Mobile Ad hoc Networks A General Perspective

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Mobile Ad hoc NetworksA General Perspective

• Srivas N. Chennu
• Vishwas N.
• 8th Semester CSE
• RVCE

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What Are MANETs ?

• Interconnected collection of wireless nodes
• Nodes enter and leave over time
• Nodes also act as routers forward packets
• No pre-established network infrastructure
• No centralized administration
• Communication using BlueTooth and WAP

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Characteristics Of MANETs

• Dynamic Topologies and node memberships
• Bandwidth constraints
• Many Transmission Errors
• Energy-constrained operation

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Where Could We Use MANETs ?

• Industrial and commercial networks
• Anywhere communication
• Military applications
• Robust alternatives to cellular networks
• Wearable and Ubiquitous computing
• Remote satellite - based communication

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What About Mobile IP ?
Mobile Node in the Home Network managed by Home
Agent.
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Mobile Node moves to Foreign Network. HA tunnels
packets to FA and intimates Correspondent Node S.
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A Typical MANET
A
A
B
B
Overlap of Transmission Ranges of Nodes allows
Packet Forwarding
Packets travel over multiple wireless hops
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MANETs and the Internet

• Future goal seamless net connectivity
• Mobile IP needs to be modified
• Common interfacing between BlueTooth, WAP and IP
• User applications
• Need for handheld and portable computing devices

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Routing Protocols

• Proactive protocols
• Distributed shortest-path protocols
• Maintain routes between every host pair at all
  times
• Based on periodic updates
• Reactive protocols
• Determine route if and when needed
• Source initiates route discovery
• Hybrid protocols
• Adaptive Combination of proactive and reactive

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Proactive Destination Sequenced Distance-Vector

• Each node maintains a routing table
• Next hop, cost metric towards each destination
• Sequence num created by the destination itself
• Each node forwards routing table to neighbors
• Each node increments and appends its sequence
  number when sending its local routing table
• Routes with greater sequence numbers are preferred

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• X receives information from Y about a route to Z
• Let destination sequence number for Z at X be
  S(X), S(Y) is sent from Y
• If S(X) gt S(Y), then X ignores the routing
  information received from Y
• If S(X) S(Y), and cost of going through Y is
  smaller than the route known to X, then X sets Y
  as the next hop to Z
• If S(X) lt S(Y), then X sets Y as the next hop to
  Z and S(X) is updated to equal S(Y)

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Reactive Dynamic Source Routing Route Discovery
Represents transmission of Route Request (RREQ)
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Route Discovery in DSR
S
E
F
S,E,F,J
B
C
M
L
J
A
G
H
D
K
I
N
S,C,G,K

• Node D does not forward RREQ, because node D
• is the intended target of the route discovery

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Route Reply in DSR
S
RREP S,E,F,J,D
E
F
B
C
M
L
J
A
G
H
D
K
I
N
Represents Route Reply (RREP) control message
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Data Delivery in DSR
DATA S,E,F,J,D
S
E
F
B
C
M
L
J
A
G
H
D
K
I
N
Represents data packet
Packet header size grows with route length
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Hybrid Zone Routing Protocol
Radius of routing zone 2 Intra-Zone
Proactive Inter-Zone Reactive
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Current Issues in MANETs

• Security
• Vulnerability of Wireless Links
• MANET node authentication policies
• RSA based encryption using shared certificate
  authorities
• Quality of Service
• VCs and Bandwidth Reservation
• Dynamic RSVP

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Conclusion

• References
• E.M. Royer and C.K. Toh, A Review of Current
  Routing Protocols for Ad-Hoc Mobile Wireless
  Networks
• Charles E. Perkins, Mobile IP Design Principles
  and Practice
• S. Corson J. Macker, Mobile Ad hoc Networking
  (MANET) Routing Protocol Performance Issues and
  Evaluation Considerations RFC 2501