According to the figure above, Interior
gateway protocols (IGPs) are used to enable routers exchange routing
information among themselves in the same autonomous systems (AS). An AS
consists of a group of networks that are solely managed by a single organization.
Exterior gateway protocols (EGPs), on the other hand are used to enable
different autonomous systems to communicate. An example of exterior gateway
protocol is the border gateway protocol (BGP).
Interior gateway protocols differ in routing
behavior and are further classified into
Distance Vector Protocols, Link State
Protocols and Hybrid Protocols (Kaur et al, 2014). Distance vector protocols
determine best paths to a remote network on the basis of distance.
Whenever a router forwards packets to another
router, it is termed as a hop. The path that has the least number of hops to
reach the remote network is taken as the best path. The vector points to the
direction to reach the remote network. RIPv1, RIPv2, and IGRP all fall under distance
vector protocols. Link state protocols operate on a different principle. They
create three different tables which they use in their routing process. The
first table is used to store all networks directly connected to the routers.
The second table is used to store the map of the complete internetwork. The
third table is the routing table which is used to store the shortest path to
reach all remote networks in the entire internetwork. The main distinction
between these two routing algorithms is that in distance vector routing, the
entire routing table content is exchanged between routers that are directly
connected to each other whereas in link state routing, routers only share
routing updates which contains the state of their own links with other routers
in the network. OSPF and IS–IS are typical link state protocols.
Hybrid protocols combine some routing
characteristics of distance vector protocols and link state protocols. An
example of hybrid protocol is EIGRP (Lammle, 2007).
The focus of this thesis is on two IGPs for
IPv6: the OSPFv3 and IS–IS.
Both protocols are modified versions of OSPF
and IS–IS supported in IPv4 and have been chosen for performance evaluation for
routing some of the most frequently used applications in IPv6 networks.
1.2 Problem description
The IPv4 address space exhaustion caused by
the current growth of the internet, has given IPv6 the legitimacy and
inevitability that cannot be ignored. IPv6 is the next–generation Internet
Protocol, with a large addressing space and the future replacement for IPv4.
Even though there are different IPv6 supported
routing protocols, routing instability is found to be one of the major causes
of network degradation in internet service performance due to amount of routed
traffic. For example any disturbance in a network within a few hundreds of
milliseconds is sufficient to disrupt voice or video transmission during
protocol convergence. Voice packets for instance can be lost, delayed or suffer
from jitter causing the network to degrade in performance.
Therefore, to efficiently and effectively
route data in communication networks, implementation of a suitable routing
protocol is a critical success factor to achieve high performance.
In this thesis, performance of OSPFv3 and
IS–IS is being evaluated and compared for some applications such as:
Email and web browsing