In this First I have explained the drawbacks of traditional IP Protocols And then the Introduction of MPLS

1. BY :-
SAJIDULLAH S.KHAN
ANUJA KHODUSKAR
Dr. N A.KOLI
IJAET/Vol.II/ Issue II/April-June, 2011/150-153
Shah Vatsalkumar Nikhilkumar
M.Tech Network Engg
vatsalshah90@gmail.com
16 April 2014

2.  Drawbacks of Traditional IP Routing
 Basic MPLS Concepts
 MPLS Vs IP Over ATM
 Advantages of using MPLS TE
 MPLS Label Format
 Architecture of MPLS
 MPLS Applications
 Conclusion
16 April 20141

3.  Routing protocols are used to distribute
Layer 3 routing information
 Forwarding is based on Destination
Address only
 Routing lookups are performed on every
hop
16 April 20142

4.  Destination-based routing lookup is needed
on every hop.
 Every router may need full routing
information (more than 100,000 routes).
16 April 20143
10.1.1.110.1.1.1
Routing
lookup
Routing
lookup
Routing
lookup

5. 16 April 20144
47.1
47.247.3
D e s t O u t
4 7 .1 1
4 7 .2 2
4 7 .3 3
1
2
3
D e s t O u t
4 7 .1 1
4 7 .2 2
4 7 .3 3
D e s t O u t
4 7 .1 1
4 7 .2 2
4 7 .3 3
1
2
3
1
2
3
• Destination based forwarding tables as built by OSPF, IS-IS, RIP, etc.

6. 16 April 20145
47.1
47.247.3
IP 47.1.1.1
D e st O u t
4 7 .1 1
4 7 .2 2
4 7 .3 3
1
2
3
D e s t O u t
4 7 .1 1
4 7 .2 2
4 7 .3 3
1
2
1
2
3
IP 47.1.1.1
IP 47.1.1.1
IP 47.1.1.1
D e s t O u t
4 7 .1 1
4 7 .2 2
4 7 .3 3

7.  Most traffic goes between large sites A and B and
uses only the primary link.
 Destination-based routing does not provide any
mechanism for load balancing across unequal
paths. 16 April 20146
Primary
OC-192 link
Large Site A Large Site B
Small Site C
Backup
OC-48 link

8.  MPLS is a new forwarding mechanism in which
packets are forwarded based on labels.
 Labels may correspond to IP destination networks
(equal to traditional IP forwarding).
 Labels can also correspond to other parameters,
such as quality of service (QoS) or source address.
 MPLS was designed to support forwarding of other
protocols as well.
16 April 20147

9.  Only edge routers must perform a routing lookup.
 Core routers switch packets based on simple label
lookups and swap labels.
16 April 20148
10.1.1.110.1.1.1
Routing lookup
and
label assignment
10.0.0.0/8 
L=5
Label
swapping
L=5  L=3
Label removal
and
routing
lookup
L=3

10.  Layer 2 devices are IP-aware and run a routing
protocol.
 There is no need to manually establish virtual
circuits.
 MPLS provides a virtual full mesh topology.
16 April 20149
10.1.1.1L=5
L=3
L=1710.1.1.1
Layer 2 devices run a
Layer 3 routing protocol
and establish virtual
circuits dynamically based
on Layer 3 information

11.  Traffic can be forwarded based on other
parameters (QoS, source, ...).
 Load sharing across unequal paths can be
achieved.
16 April 201410
Primary
OC-192 link
Large Site A
Large Site B
Small Site C
Secondary
OC-48 link

12.  MPLS has two major components:
◦ Control plane—exchanges Layer 3 routing
information and labels
◦ Data plane—forwards packets based on labels
 Control plane contains complex mechanisms to
exchange routing information, such as OSPF, EIGRP,
and BGP, and to exchange labels, such as TDP, LDP,
MP-BGP, and RSVP.
Data plane has a simple forwarding engine.
Control plane maintains contents of the label-
switching table (label forwarding information base,
or LFIB).
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13. MPLS Architecture
Router functionality is divided into two major
parts: control plane and data plane
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14.  MPLS technology is intended to be used anywhere
regardless of Layer 1 media and Layer 2 protocol.
 MPLS uses a 32-bit label field that is inserted
between Layer 2 and Layer 3 headers (frame-
mode).
 MPLS over ATM uses the ATM header as the label
(cell-mode).
16 April 201413

15. MPLS uses a 32-bit label field that contains the
following information:
◦ 20-bit label
◦ 3-bit experimental field
◦ 1-bit bottom-of-stack indicator
◦ 8-bit time-to-live (TTL) field
LABEL EXP S TTL
0 19 2223 3120 24
16 April 201414

16. Frame
Header
IP Header Payload
Layer 2 Layer 3
Frame
Header
Label IP Header Payload
Layer 2 Layer 2½ Layer 3
Routing
lookup and
label
assignment
Shim Header
16 April 201415

17. IP Header
Frame
Header
IP Header Payload
Layer 2 Layer 3
Frame
Header
Label IP Header Payload
Layer 2 Layer 2½ Layer 3
ATM Adaptation
Layer 5 (AAL5) Header
Label Payload
Layer 2 Layer 2½ Layer 3
ATM
Header
Cell 1
Payload
ATM
Header
Cell 2
VPI/VCI
fields arused
for label
switching
16 April 201416

18. UDP-Hello
UDP-Hello
TCP-open
TIME
TIME
Label request
IP
Label mapping
#L2
Initialization(s)
16 April 201417

19. • LDP: Label Distribution Protocol
• LSP: Label Switched Path
• FEC: Forwarding Equivalence Class
• LSR: Label Switching Router
• LER: Label Edge Router
16 April 201418

20. •FEC = ―A subset of packets that are all treated the same way
by a router‖
•In conventional routing, a packet is assigned to a FEC at each
hop in MPLS it is only done once at the LER
Packets are destined for different address prefixes, but can
be mapped to common path
IP1
IP2
IP1
IP2
LSRLSR
LER LER
LSP
IP1 #L1
IP2 #L1
IP1 #L2
IP2 #L2
IP1 #L3
IP2 #L3
16 April 201419

21. Intf
In
Label
In
Dest Intf
Out
3 0.40 47.1 1
Intf
In
Label
In
Dest Intf
Out
Label
Out
3 0.50 47.1 1 0.40
47.1
47.247.3
1
2
3
1
2
1
2
3
3Intf
In
Dest Intf
O ut
Label
O ut
3 47.1 1 0.50
Mapping: 0.40
Request: 47.1
16 April 201420

22. Intf
In
Label
In
Dest Intf
Out
3 0.40 47.1 1
Intf
In
Label
In
Dest Intf
Out
Label
Out
3 0.50 47.1 1 0.40
47.1
47.247.3
1
2
3
1
2
1
2
3
3Intf
In
Dest Intf
O ut
Label
O ut
3 47.1 1 0.50
IP 47.1.1.1
IP 47.1.1.1
16 April 201421

23. Intf
In
Label
In
Dest Intf
Out
3 0.40 47.1 1
Intf
In
Label
In
Dest Intf
Out
Label
Out
3 0.50 47.1 1 0.40
47.1
47.247.3
1
2
3
1
2
1
2
3
3
Intf
In
D est Intf
O ut
Label
O ut
3 47.1.1 2 1.33
3 47.1 1 0.50
IP 47.1.1.1
IP 47.1.1.1
16 April 201422

24.  Label switch router (LSR) primarily forwards labeled
packets (label swapping)
 Edge LSR primarily labels IP packets and forwards
them into MPLS domain, or removes labels and
forwards IP packets out of the MPLS domain
MPLS Domain
Edge
LSR
LSR
10.1.1.1 L=3 L=5
L=43L=3120.1.1.1
10.1.1.1
20.1.1.1
16 April 201423

25. LSR performs the following three functions:
◦ Exchange routing information
◦ Exchange labels
◦ Forward packets (LSRs and edge LSRs) or cells
(ATM LSRs and ATM edge LSRs)
The first two functions are part of the control plane.
The last function is part of the data plane.
16 April 201424

26. Note: ATM edge LSRs can only forward cells.
Edge LSR
Control Plane
Data Plane
Routing Protocol
Label Distribution Protocol
Label Forwarding Table
IP Routing Table
Exchange of
routing information
Exchange of
labels
Incoming
labeled packets
Outgoing
labeled packets
IP Forwarding Table
Incoming
IP packets
Outgoing
IP packets
16 April 201425

27. MPLS is already used in many different applications:
◦ Unicast IP routing
◦ Multicast IP routing
◦ Traffic Engineering (MPLS TE)
◦ QoS
◦ Virtual private networks (MPLS VPN)
16 April 201426

28.  Improved up-time – By providing alternative
network paths
 Improved bandwidth utilization – By allowing for
multiple traffic types to traverse the network
 Reduced network congestion
 One potential drawback of MPLS is the network
administrator has to play a role in configuration of
the overall network.
16 April 201427

29.  MPLS is specifically designed for highly scalable
networks
 Multiprotocol label switching is the convergence
of connection-oriented forwarding techniques
and the Internet‘s routing protocols
 MPLS provides load balancing between unequal
paths and it‘s an advantage for MPLS Traffic
Engineering
16 April 201428

30.  Rosen, E., Viswanathan, A., and Callon, R.:
‗Multiprotocol label switching architecture‘,
RFC-3031, January 2001.
 Armitage, G.: ‗MPLS: the magic behind the myths‘,
IEEE Commun. Mag., 2000, 38, (1), pp. 124–131.
 Zhon, H., Yeh, C., and Mouftah, H.T.: ‗Dynamic
hierarchical mobile MPLS for next generation
all-IPwireless network‘. IEEE 61st Vehicular Technology
Conf., 30 May–1 June 2005, vol. 4, pp. 2230–2234
16 April 201429