All RightsReserved©Alcatel-Lucent 2006, #####
Introduction to Multi-Protocol Label
Switching (MPLS)
Matthew Bocci, Alcatel-Lucent IP Division
All RightsReserved©Alcatel-Lucent 2006, #####
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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
All RightsReserved©Alcatel-Lucent 2006, #####
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
All RightsReserved©Alcatel-Lucent 2006, #####
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