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Chapter 5: OSPF Configuration Guide
5 - 4 SSR User Reference Manual
Configure an OSPF Area
OSPF areas are a collection of subnets that are grouped in a logical fashion. These
areas communicate with other areas via the backbone area. Once OSPF areas are
created, you can add interfaces, stub hosts, and summary ranges to the area.
In order to reduce the amount of routing information propagated between areas, you
can configure summary-ranges on Area Border Routers (ABRs). On the SSR,
summary-ranges are created using the
ospf add network
command – the networks
specified using this command describe the scope of an area. Intra-area Link State
Advertisements (LSAs) that fall within the specified ranges are not advertised into
other areas as inter-area routes. Instead, the specified ranges are advertised as summary
network LSAs.
To create areas and assign interfaces, enter the following commands in the Configure
mode.
Configure OSPF Area Parameters
The SSR allows configuration of various OSPF area parameters, including stub areas,
stub cost and authentication method. Stub areas are areas into which information on
external routes is not sent. Instead, there is a default external route generated by the
ABR, into the stub area for destinations outside the autonomous system. Stub cost
specifies the cost to be used to inject a default route into a stub area. An authentication
method for OSPF packets can be specified on a per-area basis.
Create an OSPF area.
ospf create area <area-num>|backbone
Add an interface to an OSPF area.
ospf add interface <
name-or-IPaddr>
[to-area <area-addr>|backbone] [type
broadcast|non-broadcast]
Add a stub host to an OSPF area.
ospf add stub-host [to-area <area-
addr>|backbone] [cost <num>]
Add a network to an OSPF area for
summarization.
ospf add network <IPaddr/mask> [to-area
<area-addr>|backbone] [restrict] [host-
net]