8/6/2019 Copy of mpls G3 2007

1/28

8/6/2019 Copy of mpls G3 2007

2/28

8/6/2019 Copy of mpls G3 2007

3/28

MULTI PROTOCOL LABELSWITCHING

MPLS is an efficient encapsulation mechanism

Uses Labels appended to packets or transport ofdata

MPLS packets can run on other Layer 2 technologiessuch as ATM, FR, PPP, POS, Ethernet

Other Layer 2 technologies can be run over an MPLSnetwork

MPLS is a technology for delivery of IP Services

8/6/2019 Copy of mpls G3 2007

4/28

Connectionless- e.g. no QoS

Each router has to make independent

forwarding decisions based on the IP-address Large IP Header- At least 20 bytes

Routing in Network Layer

- Slower than Switching Usually designed to obtain shortest path- Do not take into account additional metrics

8/6/2019 Copy of mpls G3 2007

5/28

Complex

Expensive

Not widely adopted

8/6/2019 Copy of mpls G3 2007

6/28

Combine the forwarding algorithm used in ATM

with IP.

IP MPLS ATM

8/6/2019 Copy of mpls G3 2007

7/28

Multi Protocol Label Switching is arrangedbetween Layer 2 and Layer 3

PHYSICAL LAYER (Layer 1)(SDH/ODH/CSMA etc.)

DATA LINK LAYER (Layer 2)(ATM/FR/ETHERNET etc.)

NETWORK LAYER (Layer 3)(IP) MPLS

8/6/2019 Copy of mpls G3 2007

8/28

8/6/2019 Copy of mpls G3 2007

9/28

MPLS Header Layer 2 Header

Data

LABEL EXP TTLS

20 83 1

32 bits

A label is a short, fixed-length entity, with no internal structure.

and label does not directly encode any of the information fromthe network layer header.

Layer 3 Header

8/6/2019 Copy of mpls G3 2007

10/28

LABLE - Actual lable

EXP - Experimented use

BS - Bottom of stack use

TTL - Time to Live

LABEL EXP LS

20 83 1

32 bits

8/6/2019 Copy of mpls G3 2007

11/28

MPLS-capable routers might need more thanone label on top of the packet to route that packet through the MPLS network. This is done

by packing the labels into a stack. The first labelin the stack is called the top label, and the lastlabel is called the bottom label. In between,you can have any number of labels.

8/6/2019 Copy of mpls G3 2007

12/28

LABEL EXP LS

LABEL EXP LS

LABEL EXP LS....

8/6/2019 Copy of mpls G3 2007

13/28

A path is established before the data transmissionstarts.

A path is a representation of a FEC.

LSP

8/6/2019 Copy of mpls G3 2007

14/28

LABLE EDGE ROUTER (LER)

Resides at the edge of an MPLS network and

assigns and removes the labels from the packets.

Support multiple ports connected to dissimilarnetworks (such as frame relay, ATM, and Ethernet).

8/6/2019 Copy of mpls G3 2007

15/28

LABLE SWITCHING ROUTER (LSR)

Is a high speed router in the core on an MPLS

network.

ATM switches can be used as LSRs withoutchanging their hardware. Label switching is

equivalent to VP/VC switching.

8/6/2019 Copy of mpls G3 2007

16/28

Forwardingequivalencyclass (FEC)

A FEC is a group of layer-3 packets that are

forwarded in the same manner. All packets in this group follow the same network

path and have the same prioritization. Packetswithin an FEC may have different layer-3 header

information. However, to simply make a forwarding decision,

these packets are indistinguishable.

8/6/2019 Copy of mpls G3 2007

17/28

8/6/2019 Copy of mpls G3 2007

18/28

Before traffic is forwarded on the MPLS network, the PErouters first establish LSPs through the MPLS network toremote PE routers.

I need a label for LSR A

Use label 27

Request:

Response:

8/6/2019 Copy of mpls G3 2007

19/28

8/6/2019 Copy of mpls G3 2007

20/28

At the egress PE, the last MPLS label is removed and thepacket is forwarded by traditional routing mechanisms.

The packet proceeds to the destination CE and into thecustomers network.

8/6/2019 Copy of mpls G3 2007

21/28

8/6/2019 Copy of mpls G3 2007

22/28

8/6/2019 Copy of mpls G3 2007

23/28

The use of one unified networkinfrastructure

Better IP over ATM integration

Border Gateway Protocol (BGP)-free core

The peer-to-peer model for MPLS VPN

Optimal traffic flow

Traffic engineering

8/6/2019 Copy of mpls G3 2007

24/28

8/6/2019 Copy of mpls G3 2007

25/28

Enables a single converged network to supportboth new and legacy services

Enables traffic engineering, help squeeze more

data into available bandwidth. Supports the delivery of services with Quality of

Service (QoS) guarantees.

Reduces router processing

Provides the appropriate level of security

8/6/2019 Copy of mpls G3 2007

26/28

8/6/2019 Copy of mpls G3 2007

27/28

Whowilluse MPLS? Large-scale data networks used by Enterprises, Carriers

and ISPs.

MPLS labled Multicast

Why MPLS? Delivers high speed L2 (really Label) switching at low

cost vs. traditional L3 routing

Provides Traffic Engineering - allows the user to directtraffic based on network utilization and demand.

Ease of provisioning QoS

Support for VPNs

8/6/2019 Copy of mpls G3 2007

28/28

As network administrator I can takedown the network with one keystroke. It's

just like being a doctor but without gettinggooky stuff on my paws

Scott Adams ("Dogbert")