Cisco Nexus 5000 Series NX-OS Unicast Routing Command Reference
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- Updated:
- April 10, 2014
Chapter: A Commands
A Commands
This chapter describes the Cisco NX-OS Open Shortest Path First (OSPF) commands that begin with A.
area authentication (OSPF)
To enable authentication for an Open Shortest Path First (OSPF) area, use the area authentication command. To remove authentication for an area, use the no form of this command.
area area-id authentication [ message-digest ]
no area area-id authentication [ message-digest ]
Syntax Description
Command Default
Command Modes
Command History
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Usage Guidelines
Use the area authentication command to configure the authentication mode for the entire OSPF area.
The authentication type and authentication password must be the same for all OSPF devices in an area. Use the ip ospf authentication-key command in interface configuration mode to specify this password.
If you enable MD5 authentication with the message-digest keyword, you must configure a password with the ip ospf message-digest-key command in interface configuration mode.
Examples
This example shows how to configure authentication for area 0 of OSPF routing process 201:
Related Commands
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Saves the configuration changes to the startup configuration file. |
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Assigns a password for simple password authentication for OSPF. |
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area default-cost (OSPF)
To specify a cost for the default summary route sent into an Open Shortest Path First (OSPF) stub or not-so-stubby area (NSSA), use the area default-cost command. To remove the assigned default route cost, use the no form of this command.
area area-id default-cost cost
no area area-id default-cost cost
Syntax Description
Command Default
The summary route cost is based on the area border router that generated the summary route.
Command Modes
Command History
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Usage Guidelines
Use the area default-cost command on an Area Border Router (ABR) attached to a stub or NSSA to configure the metric for the summary default route generated by the ABR into the stub area.
Examples
This example shows how to set a default cost of 20 to stub network 192.0.2.0:
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Saves the configuration changes to the startup configuration file. |
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area filter-list (OSPF)
To filter prefixes advertised in type 3 link-state advertisements (LSAs) between Open Shortest Path First (OSPF) areas of an Area Border Router (ABR), use the area filter-list command. To change or cancel the filter, use the no form of this command.
area area-id filter-list route-map map-name { in | out }
no area area-id filter-list route-map map-name { in | out }
Syntax Description
Command Default
Command Modes
Command History
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Usage Guidelines
Use the area filter-list command to filter Type 3 LSAs. If you apply the route map with the in keyword, the route map filters all Type 3 LSAs originated by the ABR to this area, including Type 3 LSAs that originated as a result of the area range command in another area.
If you apply the route map with the out keyword, the route map filters all Type 3 LSAs that are advertised by the ABR to all other areas including Type 3 LSAs that originate locally as a result of the area range command configured in this area.
Cisco Nexus 5500 implicitly denies any prefix that does not match an entry in the route map.
Examples
This example shows how to filter prefixes that are sent from all other areas to area 1:
Related Commands
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Saves the configuration changes to the startup configuration file. |
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Defines the conditions for redistributing routes from one routing protocol into another. |
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area nssa (OSPF)
To configure an area as an Open Shortest Path First (OSPF) not-so-stubby (NSSA) area, use the area nssa command. To remove the NSSA area, use the no form of this command.
area area-id nssa [ default-information-originate [ route-map map-name ]] [ no-redistribution ] [ no-summary ] [ translate type7 [ always | never ] [ suppress-fa ]]
no area area-id nssa [ default-information-originate [ route-map map-name ]] [ no-redistribution ] [ no-summary ] [ translate type7 [ always | never ] [ suppress-fa ]]
Syntax Description
Command Default
Command Modes
Command History
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Usage Guidelines
Use the area nssa command to create an NSSA area in an OSPF autonomous system. We recommend that you understand the network topology before configuring forwarding address suppression for translated LSAs. Suboptimal routing might result because there might be better paths to reach the destination’s forwarding address.
Examples
This example shows how to configure area 1 as an NSSA area:
This example shows how to configure area 1 as an NSSA area and translate Type 7 LSAs from area 1 to Type 5 LSAs, but not place the Type 7 forwarding address into the Type 5 LSAs. (OSPF places 0.0.0.0 as the forwarding address in the Type 5 LSAs.)
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Saves the configuration changes to the startup configuration file. |
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Redistributes routes learned from one routing protocol to another routing protocol domain. |
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area range (OSPF)
To consolidate and summarize routes at an Open Shortest Path First (OSPF) area boundary, use the area range command. To disable this function, use the no form of this command.
area area-id range ip-prefix [ not-advertise ]
no area area-id range ip-prefix [ not-advertise ]
Syntax Description
Command Default
Command Modes
Command History
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Usage Guidelines
Use the area range command only with Area Border Routers (ABRs) to consolidate or summarize routes for an area. The ABR advertises that a single summary route is advertised to other areas and condenses routing information at area boundaries.
You can configure OSPF to summarize addresses for many different sets of address ranges by configuring multiple area range commands.
Examples
This example shows how to configure one summary route to be advertised by the ABR to other areas for all hosts on network 192.0.2.0:
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Saves the configuration changes to the startup configuration file. |
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area stub (OSPF)
To define an area as an Open Shortest Path First (OSPF) stub area, use the area stub command. To remove the area, use the no form of this command.
area area-id stub [ no-summary ]
no area area-id stub [ no-summary ]
Syntax Description
Command Default
Command Modes
Command History
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Usage Guidelines
Use the area stub command to configure all devices attached to the stub area. Use the area default-cost command on an area border router (ABR) attached to the stub area. The area default-cost command provides the metric for the summary default route generated by the ABR into the stub area.
To further reduce the number of link-state advertisements (LSAs) sent into a stub area, you can configure the no-summary keyword on the ABR to prevent it from sending Summary LSAs (Type 3 LSAs3) into the stub area.
Examples
This example shows how to create stub area 33 in OSPF 209:
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Specifies a cost for the default summary route sent into a stub area. |
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Saves the configuration changes to the startup configuration file. |
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area virtual-link (OSPF)
To define an Open Shortest Path First (OSPF) virtual link, use the area virtual-link command. To remove a virtual link, use the no form of this command.
area area-id virtual-link router-id
no area area-id virtual-link router-id
Syntax Description
Command Default
Command Modes
Command History
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Command History
Usage Guidelines
Use the area virtual-link command to establish a virtual link from a remote area to the backbone area. In OSPF, all areas must be connected to a backbone area. If the connection to the backbone is lost, it can be repaired by establishing a virtual link.
Use the area virtual-link command to enter the virtual link configuration mode where you can use the following commands:
- authentication [key-chain | message-digest | null]
- authentication-key [0 | 3] key
- dead-interval seconds
- hello-interval seconds
- message-digest-key key-id md5 key
- retransmit-interval seconds
- transmit-delay seconds
See each command for syntax and usage details.
You must configure both sides of a virtual link with the same area ID and the corresponding virtual link neighbor router ID. To see the router ID, use the show ip ospf neighbors command in any mode.
Note
You cannot configure a virtual link on a not-so-stubby (NSSA) area.
Examples
This example shows how to establish a virtual link between two devices, A, and B, with default values for all optional parameters:
Related Commands
authentication (OSPF virtual link)
To specify the authentication type for an Open Shortest Path First (OSPF) virtual link, use the authentication command. To remove the authentication type for a virtual link, use the no form of this command.
authentication [ key-chain key-name | message-digest | null ]
Syntax Description
Command Default
Defaults to password authentication if you configure authentication with none of the optional keywords.
Command Modes
Command History
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Usage Guidelines
Use the authentication command in virtual link configuration mode to configure the authentication method used on the virtual link. Use the message-diges t keyword to configure MD5 message digest authentication and use the message-digest-key command to complete this authentication configuration. Use the key-chain keyword to configure password authentication using key chains and use the key chain command to complete this authentication configuration. Use the authentication command with no keywords to configure a password for the virtual link, and use the authentication-key command to complete this authentication configuration.
Examples
This example shows how to enable message-digest authentication:
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Assigns a password to be used by neighboring routers that are using the password authentication of OSPF. |
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authentication-key (OSPF virtual link)
To assign a password to be used by an Open Shortest Path First (OSPF) virtual link, use the authentication-key command. To remove a previously assigned OSPF password, use the no form of this command.
authentication-key [ 0 | 3 ] password
Syntax Description
Any continuous string of characters that can be entered from the keyboard up to 8 bytes. |
Command Default
Command Modes
Command History
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Usage Guidelines
Use the authentication-key command to configure the password for password authentication on an OSPF virtual link. All devices on the same virtual link must have the same password to be able to exchange OSPF information.
Examples
This example shows how to enable the authentication key with the string yourpass:
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auto-cost (OSPF)
To control how Open Shortest Path First (OSPF) calculates default metrics for an interface, use the auto-cost command. To assign the default reference bandwidth of 40 Gb/s, use the no form of this command.
auto-cost reference-bandwidth bandwidth [ Gbps | Mbps ]
no auto-cost reference-bandwidth
Syntax Description
Command Default
40 Gb/s. The bandwidth defaults to Gb/s if you do not specify the Gpbs or Mbps keyword.
Command Modes
Command History
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Command History
Usage Guidelines
Use the auto-cost command to set the reference bandwidth used by the OSPF cost-metric calculation.
The value set by the ip ospf cost command overrides the cost that results from the auto-cost command.
Examples
This example shows how to set the reference bandwidth for all local interfaces in an OSPF instance:
Related Commands
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Explicitly specifies the cost of sending a packet on an interface. |
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