User Manual

Configuring OSPF
186 Enterasys X-Pedition User Reference Manual
Configuring OSPF Area Parameters
The XP allows configuration of various OSPF area parameters, including stub areas, stub cost and
authentication method. Information about routes which are external to the OSPF routing domain is
not sent into a stub area. Instead, there is a default external route generated by the ABR into the
stub area for destinations outside the OSPF routing domain. To further reduce the number of link
state advertisements sent into a stub area, you can specify the no-summary keyword with the stub
option on the ABR to prevent it from sending summary link advertisement (link state
advertisements type 3) into the stub area.
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.
To configure OSPF area parameters, enter the following commands in the Configure mode.
Note: Although this does not apply to most changes to OSPF and other routing-based entries in
the configuration file, the following actions force the OSPF Link State Databases (LSDB)
to re-initialize:
• Adding a network to or removing one from an area.
• Changing an area’s type.
• Adding a summary range to or removing one from an Area Border Router.
Creating Virtual Links
In OSPF, virtual links can be established:
• To connect an area via a transit area to the backbone
• To create a redundant backbone connection via another area
Each Area Border Router must be configured with the same virtual link. Note that virtual links
cannot be configured through a stub area.
Specify an OSPF area to be a stub area.
ospf set area <area-num> stub [no-summary]
Specify the cost to be used to inject a default
route into a stub area.
Note: If this command is not specified, no
default route is injected into the
OSPF stub area.
ospf set area <area-num> stub-cost <num>
Specify the authentication method to be used
by neighboring OSPF routers.
ospf set area <area-num> [stub] [authentication-method
none|simple|md5]