Edge-Core ECS4660-28F Management Manual page 790

Hide thumbs Also See for ECS4660-28F:

Table of Contents

| Unicast Routing

Configuring the Open Shortest Path First Protocol (Version 2)

You can further optimize the exchange of OSPF traffic by specifying

an area range that covers a large number of subnetwork addresses.

This is an important technique for limiting the amount of traffic

exchanged between Area Border Routers (ABRs).

And finally, you must specify a virtual link to any OSPF area that is

not physically attached to the OSPF backbone. Virtual links can also

be used to provide a redundant link between contiguous areas to

prevent areas from being partitioned, or to merge backbone areas.

(Note that virtual links are not supported for stubs or NSSAs.)

OSPF protocol broadcast messages (i.e., Link State Advertisements or

LSAs) are restricted by area to limit their impact on network performance.

A large network should be split up into separate OSPF areas to increase

network stability, and to reduce protocol traffic by summarizing routing

information into more compact messages. Each router in an area shares

the same view of the network topology, including area links, route

summaries for directly connected areas, and external links to other areas.

Use the Routing Protocol > OSPF > Network Area (Add) page to define an

OSPF area and the interfaces that operate within this area. An autonomous

system must be configured with a backbone area, designated by the area

identifier 0.0.0.0. By default, all other areas are created as normal transit

Routers in a normal area may import or export routing information about

individual nodes. To reduce the amount of routing traffic flooded onto the

network, an area can be configured to export a single summarized route

that covers a broad range of network addresses within the area

805). To further reduce the amount of routes passed between areas,

an area can be configured as a stub

Normal Area – A large OSPF domain should be broken up into several areas

to increase network stability and reduce the amount of routing traffic

required through the use of route summaries that aggregate a range of

addresses into a single route. The backbone or any normal area can pass

traffic between other areas, and are therefore known as transit areas. Each

router in an area has identical routing tables. These tables may include

area links, summarized links, or external links that depict the topology of

the autonomous system.

Figure 485: OSPF Areas

802) or a not-so-

Chapters

Table of Contents