Remo Cocco, Malik Ahmed, Dan Urbano, and Vasil Hnatyshin Department of Computer Science Rowan University

Remo Cocco, Malik Ahmed, Dan Urbano, and Vasil HnatyshinDepartment of Computer ScienceRowan University

AODV ROUTING

Topics

Routing – An Overview Forwarding Table

Mobile Networks Some Semantics Reactive vs Proactive

AODV Routing Routing Table RREQ and RREP

Location-Aided Routing

But first…

We would like to congratulate Dr. VH He will be honored in the Ki Delta’s Pi

International Honor Society 100th anniversary book

It features stories about teachers who have inspired students

The story will be read on March 8th at KDP’s Founder’s Day celebration

Topics





Routing – An Overview

What’s the problem? The Source Node (S) wants to send

information to the Destination Node (D). Where does S send its packets of information

to in order for the packets to end up at D?

R2

S

R4

R3

R1

D

Routing – An Overview

Solution – Keep a forwarding table Source Node S keeps information about where

to send the packets to so that they end up at Destination D.

Node S looks up this information inside its forwarding table when it is about to send out packets.

R2

S

R4

R3

R1

D

Topics





Routing – Forwarding Table

A Simplified Version of a Forwarding Table Each entry has the following fields:

Destination IP Address Destination Sequence Number Next Hop

Destination IP Address

Destination Sequence #

Next Hop

209.85.148.105 123456 150.250.190.1150.250.1.1 178965 150.250.190.1

209.191.122.70 224870 150.250.190.1



Next Hop

209.85.148.105 123456 150.250.190.1150.250.1.1 178965 150.250.190.1

209.191.122.70 224870 150.250.190.1



Next Hop

209.85.148.105 123456 150.250.190.1150.250.1.1 178965 150.250.190.1

209.191.122.70 224870 150.250.190.1



Next Hop

209.85.148.105 123456 150.250.190.1150.250.1.1 178965 150.250.190.1

209.191.122.70 224870 150.250.190.1

R2

S

R4

R3

R1

D


S refers to D by its IP address. D’s IP address = 150.250.1.1

The following entry tells S who to send the next packet to.



Next Hop

209.85.148.105 123456 150.250.190.1150.250.1.1 178965 150.250.190.1

209.191.122.70 224870 150.250.190.1



Next Hop

209.85.148.105 123456 150.250.190.1150.250.1.1 178965 150.250.190.1

209.191.122.70 224870 150.250.190.1


Here’s Another Problem: How does the information get in the

forwarding table to begin with?

The Solution Routing protocols will find routes from a source

to a destination. These protocols will fill in the information in

the forwarding table.

Topics





Mobile Networks

The mobile networks we will be teaching today are known as MANETs

Mobile Ad-hoc NETworks Mobile – the nodes of the network can move Ad-hoc – does not rely on existing infrastructure Network – a collection of computers (nodes) connected

by communication channels Example: disaster relief – the infrastructure was

wiped out but the need for communication exists Since devices are mobile and can move freely,

each device must be able to find new routes itself.

Topics





Mobile Networks – Some Semantics Node

A computer which must route all messages wirelessly through other nodes

Nodes can move around You can think of nodes as laptops or cell phones that

can not use a radio tower to get a signal Neighboring Nodes

Any two nodes which can directly communicate with each other

Unicast, Multicast, Broadcast Visualizations of each of these are on the following

slides. Flooding

A large number of packets flow through the network that can cause congestion

Packet

For Node

X

Mobile Networks – Some Semantics Unicast

Delivers a message to a single specified node. Here is an example of sending a unicast

message:

Packet

For Node

X

Packet

For Node

X

Packet

For Node

X

Packet

For Node

X

Packet

For Node

X

Packet

For Node

X

Packet For

Nodes X,Y,Z,

T

Mobile Networks – Some Semantics Multicast

Delivers a message to a group of nodes that expressed interest in receiving the message.

Here is an example of flooding a multicast message:

Packet For

Nodes X,Y,Z,

T

Packet For

Nodes X,Y,Z,

T

Packet For

Nodes X,Y,Z,

T

Packet For

Nodes X,Y,Z,

T

Packet For

Nodes X,Y,Z,

T

Packet For

Nodes X,Y,Z,

T

Packet For

Nodes X,Y,Z,

T

Packet For

Nodes X,Y,Z,

T Packet For

Nodes X,Y,Z,

T

Packet For

Nodes X,Y,Z,

T

Packet For

Nodes X,Y,Z,

T

Packet

For All Nodes

Mobile Networks – Some Semantics Broadcast

Delivers a message to all of the nodes in the network.

Here is an example of flooding a broadcast message:

Packet

For All Nodes

Packet

For All Nodes

Packet

For All Nodes

Packet

For All Nodes

Packet

For All Nodes

Packet

For All Nodes

Packet

For All Nodes

Packet

For All Nodes

Packet

For All Nodes

Packet

For All Nodes

Packet

For All Nodes

Topics





Mobile Networks:Reactive Vs Proactive

Routing protocols are needed to find routes between a source node and a destination node

Reactive – “I need to send information to another node but I don’t have a route yet! I will find one.”

Proactive – “I just entered a network. Before I even begin to send information, I’m going to find a route to every other node in the network just to be prepared ahead of time.”

Mobile Networks:Reactive Vs Proactive

Reactive Only calculate new routes

when they are needed Do not maintain routes to

every node in the network Also known as On

Demand Routing Efficient for low mobility,

light traffic networks. Examples

DSR AODV

Proactive Try to calculate all of the

routes beforehand Actively maintain updated

routes to every node in the network

Also known as Table Driven Routing

Incurs overhead when the network changes

Examples: IS-IS OSPF

Topics





AODV Routing

d – Hoc Does not rely on pre-existing infrastructure

n – Demand A reactive protocol – only create routes on

demand

istance

ector

A

O

D

V

Vector Distance Vectors are used to calculate routes from

one mobile node to the next since routers are not usedin an ad-hoc protocol

AODV Routing

Designed for mobile networks holding hundreds of nodes where all nodes trust each other.

Used to find a route from a source node to a destination node when no current path is known.

Does this problem sound familiar?

AODV Routing

The Problem From Before: How does the information describing the route

from source node to destination get into the forwarding table to begin with?

The Solution From Before: Routing protocols will find routes from a source

to a destination and will fill in the information in the forwarding table.

This is the job of AODV!

AODV Routing

The basic idea when source S has a route to destination D The forwarding table at S declares to who send

the packets to in order to eventually reach D. A unicast message is sent from S to that

intermediate node. Lots of uninterested nodes will receive the

message but only the particular intermediate node it was designated for will continue to send the packets along to other nodes in the same manner until the packets reach D

AODV Routing

The basic idea when source S does not have a route to destination D S sends out a multicast control packet called

RREQ, or “route request” to all neighboring nodes. Each neighbor checks to see if it is actually the

destination or if it has a route to the destination. If not, send out another RREQ to their own neighbors. This

is called flooding. If any node receives an RREQ and is the

destination or has a route to it, send back a unicast RREP, or “route reply” control packet to the node that sent the RREQ.

AODV Routing

Route Discovery Process via flooding .

RREQ for

Node D

RREQ for

Node D

RREQ for

Node D

RREQ for

Node D

RREQ for

Node D

RREQ for

Node D

RREQ for

Node D

RREQ for

Node D

RREQ for

Node D

RREQ for

Node D

RREQ for

Node D

RREQ for

Node D

RREP for

Node S

RREP for

Node S

RREP for

Node S

AODV Routing

The New Route

Topics





Routing Table

A Simplified Version of a RoutingTable Each entry has the following fields:

Destination IP Address Destination Sequence Number Network Interface Next Hop Hop Count Lifetime



Network Interface

Next Hop Hop Count Lifetime

209.85.148.105 123456 eth0 150.250.1.1 14 126150.250.190.204 178965 eth0 150.250.190.1 3 2544209.191.122.70 224870 wlan0 150.250.1.1 12 1021



Network Interface


209.85.148.105 123456 eth0 150.250.1.1 14 126150.250.190.204 178965 eth0 150.250.190.1 3 2544209.191.122.70 224870 wlan0 150.250.1.1 12 1021



Network Interface


209.85.148.105 123456 eth0 150.250.1.1 14 126150.250.190.204 178965 eth0 150.250.190.1 3 2544209.191.122.70 224870 wlan0 150.250.1.1 12 1021



Network Interface


209.85.148.105 123456 eth0 150.250.1.1 14 126150.250.190.204 178965 eth0 150.250.190.1 3 2544209.191.122.70 224870 wlan0 150.250.1.1 12 1021



Network Interface


209.85.148.105 123456 eth0 150.250.1.1 14 126150.250.190.204 178965 eth0 150.250.190.1 3 2544209.191.122.70 224870 wlan0 150.250.1.1 12 1021



Network Interface


209.85.148.105 123456 eth0 150.250.1.1 14 126150.250.190.204 178965 eth0 150.250.190.1 3 2544209.191.122.70 224870 wlan0 150.250.1.1 12 1021



Network Interface


209.85.148.105 123456 eth0 150.250.1.1 14 126150.250.190.204 178965 eth0 150.250.190.1 3 2544209.191.122.70 224870 wlan0 150.250.1.1 12 1021

Topics





RREQ – Route Request

An RREQ is made up of the following fields:


Hop Count ID Number Destination IP Address


Originator IP Address

Originator Sequence #

1 12345 209.191.122.70 55 150.250.190.204 126

Each node asks, “Do I have a path to destination?” “No.” Increment hop count and re-

broadcast.Hop Count ID Number Destination IP

AddressDestination Sequence #



1 12345 209.191.122.70 55 150.250.190.204 126





2 12345 209.191.122.70 55 150.250.190.204 126

Any nodes that have seen this RREQ before ignore it.





3 12345 209.191.122.70 55 150.250.190.204 126

“Oh, wait, I am the destination!”


Each node can use the IP Datagram that was wrapped around the RREQ packet. Each node can pull the IP address of the last

node that sent the RREQ. Each node now knows that in order to send a

reply back to Source S, the next hop must be that guy and it knows the hop count too from the RREQ packet.

D now knows who to send to in order to reach S.

D now sends a unicast RREP back to that guy, with intentions of reaching S to let S know everything’s OK

RREP – Route Reply

An RREP is made up of the following fields:


The Destination now sends a reply back to the source.

The Source has successfully received the RREP packet. Information from the packet can be used in the source’s routing table, such as ‘3 hops to reach D’ and the ‘next hop to reach D’ which it can pull from

the IP Datagram of the RREP it just received.

Topics





Location Aided Routing (LAR) AODV creates unnecessary overhead

when RREQ packets flood the entire network.

LAR aims to reduce this overhead by only allowing packets to propagate towards the destination.

LAR can use Global Positioning System (GPS) to determine the direction to send packets.

Location Aided Routing (LAR) Knowledge of each node’s physical location at

some previous point in time will help send packets in the right direction.

LAR does NOT use directional antennae. Instead, upon receiving an RREQ with

additional positional information, each node will determine if it is “in the right direction” of the destination.

If so, the node will re-broadcast the packet. If not, the node will ignore it, saving on

overhead.

Location Aided Routing (LAR) LAR Scheme 1

Knowing the average velocity (v) at which the destination is moving, we can draw a circle around the last known destination’s coordinates with radius v.

The destination is likely to bein this circle.

We will box this circle as sown: Only nodes inside this box

will continue to broadcastthe packet.

Location Aided Routing (LAR)

Location Aided Routing (LAR) LAR Scheme 2

LAR Scheme 2 does not rely on velocities of nodes.

The source can send out the destination’s last known coordinates in the RREQ packet along with its own.

Any node that receives the RREQand is closer to the destinationthen the last sender of the RREQshould re-broadcast the RREQwith its own coordinates attached.

Location Aided Routing (LAR)

Geo AODV

Our research was to improve on an idea for a better LAR algorithm.

A better algorithm will cause less overhead in an AODV network.

Former Rowan students, working with Dr. VH, developed an algorithm, Geo AODV.

We analyzed the algorithm and put it to the test against other LAR algorithms.

Geo AODV

Geo AODV defines an initial “flooding angle” from the source aimed towards the destination.

The cone-shaped figure might make for a more accurate bounds to the actual path from S to D then a rectangle.

Any node inside the conewill rebroadcast the RREQ.

Any node outside willignore it.

Implementation

We used OPNET 16.0 to implement the different routing protocols in order to observe the results.

Testing

The whole point of Location Aided Routing is to reduce the number of messages being broadcast. This cuts down on overhead This allows the network to process more

requests in a shorter period of time

We tested 2 schemes against regular AODV and looked at the number of RREQs being generated

Results

References

http://ntrg.cs.tcd.ie/undergrad/4ba2.05/group11/index.html

http://wiki.uni.lu/secan-lab/Reactive+Routing.html http://wiki.uni.lu/secan-lab/Proactive+Routing.html



http://wiki.uni.lu/secan-lab/Reactive+Routing.html

http://wiki.uni.lu/secan-lab/Proactive+Routing.html

Documents

Remo Cocco, Malik Ahmed, Dan Urbano, and Vasil Hnatyshin Department of Computer Science Rowan University