This document provides an introduction and overview of MPLS (Multi-Protocol Label Switching). It defines MPLS, discusses why it was developed to address limitations in IP routing, and how it works by assigning labels to packets which are then forwarded based on the label rather than long IP address lookups. Key MPLS concepts covered include label edge routers, label switch routers, label switch paths, and protocols like LDP and RSVP-TE. Applications like traffic engineering and MPLS VPNs are also mentioned.

1. Presented
by
Vidhu Baggan

2. Agenda..
Introduction
Basic Concepts
Terminology
Applications
Configuration

3. Why MPLS?
Problems with IP routing and Forwarding
Ip routing
Growth and evolution of the Internet
The need to evolve routing algorithm
The need for advanced forwarding algorithm
routing vs. forwarding (switching)
 routing: flexibility
 forwarding: price/performance
 Can we forward/switch IP packets?
Allow speed of L2 switching at L3
Router makes L3 forwarding decision based on a single field:
similar to L2 forwarding  Sppppppeeeeed

4. What is MPLS ?
Defined by IETF in 1998
It stands for Multi Protocol label Switching.
Multiprotocol-as it can apply to multiple protocols
Layer 2.5 networking protocol.

5. MPLS Working

6. In Simple Words…
Packets enter MPLS Network at a “Label Edge Router”
(LER)
LER Affix a label to packet and forwards it to the MPLS
network
Label switches in the network at each hop makes
forwarding decision solely based on label. That decision
is made based on a pre-established “Label Switch Path”
(LSP).
Labels can be integrated with existing L2 info such as
DLCI or ATM VCs.

7. MPLS VPN applications
Point to Point

8. MPLS VPN Application (contd..)
Private LAN Service

9. MultiProtocol …
Many Technologies below…

10. MPLS Layer-2.5

11. Routing and Switching
(A Comparison..)
Router : no. of IP Packets assemble while Router
Checks into Routing Table…Hence Slow
Switch :A table is maintained containing enteries of
Input Port ,Output Port,label Applied to the outgoing
packet…Hence Fast
MPLS = Best of Routing + Best of Switching

12. LSR-Label
Switch Router
Router
SWITCH

13. Terminology LSR-Label Switch Router also
known as Provider Router or
P Router
LER – Label Edge Router also
known as Provider Edge Router
or PE Router.
FEC-Forward Equivalence
Class –Set of Packets with
identical characteristics which
may be forwarded the same
way.

14. Terminology contd..
Control Plane-
responsible for collecting
and propagating the
information that will be
used later to forward
incoming packets.
Forwarding Plane/Data
plane-Takes care of label
Swapping

15. Label Edge Router:Adding a Label
IP Header
Info
Label
xx.xx.xx.xx 11
yy.yy.yy.yy 12
Ingress Router MPLS Domain
11

16. The Shim Header
Payload Data IP Layer 3 Layer 2
Shim

17. Label Switch Router:
Swapping a Label
OLD NEW
11 13
12 26
1113
Label InfoBase
MPLS Domain MPLS Domain

18. Label Switched Path
(LSP)
(established by)
LDP-Label Distribution
Protocol
Or
RSVP-TE
Resource Reservation
Protocol
(Traffic Engineering)
(LSP are Unidirectional
,the return path is a
separate LSP)

19. 19
Labels are short, fixed-length values.
417 data 288 data

20. 20
417 IP 666 IP 233 IP IPIP
POP
+
IP Lookup
PUSHSWAP SWAP
666 IP 233 IP IPIP
IP Lookup PUSHPOP SWAP
IP

21. Comparison MPLS vs VPN
MPLS VPN
Flexibility-Less
Management-only ISP
Services-MPLS have Class of
Service
Security-No built in feature
Price- It is much expensive
(Source-RCR Wireless News)
Flexibility-More
Management-Customer
may be involved.
Services- VPN don’t
necessarily have Class of
Service i.e Traffic
Prioritization
Security- Broad Range –
authentication Strategies to
Complex Encryption
Price-Less

22. Protocols
LDP- Label Distribution Protocol
Creates, maintains, and distributes the MPLS labels. It
takes networks learned via the Routing Protocol and
binds prefix information to labels.

23. Protocols contd..
RSVP-TE-Resource Reservation Protocol - Traffic
Engineering is an extension of resource reservation
Protocol (RSVP) for traffic engineering.
 It supports the reservation of resources across an IP
Network. Applications running on IP end systems can
use RSVP to indicate to other nodes the nature
(bandwidth,jitter maximum burst, and so forth) of
the packet streams they want to receive

24. Application
Traffic Engineering
Allows a network administrator to make the path
deterministic and bypass the normal routed hop-
by-hop paths.