| dc.description.abstract | Current wireless networks only allow users a limited freedom of
mobility. This follows from the observation that these networks typically rely on
existing infrastructure such as access points. To overcome this
restriction, a new type of wireless networks is emerging - the Mobile Ad
Hoc Network (MANET). MANETs are infrastructure-less, self-configuring
networks that consist of mobile nodes moving in an arbitrary fashion.
During the past few years, MANETs have been subject to heavy investigation by both the
academic and the industrial communities. Various research efforts have resulted in
numerous routing protocols for such networks which are originally assumed to run in
a standalone fashion. A recent growing trend in ad hoc networking, however,
indicates that the inter-networking between MANETs and existing wired
networks, e.g. the Internet, is an interesting topic of practical importance. Being a
standard interior routing protocol widely deployed in the global Internet, Open
Shortest Path First (OSPF) appears to be the most promising routing solution, not only
for inter-connected MANETs, but also for standalone ad hoc networks.
This master thesis deals with the topic of how to extend OSPF for IPv6 (known as
OSPFv3) for (enhanced) operation in MANETs. Based on an OSPF-MANET extension
proposal published by Cisco Systems as an Internet-draft, referred to as
\emph{Overlapping Relays (OR)}, the thesis has designed and implemented the scheme
which consists of several mechanisms for wireless extensions of OSPF.
Aiming at reducing routing overhead imposed on MANETs, the OR proposal adopts the
MultiPoint Relay (MPR) functionality of the Optimized Link State
Routing (OLSR) protocol for optimized flooding in such networks, but ensures the
reliable transmission assumed by OSPF.
\emph{Incremental Hellos}, a mechanism for reducing
the size of Hello packets by signaling only \emph{changes} in state, is also
defined. The above mechanisms call for exchanging additional
information on a link, and is implemented by means of Link Local
Signaling (LLS); Existing OSPFv3 packets are appended by a special data
block carrying the extra information, thus preserving the format of
these packets.
These wireless extensions are implemented by modifying and extending
the OSPFv3 source code shipped with the Quagga routing software
suite. One design objective is to reuse parts of the UniK OLSR source
code, which is done when implementing the overlapping relays
mechanism. Another design objective is to minimize changes to the existing
OSPFv3 source code, which for the most part is accomplished by
having the extensions code reside in separate files.
The work on this thesis has produced a working implementation of the wireless
extensions described in the above mentioned draft, and a testbed has been
used for proving the implementation's correctness and operability. Issues regarding
the design, implementations, as well as the draft itself, are presented in details
in the thesis. | nor |