

Encode CoSand/or DP

20 Bit label

EXP

TTL

MPLS Label:

Control plane to determine LSP path and reserve resources along path

Classified according to

L2 or L3 criteria

Policing/Shaping applied


Protection and Resiliency

Protected LSP

Backup LSP

Path

pro

tecti

on

:

AB

Demand/2

Demand/2

Demand/2

Lo

ad

bala

ncin

g:

AB

C

LSP

Detour A-E

Detour B-E

E

D

Detour D-E

Detour C-E

Lo

cal

pro

tecti

on

:

MP

LS

pro

vid

es a

co

mm

on

pro

tect

ion

laye

r, in

dep

end

ent

of

un

der

lyin

g t

ran

spo

rt m

ech

anis

ms

Wide range of options


MPLS based Services and Virtual Private Networks

Tw

o V

PN

cla

sse

s:

Layer 3 VPNs: IP

Layer 2 VPNs:

�Virtual Private Wire Service (pt-pt Ethernet, FR, ATM, etc)

�Virtual Private LAN Service (mp-mp Ethernet)

Ser

vice

Pro

vide

r’s M

PLS

net

wor

k

P r

oute

rsP

Ero

uter

PE

rout

er

CE

rout

erC

Ero

uter

Atta

chm

ent

circ

uit

Atta

chm

ent

circ

uit

PS

N tu

nnel

IET

F R

FC

46

64

LS

P t

un

nel

s se

gre

gat

e cu

sto

mer

tra

ffic

in n

etw

ork


Border Gateway Protocol (BGP) Layer 3 VPNs

PE

PE

PE

LS

P

MP

LS

CE

CE

CE

Virt

ual R

outin

g &

For

war

ding

VR

FV

RF

VR

F

IP Service

MP-BGP* exchanges VPN membership/reachabilityinfo

Cu

sto

me

r ro

ute

s

IET

F R

FC

43

64

*MP-BGP : Multiprotocol BGP


Layer 2 VPNs

MPLS

PE

PE

Layer 2

AC

Layer 2

AC

CE

CE

Payload

(L2 protocol)

Tunnel LSP

LSP Label

Outer Label

MPLS Label Stack

Pseudowire

PW Label

Inner Label

Eth

ern

et

Fra

me

re

lay

AT

M

TD

M,

etc

LD

P s

ign

all

ing

IET

F R

FC

39

85

Pse

ud

owir

es a

re b

uild

ing

blo

cks

of

laye

r 2

VP

Ns


Virtual Private LAN Service (VPLS)

PE

PE

PE

Eth

ern

et P

W

Vir

tual

bri

dg

ing

and

fo

rwar

din

gM

PLS

Net

wor

k

�Learns MAC addresses per PW

�Forwarding based on MAC addresses

�Split-horizon forwarding for loop prevention

�Does not use Spanning Tree

�Uses hierarchy to improve scaling (H-VPLS)

Transparent L2 VPN for Ethernet

CE

CE

CE

Eth

ern

et A

C

MP

LS

tu

nn

el

IET

F R

FC

47

62


OAM in a Converged MPLS Network

PE

PE

AC

AC

CE

CE

Pseudowire

Ethernet

Frame relay

ATM

TDM, etc

LSP

Pin

g/T

race

Modeled after ICMP ping /traceroute

Bid

ire

cti

on

al

Fo

rward

ing D

ete

cti

on

(B

FD

)

Lightweight hello protocol

Vir

tual

Cir

cu

it C

on

ne

cti

vit

y

Ve

rifi

cati

on

(V

CC

V)

PW Connectivity verificationTunnel LSP

LD

P S

tatu

s Sig

nall

ing

Defect notifications

OA

M t

oo

ls f

or

each

laye

r o

f th

e co

nve

rged

net

wo

rk


Summary: Why is MPLS Important?

MPLS adds label to a packet to enable it to be switched through a PSN

�Full set of TE, OAM, and protection mechanisms

�Enhance to support both Layer 2 and Layer 3 services

Core carrier networks moving rapidly to using MPLS

�Driven by expected lower CAPEX/OPEX of a converged network and

demands of new servces

�Ethernet services need MPLS QoS/TE/Protection

�Enables Ethernet transport layer to support range of legacy (TDM, ATM…)

and new services


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introduction to multi-protocol label switching (mpls) · all rightsreserved©alcatel-lucent 2006,...

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