Adhoc networks

1. VINISH A LIK K A L
AS S IS TANT PRO FE S S O R
ME A E NG INE E RING CO LLE G E
Mobile Ad Hoc Networks
(MANET)

2. MANET
 A MANET is a type of ad hoc network that can change locations and
configure itself on the fly.
 Because MANETS are mobile, they use wireless connections to connect
to various networks. This can be a standard Wi-Fi connection, or
another medium, such as a cellular or satellite transmission.
 Example: TSP( Travelling Sales Man Problem)
https://www.youtube.com/watch?v=7B8Sx_nAxLk

3. Ad hoc & Infrastructure Networks
Ad hoc wireless network is a collection of
nodes (or routers ) mobile wireless that
dynamically existence without the use of
existing network infrastructure or
centralized administration
Devices on the network all
communicate through a single
Access point (AP: Access Point is
devices that allows the wireless
devices to connect to a wired
network using Wi -Fi

4. Infrastructure Network

5. Histrory

6. Ad hoc Networks

7. Mobile Ad hoc Networks

8. Overview
 Collection of digital data terminals equipped with wireless transceivers
that can communicate with one another without using any fixed
networking infrastructure.
 Communication is maintained by the transmission of data packets over
a common wireless channel. The absence of any fixed infrastructure,
such as an array of base stations, make ad hoc networks radically
different from other wireless LANs. Whereas communication from a
mobile terminal in an infrastructured network, such as a cellular
network, is always maintained with a fixed base station, a mobile
terminal (node) in an ad hoc network can communicate directly with
another node that is located within its radio transmission range
 In order to transmit to a node that is located outside its radio range,
data packets are relayed over a sequence of intermediate nodes using a
store-and-forward multi hop transmission principle. All nodes in an ad
hoc network are required to relay packets on behalf of other nodes

9. Manet: Mobile Ad-hoc Networking
Fixed
Network
Mobile
Devices
Mobile
Router
Manet
Mobile IP,
DHCP
Router End system

10. Properties of a MANET
 Seamless interaction and ubiquitous mobile computing environment
 Neighbor discovery─ One of the important characteristics of a MANET
node
 Data routing abilities ─ data can be routed from a source node to a
neighboring node
 Flexible network architecture and variable routing paths ─ to provide
communication in case of the limited wireless connectivity range and
resource constraints
 Flexibility─ enables fast establishment of networks
 When a new network is to be established, the only requirement is to
provide a new set of nodes with limited wireless communication range
 A node has limited capability, that is, it can connect only to the nodes
which are near by and thus consumes limited power

11. Properties of a MANET
 Peer-to-Peer connectivity
 Computations decentralization - independent computational, switching
(or routing), and communication capabilities
 Weak connectivity and remote server latency
 Unreliable links to base station or gateway ─ failure of an intermediate
node results in greater latency in communicating with the remote
server
 Resource constraints─ Limited bandwidth available between two
intermediate nodes
 Node may have limited power and thus computations need to be
energy-efficient
 No need of access-point

12. spectrum of MANET applications
 a)Content distribution & content synchronization:
 b) Multicast network:
 c) Mesh network:
 d) Image acquisition, processing and distribution using MANET:
 e) IPv6 integration and wireless sensor networks:

13. MANET applications
a)Content distribution & content synchronization:
Let us consider in an enterprise, there are a number of Bluetooth-
enabled mobile handheld devices, PCs, laptops, and Wi-Fi access
points, the MANET used for content distribution, by following PIM,
information dissemination, information fusion, and file sharing
techniques.
b) Multicast network:
 MANET supports multicasting by organizing the nodes in
multicast tree topology. Here we use CGSR protocol(Cluster-Head
Gateway Switch Routing) for multicasting.

14. MANET applications
c) Mesh network:
Mesh-based mobile networks offer highly dynamic autonomous topology
segments for the robust IP-compliant data services. The mesh is inexpensive to
infrastructure based cellular mobile networks.
 Mesh network is build by using PUMA (Protocol for unified multicasting
through announcements) protocol. Mesh connects MANET nodes each other.
 We know that the multicast tree is different from mesh. Multicast tree provides
a single path between the sender and receiver, but mesh supports multiple
paths between sender and receiver.
 But we know that the error rate is high on wireless links so PUMA can send
the packets from sender to receiver through various paths

15. MANET applications
d) Image acquisition, processing and distribution using MANET:
Let us consider number of imaging devices forming a MANET.
 low cost digital still camera with a wireless network interface, Wireless
Webcam, mobile device connected to a digital still camera, mobile
phones, and pocket PCs equipped with an image acquisition sensor.
 The following are some applications where MANETs to apply;
1.Remote view finder by security personal in office.
2.Remote processing on a computer for a video from wireless webcam or from
other devices.
3.Image file transfer
4. Messaging and data transmission to remote device using 802.11b.
5. Remote controlling.

16. MANET applications
e) IPv6 integration and wireless sensor networks:
 IPv6 is a new generation internet protocol used for internet radio and
real time video over the internet.
 Now we integrate IPv6 with MANET and wireless sensor networks.
This integration leads to pervasive computing and other innovative
applications.

17. Routing and various Routing algorithms
Routing
Routing refers to establishing the routes that data packets take on their way to
a particular destination.
Example of Ad Hoc Network

18. Routing
Asymmetric links:
Node A receives a signal from node B. But this does not tell us anything about
the quality of the connection in reverse. B might receive nothing, have a weak
link, or even have a better link than the reverse direction
Redundant links:
In ad-hoc networks nobody controls redundancy, so there might be many
redundant links up to the extreme of a completely meshed topology.
Interference:
In wired networks links exist only where a wire exists, and connections are
planned by network administrators. This is not the case for wireless ad-hoc
networks. Links come and go depending on transmission characteristics, one
transmission might interfere with another, and nodes might overhear the
transmissions of other nodes.

19. Routing
Dynamic topology:
In ad hoc networks, routing tables must somehow reflect these frequent changes
in topology, and routing algorithms have to be adapted. Routing algorithms
used in wired networks would either react much too slowly or generate too
many updates to reflect all changes in topology.

20. Routing Algorithms
“Routing algorithm is that part of the network layer software responsible for
deciding which output line an incoming packet should be transmitted on”
Routers has Two process inside it:
1)Forwarding:-
Each packet as it arrives, looking up the outgoing line to use of it in routing table
2)Other process is responsible for filling in and updating the routing table

21. Routing Algorithms
Certain properties are desirable in Routing Algorithms
 Correctness
 Simplicity
 Robustness
 Stability
 Fairness
 Efficiency
Routing Algorithms can be grouped in to two major classes
 Non Adaptive or Static Routing
 Adaptive Routing or Dynamic Routing

22. Non Adaptive or Static Routing
 Choice of route is computed in advance offline and downloaded to the routers
when the network is booted.
 Do not use the measurement of current conditions
 Static routes are downloaded at boot time
Routing decision not changed based on traffic

23. Adaptive Routing or Dynamic Routing
 Change their routing decisions to reflect changes in topology
 Change routes dynamically
Gather information at runtime
 Locally
 From adjacent routers
 From all other routers
Change routes
 When load changes
 When topology changes
Changes the routing decision based on traffic

24. Pros & Cons
Pros
 The purpose of adaptive routing is to help prevent packet delivery failure.
 It improve network performance
 It relive network congestions
Disadvantages
 Makes the node overloaded
 Less Secure
 More bandwidth

25. Traditional routing algorithm
In Wired network
1. Static
2. Dynamic
a) Distance Vector
b) Link State
Distance Vector (DV)
Each node maintains a table giving the distance from itself to all possible destination.
Periodically broadcasts update packets to each of the neighbors.
Bellman-Ford algorithm
Finding the shortest path to determine the correct next hop of its neighbors.
When presented a packet for forwarding to some destination, each router simply
forwards the packet to the correct next hop router.
Problem: route looping & count to infinity

26. Traditional Routing Algorithm

27. Advantages of Distance Vector routing –
 It is simpler to configure and maintain than link state routing.
Disadvantages of Distance Vector routing –
 It is slower to converge than link state.
 It is at risk from the count-to-infinity problem.
 It creates more traffic than link state since a hop count change must
be propagated to all routers and processed on each router. Hop count
updates take place on a periodic basis, even if there are no changes in
the network topology, so bandwidth-wasting broadcasts still occur.
 For larger networks, distance vector routing results in larger routing
tables than link state since each router must know about all other
routers. This can also lead to congestion on WAN links

28. Routing
Link State (LS)
Each node maintains a view of the network topology with a cost for each link.
Each node periodically broadcasts the cost of its outing links to all other nodes.
Using a shortest-path algorithm to choose its next hop for each destination.

29. Routing

30. Problems with Routing
Is it possible to use standard routing protocols?
● Distance-vector protocols
● Slow convergence due to “Count to Infinity” Problem
● Creates loops during node failure, network partition or congestion
● Link state protocols
● Use flooding technique and create excessive traffic and control overhead
● Require a lot of processor power and therefore high power consumption

31. Problems with Routing
 Limitations of the Wireless Network
● packet loss due to transmission errors
● variable capacity links
● frequent disconnections/partitions
● limited communication bandwidth
● Broadcast nature of the communications
 Limitations Imposed by Mobility
● dynamically changing topologies/routes
● lack of mobility awareness by system/applications
 Limitations of the Mobile Computer
● short battery lifetime
● limited capacities

32. Goal of Routing Protocol
1. Minimal control overhead:
Control messaging consumes bandwidth, processing resources and battery
power to both transmit and receive a message.
Should not send more than the minimum no of control message they need for
operation.
While transmitting is roughly twice as power consuming as receiving. Thus
need to reduce control messaging
2. Minimal processing overhead
Algo that are computationally complex require more processing cycles, thus
consume more resources.
Protocol should be lightweight and use a minimum of processing resources
from the mobile devices

33. Goal of Routing Protocol
3. Multihop routing capability
Transmission range of mobile node is limited.
Routing protocol must be able to discover Multihop routes between
source and destination so that communication between those node is
possible who are not in direct transmission range of each other.
4. Dynamic topology maintenance
Once route is established , link may be break due to movement of
nodes.
A viable routing path must be maintained even while the intermediate
nodes, or even the source or destination nodes are moving.
If link breaks, it must be handled quickly with a minimum of 15
associated overhead.

34. Goal of Routing Protocol
5. Loop prevention
When a routing loop exits , data and control packets may traverse the
path multiple times until either the path or fixed and the loop is
eliminated or until he time to live (TTL) of the packet reaches zero.
As bandwidth is scarce and packet processing and forwarding is
expensive, routing loops are extremely wasteful of resources.
Loops should be avoided all the times

35. Routing Protocol : Assumptions
1. All nodes are homogenous resources and capabilities.
2. Same transmission range of nodes.
3. Bi-directional links
4. Protocol are designed for moderately sized networks of 10 to 100 nodes.

36. Routing Protocol
Routing protocols category :
(a) Table-driven
(b) Source-initiated on-demand-driven..

37. Table Driven / Proactive protocols
 Traditional distributed shortest-path protocols
 Maintain routes between every host pair at all times
 Based on periodic updates; High routing overhead
 Example: DSDV (destination sequenced distance vector)
On-Demand Driven/ Reactive protocols
 Determine route if and only when needed
 Source initiates route discovery
 Example: DSR (dynamic source routing)
Hybrid protocols
 Adaptive; Combination of proactive and reactive
 Example : ZRP (zone routing protocol)

38. Table Driven / Proactive protocols
 Proactive protocols are based on periodic exchange of control messages and
maintaining routing tables.
 Derived from traditional distance vector and link state protocol used in
wireline internet.
 Each node maintains complete information about the network topology locally.
 This information is collected through proactive exchange of partial routing
tables stored at each node. Since each node knows the complete topology, a
node can immediately find the best route to a destination.
Limitation :
 Generates large volume of control messages and this may take up a large part
of the available bandwidth.
 The control messages may consume almost the entire bandwidth with a large
number of nodes and increased mobility.

39. Table Driven / Proactive protocols
Maintains fresh lists of destinations & their routes by periodically distributing
routing tables throughout the network
Attempts to maintain consistent, up-to-date routing information from each
node to every other node in the network.
Require each node to maintain one or more tables to store routing information.
They respond to changes in network topology by propagating route updates
throughout the network to maintain a consistent network view.
These Protocols are differ in the number of necessary routing-related tables
and the methods require to broadcast the changes in network structure.
Some examples of proactive protocols are :
Destination Sequenced Distance Vector (DSDV)
WRP (Wireless Routing Protocol)
CGSR (Cluster Switch Gateway Protocol)

40. Destination Sequenced Distance Vector (DSDV)
 Table-driven routing protocol
 Expansion of distance vector based on Classical distributed Bellman-Ford
routing mechanism include freedom from loops in routing tables.
 Main Advantage of using this protocol is that it avoid the routing loops in a
mobile network of routers.
 Each node maintains a routing table of the possible destinations within the no
partitioned network and the number of routing hops / radio hops (Hand Over
Point) to each destination are recorded.
 Routing information is always made readily available, regardless of whether
the source node requires a route or not.

41.  A sequence numbering system is used to allow mobile hosts to distinguish
stale routes from new ones.
 Routing table updates are sent periodically throughout the network to maintain
table consistency.
 It generates a lot of control traffic in the network, rendering an inefficient
utilization of network resources.
 To minimize the routing updates, variable sized update packets are used
depending on the number of topological changes.
DSDV uses two types of route update packets.
 Full Dump update Packet
 Incremental update Packet

42. Security in Mobile Ad-hoc Networks:
security is important for maintaining privacy in mobile ad-hoc
networks, the following are some of the security problems in wireless
computing systems;
 Confidentiality:
 Integrity:
 Pre-Keying:
 Availability:
 Non-Repudiation:
 Resource constraint:
 Power of detection:
 Interception:
 Replay:
 Stealing of subscriber service:

43. Security in Mobile Ad-hoc Networks:
 Mobility risks:
 Spoofing:
 Reconfiguration:
 eavesdropping:
 Traffic analysis:

44. Security in Mobile Ad-hoc Networks:
Confidentiality:
Only intended user only able to read the data. Encryption of the data
before the transmission and decryption at the user end is employed for
confidentiality.
Integrity:
Here data integrity as well as the system integrity to be maintained to
avoid manipulated messages and messages to wrong nodes
Pre-Keying:
A key should be exchanged before the transmission of the data between
the sender and receiver for decryption of the data at receiver side. The
key exchanging is through wireless link, it increases the risk of key
tapping

45. Security in Mobile Ad-hoc Networks:
Availability:
There may be a denial of service attack, a source may block the availability of
data at the user end due to intermediate router misdirection.
Non-Repudiation:
A sender is unable to refuse send a message or information.
Resource constraint:
Resource constraint of mobile systems have several points;
a) The service provider (server) runs slower than a node.
b) Less memory availability.
c) Limited battery life.
d) Certain kinds of attacks.

46. Security in Mobile Ad-hoc Networks:
Power of detection:
A mobile device may not detect the signals therefore unable to get the data by
jamming the signals
Interception:
Some times the signals may intercepted.
Replay:
Some time the attacker replay the same sequence of messages to the server by
hacking the authentication requests.
Stealing of subscriber service:
Hijacking of user name and password by an attacker, results getting service of
another client.
Mobility risks:
Frequent change in locations may lead to changing of routing path frequently.

47. Security in Mobile Ad-hoc Networks:
Spoofing:
A node can imitate the address of another node in ad-hoc network. Suppose
spoofing at common node leads to chocking of all routes.
Reconfiguration:
Changing of network parameters due to configuration attacks may cause
configure the network in frequent intervals of time
eavesdropping:
Certain times unsolicited messages from third party during a talk between two
nodes.
Traffic analysis:
By extracting the network traffic analysis some security problems may occur.