The document discusses the Dynamic Source Routing (DSR) protocol. It divides the routing task into two problems - route discovery, where a node discovers a route to a destination if it needs to send data to that destination, and route maintenance, where if a node is continuously sending packets via a route it must ensure the route is valid. DSR eliminates periodic routing updates. It uses route requests that are broadcasted with a unique identifier and destination, and collects addresses of traversed nodes to build paths. It has advantages like maintaining routes only between communicating nodes, and route caching can reduce overhead, but also has disadvantages like increased packet header size and potential collisions during route requests.

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INTRODUCTION
Routing is the
process of selecting
paths in a network
along which to send
network traffic.
Routing directs
packet forwarding,
the transit of
logically addressed
packets from their
source toward their
ultimate destination
through intermediate
nodes.
Packet is a
formatted unit of
data.
-Pallavi Anand

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DSR
'Dynamic Source
Routing' (DSR) is
a routing protocol
for wireless mesh
networks.
It divides the task
of routing into two
separate
problems.
Route
Discovery
Route
Maintenance

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1. ROUTE DISCOVERY
A node tries to
discover a route
to a destination if
it has to send
something to this
destination and
there is currently
no known route.

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2. Route Maintenance
If a node is continuously sending
packets via a route, it has to make
sure that the route is held upright. As
soon as node detects problems with
the current route, it has to find an
alternative.

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DSR eliminates all the
periodic routing updates.
If a node needs to discover
a route, it broadcasts a
route request with a unique
identifier and the destination
address as parameters.

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3. Otherwise, the node
appends its own address to
a list of transverse hops in
the packet and broadcast
this updated route request.
2. If the node recognizes its
own address as destination,
the request has reached the
target.
Any node that
receives a route
request does the
following.
1. If the node had
already received
the request it drops
the request packet.

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Using this approach,
the route request
collects a list of
addresses representing
a possible path towards
the destination.
Request
Number
Destination
Address
Source
Address

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As soon as the request reaches the
destination it can return the request
packet containing the list to receiver
using this list in reverse order

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Broadcast transmission
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Dynamic Source Routing: 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

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DSR: 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
Increased
contention if too
many route
replies come back
due to nodes
replying using
their local cache

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THANK YOU..