OSPF Area Transit Capability

Feature History for OSPF Area Transit Capability

This table provides release and platform support information for the features explained in this module.

These features are available in all the releases subsequent to the one they were introduced in, unless noted otherwise.

Release

Feature Name and Description

Supported Platform

Cisco IOS XE 17.18.1

OSPF Area Transit Capability: The OSPF Area Transit Capability is an enhancement feature that allows any OSPF area, other than Area 0 (backbone area), to act as a transit area.

Cisco C9350 Series Smart Switches

Cisco C9610 Series Smart Switches

OSPF Area Transit Capability

The OSPF Area Transit Capability is an enhancement feature that allows any OSPF area, other than Area 0 (backbone area), to act as a transit area. A transit area can forward traffic that does not originate nor terminate within the area.

How OSPF Area Transit Capability works

By default, only Area 0 is used for inter-area transit traffic. Sometimes, devices in non-backbone areas can provide a shorter path for traffic between other areas. With Area Transit Capability enabled, an OSPF Area Border Router (ABR) can recognize and use these shorter transit paths through non-backbone areas. This may provide more optimal routing compared to virtual links, which are normally used to connect non-backbone areas to Area 0.

Disable OSPF Area Transit Capability on an ABR

OSPF area capability is enabled by default. To disable OSPF area transit capability on an ABR, perform this procedure.

Procedure

Step 1

enable

Example:

Device> enable

Enables privileged EXEC mode.

Enter your password, if prompted.

Step 2

configure terminal

Example:

Device# configure terminal

Enters global configuration mode.

Step 3

router ospf process-id [vrf vrf-name]

Example:

Device(config)# router ospf 15

Enables OSPF routing and enters router configuration mode.

  • process-id : The process ID is an internally used identification parameter that is locally assigned. Each OSPF process has a unique process ID.

    Process ID can be a positive integer from 1 to 65535.

  • vrf: Indicates that the OSPF process is being configured for a specific VRF.

  • vrf-name : Specifies the name of the VRF for which this OSPF process is being created.

Step 4

no capability transit

Example:

Device(config-router)# no capability transit

Disables OSPF area transit capability on all areas for an OSPF process.

Step 5

end

Example:

Device(config-router)# end

Returns to privileged EXEC mode.

Configuration example for OSPF Area Transit Capability

This example shows how to disable OSPF Area Transit Capability.


Device> enable
Device# configure terminal
Device(config)# router ospf 15
Device(config-router)# no capability transit