1 6 Ip Routing Voip Mpls 3

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Routing Basics

Routing is moving packets across internetwork from source to destination.

Routing involves two basic activities:-

Determination of optimal path to thedestination.

Transport or delivery of packets to the

destination.


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Routing Methods

Next hop routing:

In this method the routing table holds only theaddress of the next hop, instead of holdingcomplete route information.

Network Specific Routing:

Instead of having an entry for every hostconnected to the same physical network, onlyone entry to define the address of the network.

Host Specific Routing:

The host address is given in the routing table.

Default Routing: Instead of listing all networks in the entire

Internet a host can just have one entry called thedefault address.


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Routing Basics

When looking for the route, the router must first

check for direct delivery, then host specificdelivery, then network specific delivery andfinally default delivery.

A host or a router keeps a routing table, with

an entry for each destination, to route IPpackets.

The routing table may be

Static

Dynamic


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Routing Algorithms

Routing algorithms can be classified by type.

Static versus dynamic

Single-path versus multipath

Flat versus hierarchical

Host-intelligent versus router-intelligent

Intradomain versus interdomain

Link-state versus distance vector


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Static Routing

Static routing table mappings are establishedmanually by the network administrator.

Static routing system cannot react to network

changes. They are not suitable for Todays large

Internetwork.


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Dynamic routing

By using Routing protocol the routers can

automatically update any change in the routeDynamically. This is known as Dynamicrouting.

In large WAN with multiple links betweennetworks routers perform more effectivelywhen they under stand how the network islinked.



Dynamic routing

Routers do this by exchanging information

with other Routers.

As a result Routers create Routing Table thatshows the best path between the various

links.



Routing Basics

Wide variety of Routing P rotocols can be found

Some are P roprietary or Single vendor fortheir own products.

Others are open that have been standardisedby official sanctioning Agencies.

Among the P roprietary are

IPX IGRP

Open Protocols

RIP

OSPF Intermediate System to Intermediate System



Routing Algorithms

All dynamic routing protocols are based on somealgorithms.

Algorithms must be able to quickly determine theNetwork topology.

This process is called Convergence. Convergence must take place rapidly.

Each algorithm has a different impact on Networkand Routers.

Routing algorithms use a variety of Metricsthat affect calculation of Optimal Routes.



Commonly used algorithms are

Distance Vector P rotocol

Link Status P rotocol



When there are multiple routes to the samedestination, a router must have a mechanism forcalculating the best path.

A metric is a variable assigned to a routes as ameans of ranking them from best to worst or from

most preferred to least preferred. Different routing protocols use different metrics

and sometimes multiple metrics.

Path Determination



Metrics

The following are the metrics used.

Hop Count Bandwidth

Load

Delay

Reliability Cost



Distance Vector Protocol

In Distance Vector routing protocol each routerskeeps a routing table of its perspective of thenetwork.

The distance vector protocol is also known as

Ford-Fulkerson routing algorithm named after theinventors.

Each routers takes the routing information passedto it, adds one hop to the route and passes theupdated information to the next.



Distance Vector Protocol

Routers create a network map by communicating ina periodic and progressive sequence with otherrouters.

This information exchange helps them determinethe scope of their network in a series of router hops

that reveals more information about the network.

When the router is started it knows only thenetworks it is connected directly.

Then advertises information about its immediate

connections to the other routers directly connected.

The Distance vector routing protocol uses secondhand information from their neighbor.



Link Status Protocol

Based on Shortest Path F irst or Dijkstra Algorithm.

Sending of link state advertisements (LSAs) to allother routers within the same hierarchical area.

SPF routers send link-state data to all routers.

The routers perform two tasks

First they use the link-state data to build acomplete table of router and networkconnections.

Then each router calculates the optimal path toeach link.

When a router detects changes in the state of itsdirect link the router broadcast the change to allothers through a process called flooding.



Routing Protocols

Routing protocols are divided into

Interior Gateway Routing Protocol(IGP)

Exterior Gateway Routing P rotocol(EGP)

i l



Routing Protocols



Interior Gateway Protocol

Interior Gateway P rotocol are used within anAutonomous System to dynamically determinethe best route.

They are based on

Distance Vector Algorithm

Routing Information P rotocol (RIP )Routing Information P rotocol 2 (RIP 2)

Link Status Algorithm

Open Shortest path first(OSPF)

Internet Gateway Routing Protocol (IGRP)Enhanced IGRP

Integrated Intermediate System toIntermediate System

i l



Exterior Gateway Protocol

Exterior Gateway protocol is known as interdomain Protocol.

Used to exchange routing information betweendifferent Autonomous systems.

E i G P l




Exterior gateway protocols require the following

three sets of information before routing canbegin.

A list of neighbor (or Peer) routers with whichto exchange routing information.

A list of Networks to advertise as directlyreachable.

The Autonomous system number of the LocalRouter.

E i G P l




Border Gateway P rotocol (BGP ) Border Gateway P rotocol version4 (BGP 4)

R ti I f ti P t l



Routing Information Protocol RIP is a Distance Vector P rotocol.

Each router automatically sends a copy of its

routing table to each of its neighbors every 30sec.

If the updates are not received with in 180 Secthen the route is declared as unreachable .

RIP routing table entries contain

the destination (Network or Host or Default)

Metric indicating the Distance

Interface to use.

Gateway to use.

Timer, reset whenever the entry is updated.

R ti I f ti P t l



Routing Information Protocol

RIP maintains only the best route to a destination. When a new information provides a better route this

will replace old route information.

RIP uses single routing metric (Hop count).

RIP F t


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RIP Features Hop-count:

Maximum 15 hops. Beyond that unreachable.

Split Horizon: Never send the information about a router

back in the same direction. (Called reverseroute)

Split Horizon with poisoned reverse:

Advertises reverse routes but with anunreachable metric.

Triggered Updates

If metric changes send out an update (F lash

update) Hold-Downs:

Prevents regular update for a route that hasgone bad.

P bl ith RIP


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Problems with RIP

Slow convergence

Not suitable for Larger Network. (Hop count is15)

Do not Support variable Length Subnet Mask.

Only uses one path (Only one entry per

destination)No provision for load balancing.

HOP count are only a crude metric - does notproduce optimal route.

Max data gram size is 512 byte.

RIP i 2


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RIP version 2

Support VLSM

Routing Tags to supports EGP

Support multicasting.

I t i G t R ti P t l


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Interior Gateway Routing Protocol

Developed by CISCO in the mid 1980s.

IGRP uses a combination of metrics

Internetwork Delay

Bandwidth (1200 bps to 10 gigabits)

ReliabilityLoad (Value 1 to 255)

E h d IGRP


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Enhanced IGRP

With Software Release 9.21 Cisco introducedEIGRP.

It combines advantage of Link status with theDistance vector protocols.

EIGRP incorporates the Diffusing UpdateAlgorithm.

Open Shortest Path First


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Introduced in 1989

Uses Link State algorithm. Much lower protocol traffic overhead.

Elimination of count to infinity problem.

Using cost as metric, Metric can be as large as65535.

Support VLSM

Support a much larger internetwork than RIP .



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Each Router builds a database of the Network.

Exchanges only when tables are updated Provides Load balancing.

Multiple routes to a single destination.

Looping is not formed since each router has thecomplete information.

Faster convergence.

Sending link State advertisement to all otherrouters.

Border Gateway Protocol


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Border Gateway Routing Protocol is an Exterior RoutingProtocol.

Used for Exchanging network reacheability informationbetween AS.

Each AS designates one or more routers that runs BGP.

BGP routers in each AS are linked to BGP routers in oneor more AS.



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Routing information are stored as a set ofRouting Information Bases.

This information is exchanged between BGProuters, and propagated to the entire network.

This enables each AS to find paths to eachother network in other AS.

Presently BGPv4 is used as the inter domainrouting protocol.

Topology


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Topology

BGP supports an arbitrary topology of AS s

An AS must have one router running BGP , butcan have more BGP routers.

It is possible to use BGP routers to communicate

between BGP routers with in the same AS.

Topology


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Topology

BGP can handle a set of AS connected

In a full mesh topology

Partial mesh

A chain of AS linked one to the next

Any other configuration

BGP can handle changes to topology that mayoccur.


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Whats VoIP?


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What s VoIP?

VoIP is the ability to make telephone calls over

IP -based data networks with a suitable quality

of service and cost benefit.

Motivations for VoIP


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Motivations for VoIP

Demand for Multimedia communication

Demand for integration of Voice and Data networks

Cost Reduction in long distance telephone calls

Motivations and Benefits of VoIP


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Motivations and Benefits of VoIP

Low Cost of public Internet Long distance call for the price of local PSTN

Integration of voice and data applications

Internetaware telephones

Intranet Telephony

Trivial implementation of existing services

Video conferencing

How to VoIP?


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How to VoIP?

AnalogDigital Voice

Compression to less than32Kbps

Transfers through Routers, LAN

Switches etc, using their P rotocols

Voice To/From IP


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Voice To/From IP

Analog

Digital

Voice

CODEC: Analog to Dig i ta l

Compress

Create Voice Datagram

Add Header

(RTP, UDP, IP, etc)

Network

Voice To/From IP


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Voice To/From IP

Digital

Analog

Process Header

Re-sequence and

Buffer Delay

Decompress

CODE C: Digital to Analog

Network

Voice

Configuration Options


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Configuration Options

Telephone-to-Telephone

PC to PC


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PC-to-PC

Telephone-to-


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Telephone toPC

ISO Reference Model and VoIP


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ISO Reference Model and VoIPStandards

ISO Protocol layer Protocols and standardsP resentation Codecs / Applications

Session H.323 / SIP / MGCP

Transport RTP / TCP / UDP

Network IP

Link FR, ATM, E thernet, P P P,etc.

oIP Standards


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oIP Standards

ITUH.323

IETF

Session Initiation Protocol (SIP )

Media Gateway Control P rotocol

(MGCP)

.323 Entities


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.323 Entities

LAN

Terminal

Terminal

Gateway

Gatekeeper

MCU

Terminal


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Terminal

Endpoint on a LAN Supports real-time, 2-way communications

with another H.323 entity

Must support:

Voice - audio codecsSignaling and setup

Optional support:

Video

Data

Gateway


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Gateway

Interface between the LAN and the circuitswitched network

Translates communication procedures and formats

between networks

Call setup and clearing

Compression and packetization

of voice

Example: IP /PSTN gateway

Gatekeeper


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Gatekeeper

The most vital component of H.323 system Manages a zone (a collection of H.323 devices)

Usually one gatekeeper per zone; alternategatekeeper might exist for backup and loadbalancing

Functionalities: Address Translation

Call authorization and signaling

Bandwidth Management

Call Management

Multi-point Control Unit (MCU)


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Multi point Control Unit (MCU)

Endpoint that supports conferences between

3 or more endpoints

Can be stand-alone device (e.g., P C) or

integrated into a gateway, gatekeeper or

terminal

Simple VoIP Call


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Simple

Caller Number : 785-537-2736

Called Number : 410-944-511

ITS P Number : 1-888-745-2654

Local Loop Trunk

785-537-2736

Local S witch

Gateway

1-888-745-2654

Caller dials ITS P toll free number : 1-888-745-2654Caller gets connected to VoIP gateway of IT S P

Simple VoIP Call


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Simple VoIP Call

785-537-2736

Local Switch

Gateway

1-888-745-

2654

What is the IP address of the destination gateway for 410-944-

2511?-LRQ

The IP address of the destination gateway is 154.23.78.345. LCF

May I call the IP address? AR Q

You may use XX Kbps bandwidth - ACF

Gatekeeper

ARQ

ACF

LRQ

LCF

Simple VoIP Call


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p

785-537-2736

Local Switch

Gateway

1-888-745-

2654The setup message cons ists of

Originator gateway IP address (129.130.10.123) DestinationGateway IP address (154.23.78.345)

C aller-number (785-537-2736) C alled-number(410-944-2511)

H.245 request: OpenLogicalC hannelF orAudio

Gatekeeper

Connect H.225/Q.931/H.245

Destination

Gateway

Simple VoIP Call


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p

785-537-2736

Local Switch

Gateway

1-888-745-

2654

Destination gateway makes a request to the gatekeeper to

accept the call from the originator May I call the originator gateway IP address? AR Q

Yes , You may use XX Kbps bandwidth - ACF

Gatekeeper

ARQ

ACF

Destination

Gateway

Simple VoIP Call


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p

785-537-2736

Local Switch

Gateway

1-888-745-

2654

Destination gateway sends a connect confirm message.

Gatekeeper

Connect H.225/Q.931/H.245

Destination

Gateway

Simple VoIP Call


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p

Local Switch

Gateway

Gatekeeper

Local Switch

Gateway

Destination Gateway establishes PSTN

connection with PSTN circuit switch andH.245 audio channel

Caller will hear the ringer tonegenerated by the destination switch

QoS Issues


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Q

Delay For high quality voice, oneway latency must not begreater than 150ms. Delaygreater than 50ms leads toecho and talker overlap.

J itter Variation in inter-packet

arrival time. The solutionto this problem is tointroduce jitter buffers.

P acket Loss Loss in excess of 5-10%causes significantdegradation in voice

quality.

Re-ordering P ackets may arrive out of order and this leads togarbled speech.

Voice enabled Software


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NetMeeting, WindowsMessenger (Microsoft)

Net2Phone CommCenter (Net2Phone)

DialpadChameleon (DialPad)

eDial Desktop Voice Conferencing System

(eDial)

IP Communications (WorldCom)


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What is MPLS ?


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Multi protocol label switching (MP LS) is a versatile

solution to address the problems faced by

present day IP networks

Speed

Scalability

Quality of service (QoS)

Traffic engineering

What is MPLS ?


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MP LS is a new packet forwarding protocol which

works at layer 2.

Unlike conventional routing of IP Datagrams at

layer 3, MP LS follows the principle of switching of

IP Datagrams at layer 2 (Data link layer).

Thus over all forwarding speed fastens up

Why MPLS ?


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y

The evolution of MPLS has come out with the idea to

address certain network associated problems

Layer 3, network layer routing scalability

Leverage existing ATM hardware

Ultra fast forwarding

IP Traffic E ngineering (Constraint-based Routing )

VP N (Controllable tunneling mechanism)

Introduction


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MP LS performs the following functions

Specifies mechanism to manage traffic flows

Provides a means to map IP address to simple,

fixed length labels

Remains independent of layer-2 and layer-3

protocols

Supports the IP, ATM and Frame relay layer-2

protocols

Interfaces to existing routing protocols such as

RIP and OSPF

Introduction


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In conventional packet forwarding every router

opens the IP datagram and looks at IP header to

find out destination IP address and then with the

help of its routing table takes independent decision

to forward the packet.

Handling a bulky IP header and then reconstructing

it before forwarding to next router compromises

with the speed of the entire operation.

This operation takes place at layer 3

Routing, Switching and Forwarding


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Routing The process of setting up routes to

understand the next hop a packet should taketowards its destination between networks. Arouter is the device that sets up routing table andoperates on layer 3 packet header to analyze the

best forwarding pathSwitching The knowledge of directing the

forwarding process to choose the correct outputport. A switch is a device that operates on layer

2 header information to direct the forwardingprocess

Forwarding The process of receiving a packet onan input port and sending it out through anoutput port

MPLS


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MP LS works at layer 2.

Unlike conventional forwarding of IP packets,

MPLS classifies each packet and attaches a

small label with IP datagrams based onFEC(Forwarding Equivalence Class) of that

packet at the ingress point of MPLS network.

Subsequent routers only look at the label and

route the packet after swapping the label with a

new one.

MPLS


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Label Swapping

Connection table maintains mappings

Exact match lookup

Input (port, label) determines: Label operation

Output (port, label)

Same forwarding algorithm used in Frame Relay and ATM

Port 1

Port 3

Port 2

Port 4

Connection TableIn

(port, label)Out

(port, label)

(1, 22)

(1, 24)

(1, 25)

(2, 23)

(2, 17)

(3, 17)

(4, 19)

(3, 12)

LabelOperation

Swap

Swap

Swap

Swap

25IP

19IP

MPLS CONCEPT AND TERMINOLOGY


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At Edge:- classify packets- label them

In Core:

- forward using labels(as opposed to IP addr)- label indicates service

class and destination

LER Label Edge Router L IB Label Information BaseLSR Label S witch Router LDP Label DistributionProtocolLSP Label Switch P ath CR-LDP Constraint routingLDPF EC F orwarding E quivalence Class TE -RS VP Traffic Engineered RS VP

ROUTE AT EDGE, SWITCH IN


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IP ForwardingLABEL SWITCHINGIP Forwarding

IP IP #L1 IP #L2 IP #L3 IP

Routing RoutingSwitching

COREEDGE

CORE

MPLS Terminology


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Label-Switched Path (LSP )

Simplex L2 tunnel across a network

Concatenation of one or more label switchedhops

Bangalore

NewDelhi

LSP

MPLS Terminology


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Label-Switching Router (LSR )

Forwards MPLS packets using label-switching

Capable of forwarding native IP packets

Executes one or more IP routing protocols

Participates in MPLS control protocols

Bangalore

NewDelhi

LSP

LSR

LSR

LSRLSR

MPLS Terminology


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Bangalore

NewDelhi

LSP

Ingress LSR (head-end LSR )

Examines inbound IP packets and assigns them to anFEC

Generates MPLS header and assigns initial label Transit LS R

Forwards MPLS packets using label swapping

Egress LSR (ta il-end LSR)

Removes the MP LS header

IngressLSR Transit

LSR TransitLSR

Egress

LSR

LSR (Label Switching Router)


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The devices that participate in the MP LS

protocol mechanisms can be classified into

Label edge routers (LERs) and Label

switching routers (LSRs)

An LSR is a high speed router in the core of

an MPLS network that participates in the

establishment of LSPs using the appropriatelabel signalling protocols and high speed

switching of the data traffic based on the

established paths.

LER (Label Edge Router)


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An LER is a router that operates at the edgeof the access network and MP LS network

LERs support multiple ports connected todissimilar networks

LERs forward the traffic on to the MP LSnetwork after establishing label SwitchedPaths, using the signalling protocol at theingress and distributing the traffic back to the

access network at egressThe LER plays a very important role in the

assignment and removal of labels

Forward Equivalence Class


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FEC = A subset of packets that are all

treated the same way by a router

The concept of FECs provides for a greatdeal of flexibility and scalability

In conventional routing, a packet is assignedto a FEC at each hop (i.e. L3 look-up)

In MP LS it is done only once at the ingressrouter.

MPLS Label Format


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FieldsLabelExperimental (CoS)Stacking bit

Time to liveIP packet is encapsulated by ingress LSRIP packet is de-encapsulated by egress LSR

TTLLabel (20-bits) CoS S

IP Packet

32-bits

L2 Header MPLS Header

Separation of Control P lane and ForwardingPlane


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Plane

Routing Protocol

Forwarding Table

InterfaceInterface

Packet Processing

Control Plane

Forwarding Plane

Switching Fabric

Data Path

MPLS layer 2Switching

Implemented In Software

Implemented In Hardware

(Slow)

(Fast)

By completely separating the control component from the F orwardingcomponent each component can be Independently Developed andmodified T he only requirement is that control component continue tocommunicate with forwarding component by managing the P acketforwarding Table. By deploying the extremely s imple label swappingalgorithms can P rovide extended forwarding capabilities.

Data Path

ConventionalLayer 3 Routing

Routing Updates

Routing Table

The fast path and slow path


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Control Path

Forwarding Path

Software

Hardware

Control Path

Forwarding Path

Software

Hardware

Data Data Data

ControlSlow Path

Fast Path

Router A Router B

The Traffic that flows into the network can be of two types :

Control traffic, which includes routing and management information,

Data traffic Which is, well , everything else.

The data traffic follows the fast path which is realized in hardware.

Any time network device encounters a packet that is not data, the packetis sent up to control path processing. These packets are processed moreslowly because they need to be examined by so ftware.

MPLS Model


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Layer 2.5 Technology is another phrase that is often

used to describe what MP LS is.

MP LS is depicted as a new shim layer that has interposed

itself between the network and data link layer

Layer 4-7 (Transport, sess ion P resentation, application)

Layer 3 (Network)Layer 2.5 (?) (MP LS )

Layer 2 (Data link )

Layer 1 (P hysical)

MPLS BUILT ON STANDARD IPD t O t


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Dest Out

47.1 1

47.2 2

47.3 3

Dest Out

47.1 1

47.2 2

47.3 3

Dest Out

47.1 1

47.2 2

47.3 3

Des t i n a t i o n b a se d f o r w a r d i n g t a b l e s a s b u i l t b y O SP F, IS- IS , R IP,

31

1

23

12

3

47.1

47.3

47.2

2

IP FORWARDING USED BYHOP BY HOP CONTROL


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HOP-BY-HOP CONTROL

47.1

IP 47.1.1.1

Dest Out

47.1 1

47.2 2

47.3 3

Dest Out

47.1 1

47.2 2

47.3 3

1IP 47.1.1.1

IP 47.1.1.1IP 47.1.1.1

Dest Out

47.1 1

47.2 2

47.3 3

123

23

2

1

3

47.2

47.3

MPLS Label Distribution


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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

Intf

In

Dest Intf

Out

Label

Out3 47.1 1 0.50 Mapping: 0.40

Request: 47.1

MPLS

Domain

3 12

1

23

3

2

1 47.1

47.3

47.2

Label Switched Path (LSP)


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47.1

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

123

2

1

23

3Intf

In

Dest Intf

Out

Label

Out3 47.1 1 0.50

IP 47.1.1.1

MPLS

Domain

1

IP 47.1.1.1

47.2

47.3

Label Distribution


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MP LS architecture uses various methods ofsignalling for label distribution

LDP- maps unicast destinations into labels

RSVP,CR-LDP-used for traffic engineeringand resource reservation along with labeldistribution to upstream routers

Protocol-independent multicast(P IM)-used for

multicast states label mapping

BGP-external labels(VP N)

Label Spaces


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The Labels used by an LSR for FEC-Label

bindings are categorized as follows :Per Pla t f or m -The label Values are unique

across the whole LSR. The labels areallocated from a common pool. No two labels

distributed on different interfaces have thesame Value.

Per In ter f ace- The Label ranges areassociated with interfaces. Multiple label

pools are defined for interfaces, and labelsprovided on those interfaces are allocatedfrom the separate pools. The label valuesprovided on different interfaces could be thesame.


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MPLS Operation


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1 a . E x i s t i n g r o u t i n g p r o t o c o l s ( e. g . O S PF, I S -I S )

e s t ab l i s h r e ac h a b i l i t y t o d e s t i n a t i o n n e t w o r k s

1 b . L ab e l D i s t r i b u t i o n P r o t o c o l ( L DP )

e s t ab l i s h e s l a b el t o d e s t i n a t i o n

n e t w o r k m a p p i n g s .

2 . I n g r e s s E d g e L S R

r e c e i v e s p a c k e t , p e r f o r m s

L a y e r 3 l o o k u p a n d

l a b e l s p a c k e t s

3 . L S R s w i t c h e s

p ac k e t s u s i n g

l a b el s w a p p i n g

4 . E d g e L S R a t

e g r e s s

r e m o v e s l a b e l

a n d d e l i v e r s

p ac k e t

MPLS Forwarding Example


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134.5.1.5

200.3.2.7

1 2

200.3.2.1

134.5.6.1

Ingress Routing Table

Destination Next Hop

134.5/16

200.3.2/24

(2, 84)

(3, 99)

MPLS TableIn Out

(1, 99) (2, 56)

MPLS TableIn Out

(3, 56) (5, 0)

Destination

Egress Routing TableNext Hop

134.5/16

200.3.2/24

134.5.6.1

200.3.2.1

200.3.2.7

MPLS Table

In Out

(2, 84) (6, 0)

200.3.2.7

3 5

2

3

2 6

Signalling Mechanism


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Label Request Using this mechanism, anLSR requests a label from its downstreamneighbour so that it can bind to a specific FEC.

This mechanism can be employed down the

chain of LSRs up untill the egress LER. Label Mapping In response to a label

request, a downstream LSR will send a label tothe upstream initiator using the label mapping

mechanism.

Label Distribution Protocol (LDP)


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The LDP is a new protocol for the label binding informationto LS Rs in an MPLS network. It is used to map FECs to

labels, which in turn, create LSPs. LDP sessions are established between LDP peers in MPLS

network

LDP does not provide traffic engineering capability. Thepeers exchange the following type of LDP messages:

D is c o v e r y m e s s a g es announce and maintain the presence of anLS R in a network

S es s i o n m e s s a g e s establish, maintain, and terminate sessionbetween LDP peers

A d ver t i s em en t m es s ag es Create, change and delete labelmapping for FECs

N o t i f i c a t i o n m e s s ag e s P rovide advisory information andsignal error information

Label Distribution Protocol (LDP)


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Label Request for FEC

10.0.0.0

Labels assigned by downstream peer

Benefits

Labels are not piggybacked on routingprotocols

Limitations

LSPs follow the conventional IGP path

Does not support explicit routing

UpstreamLDP peer

DownstreamLDP peer

LSR

325413

Net: 10.0.0.0Label: 52

(3, 29)

Net: 10.0.0.0Label: 29

MPLS Table

In Out

(2, 52)

MPLS Table

In Out

(1, 17)

MPLS Table

In Out

(5, 52)

Receiveoutgoing

label(4, 17)

Net: 10.0.0.0Label: 17

Advertiseincoming

label(3, 35)

RSVP-Resource Reservation Protocol


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This protocol was originally developed for

providing quality of service in IP networks.Some extensions has been done in this protocol

to carry the label request with path message indown stream directions and label mapping with

reservation message in upstream directionsalong with resource reservation message.

It is a soft state protocol as it depends onperiodical path and reservation refreshmessages.

RSVP provides traffic Engineering Capability inMP LS networks.

RSVP Resource Reservation Protocol


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Senders

Path Message

Resv MessageReceivers(Data Path)


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Traffic Engineering


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Traffic Engineering is the process of controlling

how traffic flows through ones network so as to

optimise resource utilization and network

performance.

Traffic engineering in Internet is needed mainly

because current IGPs always use the shortest

paths to forward traffic. Using shortest paths

conserves network resources,but it may also

cause the following problems :

The shortest path from different sources overlap

at some links, causing congestion on those links.

Traffic Engineering


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The traffic from a source to a destination exceeds

the capacity of the shortest path, while a longer

path between these two routers is under-utilized.

Traffic engineering does not necessarily select

the shortest path between two devices.

This way, the less exposed or less-used network

segment can be used and differentiated services

can be provided


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QoS


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Different types of service quality can be

provided for various types of traffic that is

traversing the Internet like data, packetized

voice, and video.

An MPLS QoS application is actually derived

from applying general QoS techniques to the

integrated services (IntServ) frame work and

Diffserv building block model of MP LS.

QoS


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General Qos is the ability to guarantee at

some quantifiable level that network nodes or

application can provide a satisfactory level of

performance and reliability.

QoS requires every element from the start of

an application flow to its completion to be

aware and respond to QoS requirements

The QoS Spectrum


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I n t e r n e t Today

TO S B a s e d

R el a t i v e Pr i o r i t i e s

P r o v i s i o n e d

C o n n e c t i o n s

En d - t o - En d Ca l l - b y - Ca l l

G u a r a n t e e d

GuaranteedConnections

Priority

No Guarantee

BasicAccess/E-mail

Browsing P remiumAccess

Real TimeVoice/Video

ApplicationSpecified

QoS Level

Application Type

DiffServ

Int Serv

QoS in MPLS


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Integrated Services (IntServ)

The IntServ framework deals with resourcereservation where network resources areapportioned to the needs of the applicationflows that will be using the device.

The resources might also be controlled byIntServ policies created by networkmanagement.

RSVP is the only currently implemented

signaling protocol used for IntServ thatcommunicates with the QoS processesrunning on various nodes along the route.

QoS in MPLS


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Differentiated Services (Diff-Serv)

DiffServ is often compared to a set of buildingblocks that can be used in various ways toprioritize the packets in the QoS flow.

With the Diffserv model, network traffic isclassified by designated fields in the header andthen examined at each node for the predefinedtreatment it should receive.

The DiffServ effort was first focused on the TOSbyte definition for the IP header

QoS in MPLS DiffServ


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The fundamental DiffServ concept is that

each IP packet carries its CoS informationwithin the IP packet header. A set ofpacket with the same TOS field valueshould receive the same treatment.

Version Header lengthTOS8 bit

0 1 2 3 4 5 6 7

QoS in MPLS DiffServ

h S


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The DS Byte

The TOS field was later defined as Diffserv

Byte field

DS Byte field uses the former TOS fieldlocation in the IPv4 header.

The first six bits are used as an index valueto a table implemented in the network node.

This is called Diff-Serv code point (DSCP)field.

Thus the 6 bits give 64 independent values.

The DSCP index maps to various datatreatments that handle CoS. These datatreatments are called per-hop behaviors

QoS In MPLS Per Hop Behaviors


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A Per Hop Behavior PHB includes CoS handling

mechanism such as queue selection, scheduling

and congestion control. The currently defined

PHBs include

Expedited Forwarding (EF) Gold

Assured Forwarding (AF) Silver

Default Behavior (DB) Bronze

QoS In MPLS Per Hop Behaviors


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An EF is required when loss,jitter, and delay must

be low. This PHB generally prevents any queues

in the node from increasing in size

An AF PHB assures the delivery but does not

guarantees the delay, jitter and other QoS

parameters

A DB PHB is the default best effort behavior

MPLS VPN


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VP Ns based on MP LS provides the best of both

worlds as it has inherent self-healing ability by

automatically re-routing traffic and also ensures

quality of service including high throughput with

low latency and jitter.This is possible because

unlike the public internet, the routers are

interconnected over fully dedicated long distance

backbone transmission network of the service

provider.

MPLS VPN provides


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MP LS VPN provides low cost, highly secure and

highly reliable enterprise networking solution.

ERP solutions which are very popular among

enterprises, can easily run over the MP LS-VPNnetwork inter connecting the various branch offices,

dealers and factories with the main offices spread

all over the country.

MPLS VPN provides


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Upgrading the network with higher band width as

and when required.

MP LS VPN provides common infra structure for

carrying wide range of services like Multimedia

Services, Intra Office Voice Calls, VOIP, Video

Conferencing, Data Transfer, E -Mail, Access VP N,

Intranet, Extranet, Internet and Multicast etc.,

Benefits of MPLS VPN


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Reduces customers networks complexity and

cost. Need to provide only one connection fromtheir office router to service provider edgerouter.

Service provider manages the

interconnections. Layer 3 VPN service is also possible.

MPLS VPN network also provides Layer 2Service which is almost like the physical

leased line.

MP LS VP N network is capable of handlingencryption data.


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