The document discusses Mobile IP and routing protocols for mobile networks. It begins with an overview of Mobile IP components including the mobile node, home agent, foreign agent, and correspondent node. It then describes how Mobile IP works using agent discovery, registration, and tunneling. It also discusses routing approaches for mobile ad hoc networks (MANETs) including proactive protocols like DSDV and reactive protocols like DSR and AODV. Link state and distance vector routing protocols are also summarized.
2. UNIT III
MOBILE NETWORKS LAYER
Mobiel IP – DHCP -Ad-Hoc –Proactive Protocal –DSDV -, Reactive
Routing Protocals – DSR, AODV, Hybrid Routing –ZRP, Multicast
Routing- Vehicular Ad Hoc networks ( VANET) – MANET Vs VANET –
Security
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3. WIRELESS NETWORKS
Need: Access computing and communication services, on the move
Infrastructure-based Networks
traditional cellular systems (base station infrastructure)
Wireless LANs
Infrared (IrDA) or radio links (Wavelan)
very flexible within the reception area; ad-hoc networks possible
low bandwidth compared to wired networks (1-10 Mbit/s)
Ad hoc Networks
useful when infrastructure not available, impractical, or expensive
military applications, rescue, home networking
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4. MOBILE IP
Mobile IP enables an IP node to retain the same IP address and maintain existing communications
while traveling from one link to another.
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6. MOBILE IP COMPONENTS
Mobile node (MN)
Home agent (HA)
Foreign agent (FA)
Correspondent Node (CN)
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7. MOBILE NODE (MN)
The Mobile Node is a device such as
-a cell phone,
-personal digital assistant,
-or laptop
whose software enables network roaming capabilities.
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8. HOME AGENT (HA)
Home Agent is a router on the home network serving as the anchor point for communication with
the Mobile Node;
it tunnels packets from a device on the Internet, called a Correspondent Node, to the roaming
Mobile Node.
(A tunnel is established between the Home Agent and a reachable point for the Mobile Node in the
foreign network.)
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9. FOREIGN AGENT (FA)
The Foreign Agent is a router that may function as the point of attachment for the
Mobile Node when it roams to a foreign network, delivering packets from the Home
Agent to the Mobile Node.
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10. CORRESPONDENT NODE (CN)
End host to which MN is corresponding (eg. a web server)
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11. HOW MOBILE IP WORKS
The Mobile IP process has three main phases
the following sections.
Agent Discovery
A Mobile Node discovers its Foreign and Home Agents during agent discovery.
Registration
The Mobile Node registers its current location with the Foreign Agent and Home
Agent during registration.
Tunneling
A reciprocal tunnel is set up by the Home Agent to the care-of address (current
location of the Mobile Node on the foreign network) to route packets to the Mobile
Node as it roams.
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12. TWO IP ADDRESSES FOR MOBILE NODE
Home address: static
Care-of address: topologically significant address
The care-of address is the termination point of the tunnel toward the Mobile Node
when it is on a foreign network. The Home Agent maintains an association
between the home IP address of the Mobile Node and its care-of address, which is
the current location of the Mobile Node on the foreign or visited network
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13. FEATURES OF MOBILE IP
Transparency : IP address should not be any effect of mobility on any ongoing
communication
Compatibility: It should compatible with existing Internet protocols.
Security: It should provide users with secure communication over internet.
Efficiency : It should neither result in large number of message nor should it incur too
much computational overheads
Scalability: It should also be scalable to support billions of moving hosts worldwide.
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14. KEY MECHANISM IN MOBILE IP
Three basic mechanisms
1. Discovering the care-of address
2. Registering the care-of address
3. Tunneling to the care-of address
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1.Discovery the care-of-address
Extension of ICMP Router Advertisement
• Home agents and foreign agents broadcast agent advertisements at
regular intervals
Allows for the detection of mobility agents
Lists one or more available care-of addresses
Informs the mobile node about special features
Mobile node selects its care-of address
Mobile node checks whether the agent is a home agent or foreign
agent
– Mobile node issues an ICMP router solicitation message
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Mobile IP Agent Advertisement Message
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2. Registration
Once a mobile node has a care-of address, its home agent must find out about it
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3. Tunneling to the care-of address
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20. MOBILE IP TUNNELING
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Across Internet
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21. Tunneling takes place to forward an IP datagram from home agent to a care-of-address.
When a home agent receives a packet addressed to a mobile host , it forwards the
packet to the care-of-address using IP-within-IP(encapsulation)
Using IP-within-IP, the home agent inserts a new IP header in front of the IP header of
any datagram.
Destination address is set to the home agent’s address.
Source address is set to the home agents address.
After stripping out the first header, IP processes the packet again.
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23. ROUTE OPTIMIZATION
All the data packets to the mobile node go through the home agent.
There will be a heavy traffic between HA and CN causing latency to increase.
To overcome this problem the following route optimization needs
• Enable direct notification of the corresponding host
• Direct tunneling from the corresponding host to the mobile host.
• Binding cache maintained at the corresponding host
The association of the home address with care-of-address is called binding
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24. CELLULAR WIRELESS
Single hop wireless connectivity to the wired world
Space divided into cells
A base station is responsible to communicate with hosts in its cell
Mobile hosts can change cells while communicating
Hand-off occurs when a mobile host starts communicating via a new base
station
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25. MULTI-HOP WIRELESS
May need to traverse multiple links to reach destination
Mobility causes route changes
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26. MOBILE AD HOC NETWORKS (MANET)
Host movement frequent
Topology change frequent
No cellular infrastructure. Multi-hop wireless links.
Data must be routed via intermediate nodes.
A
B A
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27. WHY AD HOC NETWORKS ?
Setting up of fixed access points and backbone infrastructure is not always viable
Infrastructure may not be present in a disaster area or war zone
Infrastructure may not be practical for short-range radios; Bluetooth (range ~ 10m)
Ad hoc networks:
Do not need backbone infrastructure support
Are easy to deploy
Useful when infrastructure is absent, destroyed or impractical
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28. MANY APPLICATIONS
Personal area networking
cell phone, laptop, ear phone, wrist watch
Military environments
soldiers, tanks, planes
Civilian environments
taxi cab network
meeting rooms
sports stadiums
boats, small aircraft
Emergency operations
search-and-rescue
policing and fire fighting
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29. AD-HOC BASIC CONCEPTS
A mobile ad hoc network (MANET) is a continuously self-configuring, infrastructure-less
network of mobile devices connected without wires
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30. CHARACTERISTICS
I. Lack of fixed infrastructure
II. Dynamic topologies
III. Bandwidth constrained, variable capacity links
IV. Energy constrained operation
V. Increased vulnerability
VI. Other characteristics
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31. APPLICATIONS
Communication among portable computers
Environmental monitoring
Military
Emergency applications
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32. MANET DESIGN ISSUES
Network size and node density
Connectivity
Network topology
User traffic
Operational environment
Energy constraint
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33. ROUTING
The purpose of routing is to find the best path between the source and the destination
for forwarding packets in any store and forward network.
Packet routing is usually a much more complex task in an ad-hoc compared to
infrastructure based networks.
The main complications arise on account of continual topology changes and limited
battery power of the nodes.
The destination node is not in transmission range of the source node, the route has to
be formed with the help of the intervening nodes in the network.
In MANET, the node making up a route may themselves move or shut down due to low
battery energy - therefore necessary to find a new route each time anode needs to
transmits a message, making routing an expensive and difficult task.
Based on the above discussion,
• Traditional routing protocols would not suitable in an ad hoc network.
• Each node in an ad hoc network needs to have routing capability and also needs to
participate in routing to keep the network operational.
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34. ESSENTIAL OF TRADITIONAL ROUTING PROTOCOL
The two important classes of routing protocols for traditional networks are the link
state and the distance vector
Both are extremely popular in packet-switched networks.
The shortest path is computed according to some specific cost metric such as the no of
hops in the route.
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35. APPROACHES TO SHORTEST PATH ROUTING
1. Link State Routing or Link State Protocol (LSP)
Each node knows the distance to its neighbors
The distance information (=link state) is broadcast to all nodes in the network
Each node calculates the routing tables independently
2. Distance Vector Routing
Each node knows the distance (=cost) to its directly connected neighbors
A node sends a list to its neighbors with the current distances to all nodes
If all nodes update their distances, the routing tables eventually converge
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36. LINK STATE ROUTING
Each node must
discover its neighbors
measure the delay (=cost) to its neighbors
broadcast a packet with this information to all other nodes
compute the shortest paths to every other router
The broadcast can be accomplished by flooding
The shortest paths can be computer with Dijkstra’s algorithm
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37. LINK STATE ROUTING: BASIC PRINCIPLES
1. Each router establishes a relationship (“adjacency”) with its neighbors
2.Each router generates link state advertisements (LSAs) which are distributed to all routers. The
LSA contains
The identity of the router originating the message
The identities of all neighbors.
LSA = (link id, state of the link, cost, neighbors of the link)
3. Each router maintains a database of all received LSAs (topological database or link state
database), which describes the network has a graph with weighted edges
4. Each router uses its link state database to run a shortest path algorithm (Dijikstra’s algorithm)
to produce the shortest path to each network
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38. A ROUTER IS CONNECTED TO OTHER ROUTERS THROUGH
LINKS
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39. LINK STATE ROUTING: PROPERTIES
Each node requires complete topology information.
Link state information must be flooded to all nodes.
All routers which are connected to the router added to the tree or in the
candidate list.
The delay in the candidate list to every other router in the tree are
compared
The shortest delay is moved in to the tree and attached to appropriate
neighbor router and removed from the candidate list.
The above steps are repeated till there are no more routers left in the
candidate list.
The network topology has been determined in the form of a shortest path
tree a router forms its routing table and uses it to find the best route to
any destination.
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40. OPERATION OF A LINK STATE ROUTING PROTOCOL
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Received
LSAs
IP Routing
Table
Dijkstra’s
Algorithm
Link State
Database
LSAs are flooded
to other interfaces
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41. ADVANTAGES AND DISADVANTAGES
Advantages
• Builds a topological map –Full knowledge of the network
• Fast convergence –Floods LSPs immediately
• Event-driven updates –LSP sent when there is a change, only contains information
regarding the affected link
• Hierarchical design –Areas can be used to separate routing traffic
Disadvantages
• Significant demands on memory and
• processing resources
• Requires very strict network design
• Requires a knowledgeable network administrator
• Initial flooding can impede network performance 41
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43. DISTANCE VECTOR
• The term vector means that routes are advertised as vector (distance, direction)Each
node maintains two tables:
• Distance is the number of hops between the two nodes and direction is defined in
terms of the next hop router to which the packets need to be forwarded.
• The distance vector protocols are based on well known Bellman-Ford algorithm.
• The protocol share everything in the network with neighbors by broadcasting the entire
router table
• Router updates its own routing table by examining the received information and in
turn informs its own neighbors of the changes, called ‘routing by rumor’
• The router do not have knowledge of the entire path, just know the following vector
Direction in which a packet should be forwarded.
Its own distance form the destination.
The two popular DV routing protocol are RIP(Routing Information Protocol) and
IGRP(Interior Gateway Routing Protocol)
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45. ROUTING IN MANET VS - TRADITIONAL NETWORKS
The three important ways in which a MANET routing protocol differs from
routing of packets in traditional networks.
In MANET each node act as a router, whereas ordinary nodes in a
traditional wired network do not participate in routing the packets.
In MANET the topology is dynamic because of the mobility of the routing,
the routing table become obsolete and routing process complicated.
In the simple IP based addressing scheme deployed in wired networks,
the IP address encapsulated in the subnet structures does not work
because of node mobility
To cope with the above three impermanent differences, MANET need to
carryout route discovery and route maintenance.
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46. TYPES OF COMMUNICATIONS
The node initiate the following types of communication.
Unicast: The message is sent to a single destination node.
Multicast: The message is sent to a selected subset of the network nodes.
Broadcast: The message is sent to all node in the network. Since unrestrained
broadcast can choke a MANET, applications usually do not use broad cast.
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47. A CLASSIFICATION OF UNICAST ROUTING PROTOCOLS
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48. UNICAST ROUTING PROTOCOLS
Many protocols have been proposed
Some specifically invented for MANET
Others adapted from protocols for wired networks
No single protocol works well in all environments
some attempts made to develop adaptive/hybrid protocols
Standardization efforts in IETF
MANET, Mobile IP working groups
http://www.ietf.org
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49. POPULAR MANET ROUTING PROTOCOLS
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50. ROUTING PROTOCOLS
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)
Reactive protocols
Determine route if and when needed
Source initiates route discovery
Example: DSR (dynamic source routing)
Hybrid protocols
Adaptive; Combination of proactive and reactive
Example : ZRP (zone routing protocol)
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51. PROTOCOL TRADE-OFFS
Proactive protocols
Always maintain routes
Little or no delay for route determination
Consume bandwidth to keep routes up-to-date
Maintain routes which may never be used
Reactive protocols
Lower overhead since routes are determined on demand
Significant delay in route determination
Employ flooding (global search)
Control traffic may be bursty
Which approach achieves a better trade-off depends on the traffic and mobility
patterns
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52. POPULAR MANET ROUTING PROTOCOL
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53. DESTINATION-SEQUENCED DISTANCE-VECTOR (DSDV) ROUTING PROTOCOL
DSDV is based on the table driven (Proactive) approach to packet routing, it extends
the distance vector protocol of wired networks (Bellman-Foard routing algorithm) .
Improvement made is the avoidance of routing loops through the use of number
sequencing scheme
Important steps in the operation of DSDV
1. Each node maintains information regarding routes to all the known destinations.
The routing information updated periodically.
2. This can be considered shortcoming – traffic overhead and maintain routes which
they may not use.
Full Update or full dump: Send all routing information from own table.
Incremental Update: Send only entries that has changed. (Make it fit into one
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54. Important steps in the operation of DSDV …..
3. Each router ic node in the network collects route information from all its
neighbors.
4. After gathering information, the node determines the shortest path to the
destination based on the gathered information.
5. Based on the gathered information, a new routing, table is generated
6. The router broadcast this table to its neighbors. On receipt by neighbors, the
neighbor nodes re compute their respective routing tables.
7. This process continues till the routing information become stable.
8. DSDV incorporates a sequenced numbering scheme .
9. Each routing advertisement comes with a sequence number
10. Advertise to each neighbor own routing information
Destination Address
Metric = Number of Hops to Destination
Destination Sequence Number
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11. Advertise to each neighbor own routing information
Destination Address
Metric = Number of Hops to Destination
Destination Sequence Number
12. Rules to set sequence number information
On each advertisement increase own destination sequence number (use only even numbers)
If a node is no more reachable (timeout) increase sequence number of this node by 1 (odd
sequence number) and set metric =
13. Update information is compared to own routing table
Select route with higher destination sequence number (This ensure to use always newest information from
destination)
Select the route with better metric when sequence numbers are equal.
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DSDV (Table Entries)
Sequence number: originated from destination. Ensures
loop freeness.
Install Time: when entry was made (used to delete stale entries from table)
Stable Data: Pointer to a table holding information on how stable a route is.
Used to damp fluctuations in network.
Destination Next Metric Seq. Nr Install Time Stable Data
A A 0 A-550 001000 Ptr_A
B B 1 B-102 001200 Ptr_B
C B 3 C-588 001200 Ptr_C
D B 4 D-312 001200 Ptr_D
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57. DSDV- ADVANTAGES AND DISADVANTAGES
Advantages
Simple (almost like Distance Vector)
Loop free through destination seq. numbers
No latency caused by route discovery
Disadvantages
No sleeping nodes
Overhead: most routing information never used
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58. DYNAMIC SOURCE ROUTING (DSR) PROTOCOL
DSR is a source initiated on-demand (or reactive) routing protocol for ad hoc
networks.
It uses source routing, technique in which sender of a packet determines the
complete sequence of nodes through which a packet has to travel.
The sender of the packet then explicitly records this list of all nodes in the packet’s
header.
Not exchange the routing table information periodically
Each mobile node in the protocol maintains a routing cache – which contains the
list of all routes that the node has learnt and maintains a sequence counter called
request id to uniquely identify the last request it had generated.
DSR works in two phases:
I. Route discovery
II. Route maintenance
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59. Route discovery -
First checks its own routing cache. If there is a
valid route, sends put the packet other wise
It initiate the route discovery by route request
The route request packet initiates a route
reply wither by the destination node of by an
intermediate node that knows a route to the
destination.
Route maintenance
Route maintenance is the process of monitoring
the correct operation of a route in use and
taking the corrective action when needed.
As soon as the source receives the RouteError
message, it deletes the broken-link-route from
its cache.
If it had another route to the destination, it
starts to retransmits the packets using
alternative route otherwise it intimates the
route discovery process again.
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60. DYNAMIC SOURCE ROUTING: ADVANTAGES AND DISADVANTAGES
Advantages
Routes maintained only between nodes who need to communicate
reduces overhead of route maintenance
Route caching can further reduce route discovery overhead
A single route discovery may yield many routes to the destination, due to intermediate nodes replying
from local caches
Disadvantages
Packet header size grows with route length due to source routing
Flood of route requests may potentially reach all nodes in the network
Potential collisions between route requests propagated by neighboring nodes
insertion of random delays before forwarding RREQ
Increased contention if too many route replies come back due to nodes replying using their local cache
Route Reply Storm problem
Stale caches will lead to increased overhead
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61. AD HOC ON-DEMAND DISTANCE VECTOR ROUTING (AODV)
DSR includes source routes in packet headers
Resulting large headers can sometimes degrade performance particularly when data
contents of a packet are small
AODV attempts to improve on DSR by maintaining routing tables at the nodes, so
that data packets do not have to contain routes
AODV retains the desirable feature of DSR that routes are maintained only between
nodes which need to communicate
Route Requests (RREQ) are forwarded in a manner similar to DSR
When a node re-broadcasts a Route Request, it sets up a reverse path pointing
towards the source
AODV assumes symmetric (bi-directional) links
When the intended destination receives a Route Request, it replies by sending a
Route Reply (RREP)
Route Reply travels along the reverse path set-up when Route Request is forwarded
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62. ZONE ROUTING PROTOCOL (ZRP)
ZRP combines proactive and reactive approaches –hybrid Protocol.
It incorporates the merits of both on demand and proactive protocols
All nodes within hop distance at most d from a node X are said to be in
the routing zone of node X
All nodes at hop distance exactly d are said to be peripheral nodes of node
X’s routing zone
Intra-zone routing: Proactively maintain routes to all nodes within the
source node’s own zone.
Inter-zone routing: Use an on-demand protocol (similar to DSR or AODV)
to determine routes to outside zone.
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63. ZONE ROUTING PROTOCOL (ZRP)
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Radius of routing zone = 2
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64. MULTICAST ROUTING PROTOCOLS FOR MANET
• Multicast is the delivery of a message to a group of destination
nodes in a single transmission as shown in figure
• Providing efficient bandwidth, Reducing communication cost,
Efficient delivery of data, Supporting dynamic topology Multiple
uncast
• Minimizing network load ,Providing basic support for reliable
transmission, Designing optimal routes, Providing robustness,
efficiency, and adaptability
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There are two main categories of multicast routing protocols: Tree-based protocols, and Mesh-based
protocols
Tree-based protocols : Establish a single path between any two nodes in the multicast group. Minimum
number of copies per packet to be sent in the tree. Bandwidth efficient .
Example Multicast Ad hoc On-Demand Distance Vector (MAODV) routing protocol
Mesh-based protocols : Establish a mesh of paths that connect the sources and destinations. They are more
resilient to link failures as well as to mobility. Drawback – Multiple copies of the same packet are
disseminated through the mesh., resulting in reduced packet delivery and increased overhead under
highly mobilized conditions.
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65. VEHICULAR AD HOC NETWORKS(VANET)
VANET is a special type of MANET in which moving automobiles from the
nodes of the network
Vehicle can communicate with other vehicle that are within a range of about
100 to 300 meters – Multi- hop communication.
Any vehicle that goes out of the signal range in the network excluded from
the network.
A vehicle come in the range of a vehicles of a VANET can come in the range
can join the network
A VANET can offer a significant utility value to a motorist.
It can help drivers to get information and warnings from a nearby
environment via message exchange
It can help disseminate geographical information to drivers as he continues
tor drive
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66. The driver can get road condition ahead or a warning about the application of
emergency electronic brake by a vehicle ahead in the lane.
Drivers may have the opportunity to engage in other leisurely tasks, VoIP with
family, watch news and participate in an office video conference etc
Two vehicles are involved in a collision. The trailing vehicle get advance
notification of the collision ahead on the road. The scenario shown in figure.
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67. MANET VS VANET
MANET VANET
A mobile ad-hoc network (MANET) is a self-configuring
infrastructure- less network of mobile devices connected
by wireless.
Vehicular Ad hoc Network (VANET) is a subclass of
mobile Ad Hoc networks (MANETs)
Each device in a MANET is free to move independently
in any direction, and will therefore change its links to
other devices frequently
These networks
have no fixed infrastructure and instead rely on the
vehicles themselves to provide network functionality.
Dynamic topologies
• variable capacity links
• Energy constrained operation
• Limited physical security
The very high speed of the nodes
Vehicles that are not subjected to the strict energy,
space and computing capabilities restrictions
he VANET nodes are not subject to storage and power
limitation.
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68. SECURITY
MANETs are much more vulnerable to attack than wired network. This is because of the following reasons :
Open Medium - Eavesdropping is more easier than in wired network.
Dynamically Changing Network Topology – Mobile Nodes comes and goes from the network , thereby
allowing any malicious node to join the network without being detected.
Cooperative Algorithms - The routing algorithm of MANETs requires mutual trust between nodes which
violates the principles of Network Security.
Lack of Centralized Monitoring - Absence of any centralized infrastructure prohibits any monitoring agent in
the system.
Lack of Clear Line of Defense –
The important characteristics of ad hoc networks that can be exploited to cause security
vulnerabilities
• Lack of physical boundary – difficult to deploy firewalls or monitor the incoming traffic.
• Low power RF transmission – signal jamming lead to denial of service(DoS) attack
• Limited computational capabilities- Inability to encrypt messages – spoofing and routing
attacks.
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69. CHARACTERISTICS OF SECURE AD HOC NETWORKS
A secure ad hoc network should have the following characteristics
Availability – able to survive denial of service(DOS)
Confidentiality- Prevent unauthorized users to access confidential
information
Integrity- no tampering of transmitted messages.
Authentication – Guarantee about the true identity of peer node
Non-repudiation- Should ensure that a node having sent a message
can not deny it.
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