MPLS is a routing technique that establishes an end-to-end path between a source and destination using labels. It builds a connection-oriented service on IP networks by using labels to set up the path in a hop-by-hop manner. MPLS makes IP routing faster by reducing the number of routing lookups and eliminates the need to run routing protocols on all devices. It is protocol independent and maps IP addresses to fixed length labels to forward traffic.

1. MULTIPROTOCOL LABEL
SWITCHING (MLPS)

2. INTRODUCTION
 Routing technique in telecommunication network
 A protocol to establish an end-to-end path from source to the
destination
 A hop-by-hop forwarding mechanism
 Use labels to set up the path
 - Require a protocol to set up the labels along the path
 It builds a connection-oriented service on the IP network

3. MULTI PROTOCOL LABEL SWITCHING
ARCHITECTURAL DIAGRAM

4. WHY MPLS?
• Makes IP routing fast
• Reduces number of routing lookups
• Eliminates to run a particular routing protocol
on all the devices

5. MPLS CHARACTERISTICS
Mechanisms to manage traffic flow of various
granularities (Flow Management)
Is independent of Layer-2 and Layer-3 protocols
Maps IP-addresses to fixed length labels
Interfaces to existing routing protocols (RSVP,OSPF)
Supports ATM, Frame-Relay and Ethernet

6. COMPONENTS
Label
Label Edge Router (LER)
Forwarding Equivalence Router(FER)
Label switching Router (LSR)
Label Distribution Protocol (LDP)

7. BENEFITS OF MPLS
1.Scalability
2.Performance
3.Better bandwidth utilization
4.Reduced network congestion
5.Better end-user experience

8. LABEL SWITCHING LOGIC
The Label Value Exp S TTL
Layer 2 Header MPLS Header IP Packet
MPLS Header :32 Bits (4 Bytes)
20 bits 3 bits 1 bit 8 bits

9. LABEL DISTRIBUTION PROTOCOL (LDP)
 MPLS routers use this to advertise labels for specific destination
IPv4
 Prefixes in the global address space to neighbour
 Does NOT control the actual routing decision made by the sending
router – that is still determined by the IGP (OSPF,IS-IS,
etc.),including supporting multipath
 Used to determine the topmost (next hop) label to be used

10. LDP CONFIGURATION
 By default it will advertise labels for all routes in the routing table
 Usually configured to only advertise the loopback addresses of
the routers
 These are the next hop addresses used in the iBGP routers to be
distributed (later)
 Once enabled all traffic to those addresses will be labelled: not
just MPLS VPN traffic.

11. DRAWBACKS OF MPLS
• Lack of Total Control – The service provider has to
configure the overall networks. And you will need to
work along with your provider in routing MPLS traffic
while using dynamic routing.
• Expensive – Since MPLS is an advanced way of
networking, it can cost you more than the Ethernet.