General Operation Of Ospf - Hirschmann MACH 4000 User Manual

OSPF

7.2 General Operation of OSPF

OSPF was specially tailored to the needs of larger networks and provides a
fast convergence and minimum usage of protocol messages.
The concept of OSPF is based on the creation, maintenance and distribution
of what is called the link state database. This data basis describes
all the routers within a routing domain (area) and
their active interfaces and routes,
how they are linked to each other and
the costs of these links.
All the routers within an area have an identical data basis, which means that
they all know the exact topology within this area.
Every router plays its part in setting up the respective data basis by
propagating its local viewpoint as Link State Advertisements (LSAs).
These LSAs are then flooded to all the other routers within an area.
OSPF supports a range of different network types such as point-to-point
networks (for example, packet over SONET/SDH), broadcast networks
(Ethernet) or non-broadcast networks.
Broadcast networks are distinguished by the fact that a number of systems
(terminal devices, switches, routers) are connected to the same segment and
thus can all be addressed simultaneously via broadcasts/multicasts.
OSPF generally performs the following three steps in carrying out its tasks in
the network:
Setting up the neighbor relationships (hello protocol)
Synchronizing the link state database
Route calculation
Routing L3P
Release 4.0 11/07
7.2 General Operation of OSPF
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