.. _ug:cha:adhoc-routing:

Ad Hoc Routing
==============

.. _ug:sec:adhocrouting:overview:

Overview
--------

In ad hoc networks, nodes are not familiar with the topology of their
networks. Instead, they have to discover it: typically, a new node
announces its presence and listens for announcements broadcast by its
neighbors. Each node learns about others nearby and how to reach them,
and may announce that it too can reach them. The difficulty of routing
may be compounded by the fact that nodes may be mobile, which results in
a changing topology.

Ad hoc routing protocols fall in two broad categories: proactive and
reactive. *Proactive* or *table-driven* protocols maintain fresh lists
of destinations and their routes by periodically distributing routing
tables throughout the network. *Reactive* or *on-demand* protocols find
a route on demand by flooding the network with Route Request packets.

The INET Framework contains the implementation of several ad hoc routing
protocols including :protocol:`AODV`, :protocol:`DSDV`, :protocol:`DYMO`
and :protocol:`GPSR`.

The easiest way to add routing to an ad hoc network is to use the
:ned:`ManetRouter` NED type for nodes. :ned:`ManetRouter` contains a
submodule named ``routing`` whose type is a parameter, so it can be
configured to be an AODV router, a DYMO router, or a router of any other
supported routing protocol. For example, you can configure
:ned:`ManetRouter` nodes in the network to use AODV with the following
ini file line:



.. code-block:: ini

   **.routingApp.typename = "Aodv" # as an application
   **.routing.typename = "Gpsr" # as a routing protocol module

There are also NED types called :ned:`AodvRouter`, :ned:`DymoRouter`,
:ned:`DsdvRouter`, :ned:`GpsrRouter`, which are all :ned:`ManetRouter`’s
with the routing protocol submodule type set appropriately.

.. _ug:sec:adhocrouting:aodv:

AODV
----

AODV (Ad hoc On-Demand Distance Vector Routing) is a routing protocol
for mobile ad hoc networks and other wireless ad hoc networks. It offers
quick adaptation to dynamic link conditions, low processing and memory
overhead, low network utilization, and determines unicast routes to
destinations within the ad hoc network.

The :ned:`Aodv` module type implements AODV, based on RFC 3561.

:ned:`AodvRouter` is a :ned:`ManetRouter` with the routing module type
set to :ned:`Aodv`.

.. _ug:sec:adhocrouting:dsdv:

DSDV
----

DSDV (Destination-Sequenced Distance-Vector Routing) is a table-driven
routing scheme for ad hoc mobile networks based on the Bellman-Ford
algorithm.

The :ned:`Dsdv` module type implements DSDV. It is currently a partial
implementation.

:ned:`DsdvRouter` is a :ned:`ManetRouter` with the routing module type
set to :ned:`Dsdv`.

.. _ug:sec:adhocrouting:dymo:

DYMO
----

The DYMO (Dynamic MANET On-demand) routing protocol is successor to the
AODV routing protocol. DYMO can work as both a pro-active and as a
reactive routing protocol, i.e. routes can be discovered just when they
are needed.

The :ned:`Dymo` module type implements DYMO, based on the IETF draft
*draft-ietf-manet-dymo-24*.

:ned:`DymoRouter` is a :ned:`ManetRouter` with the routing module type
set to :ned:`Dymo`.

.. _ug:sec:adhocrouting:gpsr:

GPSR
----

GPSR (Greedy Perimeter Stateless Routing) is a routing protocol for
mobile wireless networks that uses the geographic positions of nodes to
make packet forwarding decisions.

The :ned:`Gpsr` module type implements GPSR, based on the paper “GPSR:
Greedy Perimeter Stateless Routing for Wireless Networks” by Brad Karp
and H. T. Kung, 2000. The implementation supports both GG and RNG
planarization algorithms.

:ned:`GpsrRouter` is a :ned:`ManetRouter` with the routing module type
set to :ned:`Gpsr`.