Ospf - D-Link DFL-1600 User Manual

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Bandwidth
– Bandwidth is the traffic capacity of a path, rated by "Mbps".
Load
– Load refers to the usage of a router. The usage can be evaluated by
CPU utilization and the throughput.
Delay
– Delay is regarding to the time it takes to move a packet from the
source to the destination. The time depends on many factors, such as
the bandwidth, load, and the length of the path.
Different routing protocols rely on one or several metrics to examine and
evaluate the links in the network. Regarding the goals of the design, the
algorithm uses its metrics to decide the optimal paths.
10.3.3

OSPF

OSPF is the embedded dynamic routing algorithm in D-Link firewalls.
From the previous section, we see the main characteristics of OSPF as a
Link state routing algorithm. Now we look at the actual operation of this
algorithm.
Areas & Routers
OSPF features hierarchical routing to give better support to complex
network environment. Since today's network is getting more and more
sophisticated, the size of the whole routing table, time required for routing
computation, and the traffic for information exchange for a large network
become excessive. OSPF enables the administrator to partition the
AS(autonomous system) into several smaller areas, so that the burden for
routing computation and routes maintenance on each router is reduced.
An OSPF area is a group of computer hosts and routers within an AS,
identified by a unique
with the format of an IP address.
On top of the OSPF hierarchy is a central area called
which all the other areas in the AS must connect. The backbone area is
responsible for distributing routing information among all the connecting
areas and has the area ID 0.0.0.0. In some cases where it is not possible to
physically connect to the backbone area, a
, and every OSPF router has a unique
D-Link Firewalls User's Guide
Chapter 10. Routing
to
can be