Post on 17-Jan-2016
transcript
Ad Hoc Network
Outline
Introduction Benefits Applications Security Issues Routing protocols in Ad-hoc
network
Introduction Ad Hoc network is a collection of
wireless mobile hosts forming a temporary network without the aid of any established infrastructure or centralized administration Machines may join and leave the network
at any time Machines are mobile; movement is
entirely unrestricted Each machine forwards data packets for
other machines in the network
Introduction The transmission of a host is
received by all hosts within its transmission range due to the broadcast nature of wireless communication and omni-directional antennae.
If two wireless hosts are out of their transmission ranges in the ad hoc networks, other hosts located between them can forward their messages, which effectively builds connected networks among the mobile hosts in the deployed area.
Introduction
A B C
C is out of the wireless transmission range of A
A and C need the help of B to exchange packets
A Simple Ad Hoc Wireless Network
Introduction
Ad Hoc Network Consists of mobile
hosts (or nodes) which communicate with other nodes through wireless medium without any fixed infrastructure( like AP in 802.11)
Introduction Dynamic network topology
The mobile nodes are free to move randomly and organize themselves arbitrarily; thus, the network's wireless topology may change rapidly and unpredictably.
move
A
Radio range of A
A
Radio range of A
Characteristics and tradeoffs Characteristics
Self-organized Self-deployed Decentralized Dynamic network topology
Tradeoffs Limited Bandwidth Need Multi-hop router Energy consumption problem Security problem
Benefits
Easy to deployment
Fast deployment
No dependence on infrastructure
Applications Personal area networking
Cell phone, laptop, PDA , tablet pc Emergency operations
Search and rescue Policing and fire fighting
Civilian environments Taxi cab network Boats, aircrafts
Military use On the battle field
Personal area networking Cell phone, laptop, PDA , tablet pc
Military use
Civilian Applications
Disaster Recovery (flood, fire, earthquakes etc)
Homeland defense Search and rescue in remote
areas Environment monitoring
(sensors) Space/planet exploration
An ad-hoc network as a graph
Critical issues in ad hoc networking
Routing: Efficient: minimize control update O/H and
redundant forwarding robust, QoS enabled routing route security, covert operations
Security: Multicast:
congestion controlled; reliable
Security Issues Security is an important issue for ad
hoc networks, especially for those security-sensitive applications.
we consider the following attributes: Availability Confidentiality Integrity Authentication Non-repudiation.
Availability Keep the network alive against denial of
service attacks. A denial of service attack could be launched at any layer of an ad hoc network. physical and media access control layers
Jamming the wireless channel network layer
disrupt the routing protocol and disconnect the network.
higher layers bring down high-level services. One such target is
the key management service, an essential service for any security framework.
Confidentiality Some sensitive information requires
confidentiality Ex. Strategic or tactical military information
Leakage of such information could be dangerous , therefore we need to protect these information
Routing information must also remain confidential in some cases, because the information might be used to track any node by an adversary.
Integrity
Guarantees that a message being transferred is never corrupted.
A message could be corrupted because of radio propagation impairment, or because of malicious attacks on the network.
Authentication
Enables a node to ensure the identity of the peer node it is communicating with.
Without authentication, an adversary could masquerade a node, thus gaining unauthorized access to resource and sensitive information and interfering with the operation of other nodes.
Non-repudiation Ensures that the origin of a message
cannot deny having sent the message. Non-repudiation is useful for detection
and isolation of compromised nodes. When a node A receives an erroneous
message from a node B, non-repudiation allows A to accuse B using this message and to convince other nodes that B is compromised by an adversary.
Ad-hoc routing protocols
Ad-hoc routing protocols
Source-initiated On-demand Driven
Table Driven
AODV LMR ABR DSR
TORA SSR
WRPDSDV
CGSR
Source-Initiated On-Demandrouting protocols
Source-Initiated On-Demand routing AODV: Ad-hoc On-Demand Distance Vector
Routing DSR: Dynamic Source Routing
Generate routes when desired by the source node.
Packet on source node must wait until a route is discovered.
Periodic route updates are not required.
Table-Driven routing protocols
Table-Driven routing protocols : DSDV: Destination-sequenced Distance-
vector Routing Every node need to maintain a table to
store routing information. Require mechanisms to update the
routing table periodically Cause signaling traffic and power
consumption problems Packets on source can be forwarded
immediately since the routes are always available.