Transcript will only work

MANETS
Justin Champion
Room C203, Beacon Building
Tel 3292,
[email protected]
Content

Introduction
 Why
consider this
 Types of Network
 Issues in transferring data

Conclusion
Why is this a consideration

So far in lectures we have looked at cellular
networks
 These
are infrastructure based
The access points to the network never move
 The contents within the network will always be in the
same point
 The nodes once issued with a IP address will always
be connected at the same point

 The
university uses a fixed infrastructure network
 The Internet is based on a known structure to
route information between points
Infrastructure Based Network
B
HS1 HS2 OK1 OK2 PS
HS1 HS2 OK1 OK2 PS
1 2 3 4 5 6 7 8 9101112
COLACTSTA-
CONSOLE
Router
A
1 2 3 4 5 6 7 8 9101112
COLACTSTA-
CONSOLE
Other Types of Networks

PicoNets
 These
are a small network of a number of nodes
communicate
 Good example is Bluetooth with 1 master and 7
slaves communicating

Scatternets
 A Scatternet
is several Piconets sharing one
common device

These are all examples of adhoc networks
 Commonly
know as MANETS
Scatternet
PicoNet
PicoNet
device
device
device
device
device
device
device
PicoNet
device
device
device
device
device
device
Why is this a consideration

With mobile networks the infrastructure can
change
 Consider
the previous diagram of a Scatternet
 If all devices are accessing the network through
an access point

This will be fixed as a point into the network

As long as the device is within range
 AdHoc
networking consists of when there is no
set infrastructure

These are referred to as MANET’s

Mobile Ad hoc Networks (MANETS)
MANETS – why ?

Why ?
 By
having common communication standards
Allows all of the devices to communicate with each
other
 Wireless standards will be covered in another week

 No
installation required
The parties communicating can get together to transfer
information
 No prior knowledge of each other is required
 No agreement or identification is needed to start the
communications

MANETS –Common use

Usage
 Business meeting
 All of the parties at the meeting can receive the presentations
being used
 Business details can be exchanged
 Game players
 Come together for the game to play
 Afterwards then move to another group and join that game
 Sensor networks
 Where a number of wireless nodes are distributed
 Emergency Service use
 Allows a network to set quickly until full infrastructure can be
arranged
MANETS – $100 laptop

Designed to allow educational computing
power in regions of the world that currently
can not have it



This should connect them to the Internet and allow
people access to resources we take for granted
http://www.laptop.org/
Using a single connection to get all devices
networking

Each device will talk to its neighbours


http://www.silicon.com/research/specialreports/opens
ource/0,3800004943,39156063,00.htm
Uruguay has purchased 100,000 of these 29th Oct 07
 http://news.bbc.co.uk/1/hi/technology/7068084.st
m
MANETS – Usage

LANDroid
http://www.darpa.mil/ipto/solicitations/open/07-46_PIP.pdf
 Generating
a MANET and adjusting itself to
ensure optimal communications
MANET Demo
 All

Devices are in range
All devices receive all communications
Sending from A to C is
straightforward as no packet
routing is required
Range
A
B
Hand held computer
Hand held computer
C
Hand held computer
MANET Demo
 A wants

to communicate with C
Packets can be sent through B
Range
Range
Range
Hand held computer
Hand held computer
Hand held computer
A
B
C
Difficulties

Difficulty comes from
 Routing

Finding a route through the network
 Battery

Life
Other users could be using your limited battery
capability
 Security

information
Concerns
The routing party could also be taking copies of any
data transferred
Routing in a MANET
Range
Hand held computer
Range
Range
B
Hand held computer
Hand held computer
C
A
No Route from A to C !
Routing in a MANET

The nature of mobile networks indicates that
nodes move
 This
means that a route to a particular point may
also change
 Special protocols are used to keep the routing
table current

AdHoc routing protocols which come in two varieties
Re-active
 Only finds a route as and when required
 Pro-Active
 These always search for the best or better routes

Routing in a MANET

Examples of adhoc routing protocols
 Complete

en.wikipedia.org/wiki/Ad_hoc_protocol_list
 Example

techniques
Pro-active


list of all techniques
Wireless Routing Protocol (WRP)
Re-active

Temporarily Ordered Routing Algorithm (TORA)
Routing using WRP

Wireless Routing Protocol (WRP)
 Is

a table driven method of communicating
Each of the nodes will have a table which contains all
routes in the network

 The
For WRP these are four tables, Routing, distance, route cost
and message retransmission
method is proactive so
The routes are worked out before they are needed
 They are constantly updated



Giving a overhead to the network and the battery of the device
Even routes which may never be needed are
calculated and stored
Routing using WRP

WRP operates by
 Each
node must send a “hello” message within a
certain time-frame

If receiving nodes do not know the “hello” message
node the routing table is updated of all receiving nodes
 Each
node will forward the list of known routes to
all other neighbour nodes
Neighbour nodes are the ones within range of
transmissions
 The list is sent out periodically
 Sent out immediately in the event of a change to the
network

Routing using TORA

Temporally Ordered Routing Algorithm (TORA)
 Routes
are only created as required
 Packets are sent out asking for the destination node
This packet is then forwarded to each neighbouring node
 Until the destination is found or a break is discovered

 This
method may produce multiple routes to a
single destination

This is potentially good for load sharing
Sensor Network

These are a number of nodes distributed within an area

The nodes can be any size



Small would be located in a building to detect fire
Large would be placed at location detecting ground movements
An example from Intel is used to monitor ship vibration


They need

A source of power




http://www.intel.com/research/exploratory/sensornetwork_operation.htm
Battery or mains
Processing and detecting capabilities
Wireless Communication to transfer the information
A good research paper on this subject

http://ieeexplore.ieee.org/iel5/7384/32301/01507522.pdf?isnumber=&arn
umber=1507522, 2005

This link will only work within the university network
Sensor Network

These are a number of nodes distributed within an area

Instead of a few detectors, this uses a large number of small
detectors
Fire Detectors in a
Building
Fire Alarm
Central
Detector
Sensor(s)
Security

Forwarding packets allows multiple nodes to
get access to the data
 Security
is required if the data is confidential
 Easiest method is the use of Internet Protocol
Security (IPSEC)
Although available for IPv4, it is now mandatory for the
use of IPv6
 Either the data within the packet can be encrypted or


The entire packet can be placed inside another packet
encrypting everything
Security

Without security of some kind
 How

Consider the fire example previously


would you know a message is genuine
What would stop someone from sending a spurious signal to
active the fire system
Ensure your data is confidential

A
Are you happy for node B to be able to read/store everything
you send?
B
Packet 1
Packet 2
Packet 3
C
Battery

Mobile devices by there nature are battery
powered
 This



gives a limited amount of power to the device
The biggest use of this power is the wireless networking
Using adhoc networking some of the parties will drain the
battery without any benefit! (node B in the example below)
Also throughput is limited, so if B wishes to communicate part
of the available network speed is being used

It is about fair sharing of resources, with each device benefiting
A
B
Battery Power
C
Conclusion

We have looked at
 Networking
models
PicoNets
 ScatterNets
 MANETS


Considerations