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3 ospf – Planet Technology WGS3-2840 User Manual

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4.5.3 OSPF

This section provides OSPF function from Layer 3 Managed Switch. OSPF (Open Shortest Path First) is a router protocol
used within larger autonomous system networks in preference to the Routing Information Protocol (RIP), an older routing
protocol that is installed in many of today's corporate networks. Like RIP, OSPF is designated by the Internet Engineering
Task Force (IETF) as one of several Interior Gateway Protocols (IGPs).

Using OSPF, a host that obtains a change to a routing table or detects a change in the network immediately multicasts the
information to all other hosts in the network so that all will have the same routing table information. Unlike the RIP in which
the entire routing table is sent, the host using OSPF sends only the part that has changed. With RIP, the routing table is
sent to a neighbor host every 30 seconds. OSPF multicasts the updated information only when a change has taken place.

Rather than simply counting the number of hops, OSPF bases its path descriptions on "link states" that take into account
additional network information. OSPF also lets the user assign cost metrics to a given host router so that some paths are
given preference. OSPF supports a variable network subnet mask so that a network can be subdivided. RIP is supported
within OSPF for router-to-end station communication. Since many networks using RIP are already in use, router manu-
facturers tend to include RIP support within a router designed primarily for OSPF. The OSPF screen in

Figure 4-38

appears

and

Table 4-10

descriptions the OSPF Configuration Web page objects.

Figure 4-38 OSPF Configuration Web Page screen

Table 4-10 Descriptions of OSPF Web Page screen Objects

Object

Description

Router-ID

Allow input the Router ID.

IP Address

Allow input the IP address for the entry.

Subnet Mask

Allow input the subnet mask value for the entry. If this field is zero, no subnet mask has been
specified for the entry.

Area (0-4294967295)

Allow input the Area value and available range is 0-4294967295.

OK

Click this button to take affect.