Open Shortest Path First Protocol (Ospf) - Bay Networks Nautica 200 Reference Manual

Open Shortest Path First (OSPF)
117237-C Rev. A
A call that has been made for data transfer will not be kept open
by routing updates, because these are not included in the idle
calculation for that call. All routing updates received while the
connection is closed are copied to the local routing table(s), and
the table information is transferred automatically when the next
call is made.
These mechanisms, specifically related to ISDN connectivity,
combine to ensure that unnecessary calls are not made and that
call duration is kept to a minimum.
The Nautica 4000 and Marlin support OSPF, a protocol designed
to remove some of the restrictions of RIP in large networks,
especially in the IP environment.
While RIP is a distance-based protocol which uses hop count as
its only decision criteria and sends out routing updates every 30
seconds, ignoring network changes, OSPF is a Link State
Shortest Path First Protocol which records the state of an
interface and any changes to that interface. Such changes then
cause a routing update message to be sent. This greatly reduces
the number of messages on the internetwork. OSPF update
messages are also smaller in size, carrying only the changes to the
routing environment, rather than the whole routing table as in
RIP. This means a significant bandwidth saving on the
internetwork.
However, OSPF routers need a more powerful CPU and more
memory to process the greater amount of information generated.
The Nautica series is ideal for OSPF due to its use of RISC-based
processors, which can be scaled up easily to handle both medium
and large network topologies.
Understanding the Technology
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