Table Of Contents
default-information originate (OSPF)
show ip ospf retransmission-list
OSPF Commands
Use the commands in this chapter to configure and monitor the Open Shortest Path First (OSPF) routing protocol. For OSPF configuration information and examples, refer to the "Configuring OSPF" chapter of the Network Protocols Configuration Guide, Part 1.
area authentication
To enable authentication for an OSPF area, use the area authentication command in router configuration mode. To remove an area's authentication specification or a specified area from the configuration, use the no form of this command.
area area-id authentication [message-digest]
no area area-id authentication
no area area-id
Syntax Description
Defaults
Type 0 authentication (no authentication)
Command Modes
Router configuration
Command History
Usage Guidelines
Specifying authentication for an area sets the authentication to Type 1 (simple password) as specified in RFC 1247. If this command is not included in the configuration file, authentication of Type 0 (no authentication) is assumed.
The authentication type must be the same for all routers and access servers in an area. The authentication password for all OSPF routers on a network must be the same if they are to communicate with each other via OSPF. Use the ip ospf authentication command 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.
To remove the area's authentication specification, use the no form of this command with the authentication keyword.
Note
To remove the specified area from the software configuration, use the command no area area-id (with no other keywords). That is, no area area-id removes all area options, such as area authentication, area default-cost, area nssa, area range, area stub, and area virtual-link.
Examples
The following example mandates authentication for areas 0 and10.0.0.0 of OSPF routing process 201. Authentication keys are also provided.
interface ethernet 0ip address 192.168.251.201 255.255.255.0ip ospf authentication-key adcdefgh!interface ethernet 1ip address 10.56.0.201 255.255.0.0ip ospf authentication-key ijklmnop!router ospf 201network 10.0.0.0 0.255.255.255 area 10.0.0.0network 192.168.0.0 0.0.255.255 area 0area 10.0.0.0 authenticationarea 0 authenticationRelated Commands
area default-cost
To specify a cost for the default summary route sent into a stub area, use the area default-cost command in router configuration mode. 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
Defaults
cost: 1
Command Modes
Router configuration
Command History
Usage Guidelines
The command is used only on an area border router attached to a stub area.
There are two stub area router configuration commands: the stub and default-cost options of the area command. In all routers and access servers attached to the stub area, the area should be configured as a stub area using the stub option of the area command. Use the default-cost option only on an area border router attached to the stub area. The default-cost option provides the metric for the summary default route generated by the area border router into the stub area.
Note
Examples
The following example assigns a default-cost of 20 to stub network 10.10.0.0.0:
interface ethernet 0ip address 10.56.0.201 255.255.0.0!router ospf 201network 10.0.0.0 0.255.255.255 area 10.0.0.0area 10.0.0.0 stubarea 10.0.0.0 default-cost 20Related Commands
area nssa
To configure an area as a not so stubby area (NSSA), use the area nssa command in router configuration mode. To remove the nssa distinction from the area, use the no form of this command.
area area-id nssa [no-redistribution] [default-information-originate [metric] [metric-type]] [no-summary]
no area area-id nssa
no area area-id
Syntax Description
Defaults
No NSSA area is defined.
Command Modes
Router configuration
Command History
Usage Guidelines
Note
Examples
The following example enables NSSA authentication on area 1:
router ospf1redistribute rip subnetsnetwork 172.19.92.0.0.0.0.255 area 1area 1 nssaarea range
To consolidate and summarize routes at an area boundary, use the area range command in router configuration mode. To disable this function, use the no form of this command.
area area-id range address mask [advertise | not-advertise]
no area area-id range address mask
no area area-id
Syntax Description
Defaults
This command is disabled by default.
Command Modes
Router configuration
Command History
Usage Guidelines
The area range command is used only with area border routers (ABRs). It is used to consolidate or summarize routes for an area. The result is that a single summary route is advertised to other areas by the ABR. Routing information is condensed at area boundaries. External to the area, a single route is advertised for each address range. This behavior is called route summarization.
Multiple area router configuration commands specifying the range option can be configured. Thus, OSPF can summarize addresses for many different sets of address ranges.
Note
Examples
The following example specifies one summary route to be advertised by the ABR to other areas for all subnets on network 10.0.0.0 and for all hosts on network 192.168.110.0:
interface ethernet 0ip address 192.168.110.201 255.255.255.0!interface ethernet 1ip address 10.56.0.201 255.255.0.0!router ospf 201network 10.0.0.0 0.255.255.255 area 10.0.0.0network 192.168.110.0 0.0.0.255 area 0area 10.0.0.0 range 10.0.0.0 255.0.0.0area 0 range 192.168.110.0 255.255.255.0area stub
To define an area as a stub area, use the area stub command in router configuration mode. To disable this function, use the no form of this command.
area area-id stub [no-summary]
no area area-id stub
no area area-id
Syntax Description
area-id
Identifier for the stub area; either a decimal value or an IP address.
no-summary
(Optional) Prevents an ABR from sending summary link advertisements into the stub area.
Defaults
No stub area is defined.
Command Modes
Router configuration
Command History
Usage Guidelines
You must configure the area stub command on all routers and access servers in the stub area. Use the area router configuration command with the default-cost option to specify the cost of a default internal router sent into a stub area by an area border router.
There are two stub area router configuration commands: the stub and default-cost options of the area router configuration command. In all routers attached to the stub area, the area should be configured as a stub area using the stub option of the area command. Use the default-cost option only on an ABR attached to the stub area. The default-cost option provides the metric for the summary default route generated by the area border router into the stub area.
To further reduce the number of link state advertisements (LSAs) sent into a stub area, you can configure no-summary on the ABR to prevent it from sending summary LSAs (LSA type 3) into the stub area.
Note
Examples
The following example assigns a default cost of 20 to stub network 10.0.0.0:
interface ethernet 0ip address 10.56.0.201 255.255.0.0!router ospf 201network 10.0.0.0 0.255.255.255 area 10.0.0.0area 10.0.0.0 stubarea 10.0.0.0 default-cost 20Related Commands
Enables authentication for an OSPF area.
Specifies a cost for the default summary route sent into a stub area.
area virtual-link
To define an OSPF virtual link, use the area virtual-link command in router configuration mode with the optional parameters. To remove a virtual link, use the no form of this command.
area area-id virtual-link router-id [authentication [message-digest | null]] [hello-interval seconds] [retransmit-interval seconds] [transmit-delay seconds] [dead-interval seconds] [[authentication-key key] | [message-digest-key keyid md5 key]]
no area area-id virtual-link router-id [authentication [message-digest | null]] [hello-interval seconds] [retransmit-interval seconds] [transmit-delay seconds] [dead-interval seconds] [[authentication-key key] | [message-digest-key keyid md5 key]]
no area area-id
Syntax Description
Defaults
area-id: No area ID is predefined.
router-id: No router ID is predefined.
hello-interval seconds: 10 seconds
retransmit-interval seconds: 5 seconds
transmit-delay seconds: 1 second
dead-interval seconds: 40 seconds
authentication-key key: No key is predefined.
message-digest-key key-id md5 key: No key is predefined.
Command Modes
Router configuration
Command History
10.0
This command was introduced.
11.0
The following keywords and arguments were added:
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Usage Guidelines
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.
The smaller the hello interval, the faster topological changes will be detected, but more routing traffic will ensue.
The setting of the retransmit interval should be conservative, or needless retransmissions will result. The value should be larger for serial lines and virtual links.
The transmit delay value should take into account the transmission and propagation delays for the interface.
The Cisco IOS software will use the specified authentication key only when authentication is enabled for the backbone with the area area-id authentication router configuration command.
The two authentication schemes, simple text and MD5 authentication, are mutually exclusive. You can specify one or the other or neither. Any keywords and arguments you specify after authentication-key key or message-digest-key key-id md5 key are ignored. Therefore, specify any optional arguments before such a keyword-argument combination.
Note
Note
Examples
The following example establishes a virtual link with default values for all optional parameters:
router ospf 201network 10.0.0.0 0.255.255.255 area 10.0.0.0area 10.0.0.0 virtual-link 10.3.4.5The following example establishes a virtual link with MD5 authentication:
router ospf 201network 10.0.0.0 0.255.255.255 area 10.0.0.0area 10.0.0.0 virtual-link 10.3.4.5 message-digest-key 3 md5 sa5721bk47Related Commands
Enables authentication for an OSPF area.
service password-encryption
Encrypts passwords.
Displays general information about OSPF routing processes.
auto-cost
To control how OSPF calculates default metrics for the interface, use the auto-cost command in router configuration mode. To assign cost based only on the interface type, use the no form of this command.
auto-cost reference-bandwidth ref-bw
no auto-cost reference-bandwidth
Syntax Description
reference-bandwidth ref-bw
Rate in megabits per second (bandwidth). The range is 1 to 4294967; the default is 100.
Defaults
100 megabits per second
Command Modes
Router configuration
Command History
Usage Guidelines
In Cisco IOS Release 10.3 and later, by default OSPF will calculate the OSPF metric for an interface according to the bandwidth of the interface. For example, a 64K link will get a metric of 1562, and a T1 link will have a metric of 64.
The OSPF metric is calculated as ref-bw divided by bandwidth, with ref-bw equal to 108 by default, and bandwidth determined by the bandwidth command. The calculation gives FDDI a metric of 1.
If you have multiple links with high bandwidth (such as FDDI or ATM), you might want to use a larger number to differentiate the cost on those links.
The value set by the ip ospf cost command overrides the cost resulting from the auto-cost command.
Examples
The following example changes the cost of the FDDI link to 10, while the gigabit Ethernet link remains at a cost of 1. Thus, the link costs are differentiated.
router ospf 1auto-cost reference-bandwidth 1000Related Commands
clear ip ospf
To clear redistribution based on the OSPF routing process ID, use the clear ip ospf command in privileged EXEC mode.
clear ip ospf [pid] {process | redistribution | counters [neighbor [intf] [nbr-id]]}
Syntax Description
Command Modes
Privileged EXEC
Command History
Usage Guidelines
Use the pid option to clear only one OSPF process. If the pid option is not specified, all OSPF processes are cleared.
Examples
The following example clears all OSPF processes:
clear ip ospf process!compatible rfc1583
To restore the method used to calculate summary route costs per RFC 1583, use the compatible rfc1583 command in router configuration mode. To disable RFC 1583 compatibility, use the no form of this command.
compatible rfc1583
no compatible rfc1583
Syntax Description
This command has no arguments or keywords.
Defaults
Compatible with RFC 1583.
Command Modes
Router configuration
Command History
Usage Guidelines
To minimize the chance of routing loops, all OSPF routers in an OSPF routing domain should have RFC compatibility set identically.
Because of the introduction of RFC 2328, OSPF Version 2, the method used to calculate summary route costs has changed. Use the no compatible rfc1583 command to enable the calculation method used per RFC 2328.
Examples
The following example specifies that the router process is compatible with RFC 1583:
router ospf 1 compatible rfc1583!default-information originate (OSPF)
To generate a default route into an OSPF routing domain, use the default-information originate command in router configuration mode. To disable this feature, use the no form of this command.
default-information originate [always] [metric metric-value] [metric-type type-value]
{level-1 | level-1-2 | level-2} [route-map map-name]no default-information originate [always] [metric metric-value] [metric-type type-value]
{level-1 | level-1-2 | level-2} [route-map map-name]Syntax Description
Defaults
This command is disabled by default.
Command Modes
Router configuration
Command History
Usage Guidelines
Whenever you use the redistribute or the default-information router configuration command to redistribute routes into an OSPF routing domain, the Cisco IOS software automatically becomes an autonomous system boundary router (ASBR). However, an ASBR does not, by default, generate a default route into the OSPF routing domain. The software still must have a default route for itself before it generates one, except when you have specified the always keyword.
When you use this command for the OSPF process, the default network must reside in the routing table and you must satisfy the route-map map-name keyword. Use the default-information originate always route-map map-name form of the command when you do not want the dependency on the default network in the routing table.
Examples
The following example specifies a metric of 100 for the default route redistributed into the OSPF routing domain and an external metric type of Type 1:
router ospf 109redistribute igrp 108 metric 100 subnetsdefault-information originate metric 100 metric-type 1Related Commands
redistribute (IP)
Redistributes routes from one routing domain into another routing domain.
default-metric (OSPF)
To set default metric values for the OSPF routing protocol, use this form of the default-metric command in router configuration mode. To return to the default state, use the no form of this command.
default-metric number
no default-metric number
Syntax Description
Defaults
Built-in, automatic metric translations, as appropriate for each routing protocol. The metric of redistributed connected and static routes is set to 0.
Command Modes
Router configuration
Command History
Usage Guidelines
The default-metric command is used in conjunction with the redistribute router configuration command to cause the current routing protocol to use the same metric value for all redistributed routes. A default metric helps solve the problem of redistributing routes with incompatible metrics. Whenever metrics do not convert, using a default metric provides a reasonable substitute and enables the redistribution to proceed.
Note
Examples
The following example shows a router in autonomous system 109 using both the RIP and the OSPF routing protocols. The example advertises OSPF-derived routes using the RIP protocol and assigns the IGRP-derived routes a RIP metric of 10.
router ripdefault-metric 10redistribute ospf 109Related Commands
redistribute (IP)
Redistributes routes from one routing domain into another routing domain.
distance ospf
To define OSPF route administrative distances based on route type, use the distance ospf command in router configuration mode. To restore the default value, use the no form of this command.
distance ospf {[intra-area dist1] [inter-area dist2] [external dist3]}
no distance ospf
Syntax Description
Defaults
dist1: 110
dist2: 110
dist3: 110
Command Modes
Router configuration
Command History
Usage Guidelines
You must specify at least one of the keyword/argument pairs.
This command performs the same function as the distance command used with an access list. However, the distance ospf command allows you to set a distance for an entire group of routes, rather than a specific route that passes an access list.
A common reason to use the distance ospf command is when you have multiple OSPF processes with mutual redistribution, and you want to prefer internal routes from one over external routes from the other.
Examples
The following example changes the external distance to 200, making the route less reliable.
Router A
router ospf 1redistribute ospf 2 subnetdistance ospf external 200!router ospf 2redistribute ospf 1 subnetdistance ospf external 200Router B
router ospf 1 redistribute ospf 2 subnetdistance ospf external 200 ! router ospf 2redistribute ospf 1 subnetdistance ospf external 200Related Commands
ip ospf authentication
To specify the authentication type for an interface, use the ip ospf authentication command in interface configuration mode. To remove the authentication type for an interface, use the no form of this command.
ip ospf authentication [message-digest | null]
no ip ospf authentication
Syntax Description
Defaults
The area default is no authentication (null authentication).
Command Modes
Interface configuration
Command History
Usage Guidelines
Before using the ip ospf authentication command, configure a password for the interface using the ip ospf authentication-key command. If you use the ip ospf authentication message-digest command, configure the message-digest key for the interface with the ip ospf message-digest-key command.
For backward compatibility, authentication type for an area is still supported. If the authentication type is not specified for an interface, the authentication type for the area will be used (the area default is null authentication).
Examples
The following example enables message digest authentication:
ip ospf authentication message-digestRelated Commands
ip ospf authentication-key
To assign a password to be used by neighboring routers that are using OSPF's simple password authentication, use the ip ospf authentication-key command in interface configuration mode. To remove a previously assigned OSPF password, use the no form of this command.
ip ospf authentication-key password
no ip ospf authentication-key
Syntax Description
password
Any continuous string of characters that can be entered from the keyboard up to 8 bytes in length.
Defaults
No password is specified.
Command Modes
Interface configuration
Command History
Usage Guidelines
The password created by this command is used as a "key" that is inserted directly into the OSPF header when the Cisco IOS software originates routing protocol packets. A separate password can be assigned to each network on a per-interface basis. All neighboring routers on the same network must have the same password to be able to exchange OSPF information.
Note
Examples
The following example enables the authentication key with the string yourpass:
ip ospf authentication-key yourpassRelated Commands
ip ospf cost
To explicitly specify the cost of sending a packet on an interface, use the ip ospf cost command in interface configuration mode. To reset the path cost to the default value, use the no form of this command.
ip ospf cost cost
no ip ospf cost
Syntax Description
cost
Unsigned integer value expressed as the link state metric. It can be a value in the range 1 to 65535.
Defaults
No default cost is predefined.
Command Modes
Interface configuration
Command History
Usage Guidelines
You can set the metric manually using this command, if you need to change the default. Using the bandwidth command changes the link cost as long as this command is not used.
The link state metric is advertised as the link cost in the router link advertisement. We do not support type of service (TOS), so you can assign only one cost per interface.
In general, the path cost is calculated using the following formula:
108 รท Bandwidth
Using this formula, the default path costs were calculated as noted in the following list. If these values do not suit your network, you can use your own method of calculating path costs.
•
•
•
•
•
•
•
•
Examples
The following example sets the interface cost value to 65:
ip ospf cost 65ip ospf database-filter
To filter outgoing LSAs to an OSPF interface, use the ip ospf database-filter command in interface configuration mode. To restore the forwarding of LSAs to the interface, use the no form of this command.
ip ospf database-filter all out
no ip ospf database-filter all out
Syntax Description
This command has no arguments or keywords.
Defaults
This command is disabled by default. All outgoing LSAs are flooded to the interface.
Command Modes
Interface configuration
Command History
Usage Guidelines
This command performs the same function that the neighbor database-filter command performs on a neighbor basis.
Examples
The following example prevents flooding of OSPF LSAs to broadcast, nonbroadcast, or point-to-point networks reachable through Ethernet interface 0:
interface ethernet 0ip ospf database-filter all outRelated Commands
ip ospf dead-interval
To set how long hello packets must not have been seen before its neighbors declare the router down, use the ip ospf dead-interval command in interface configuration mode. To return to the default time, use the no form of this command.
ip ospf dead-interval seconds
no ip ospf dead-interval
Syntax Description
seconds
Unsigned integer that specifies the interval in seconds; the value must be the same for all nodes on the network.
Defaults
Four times the interval set by the ip ospf hello-interval command
Command Modes
Interface configuration
Command History
Usage Guidelines
The interval is advertised in the router's hello packets. This value must be the same for all routers and access servers on a specific network.
Examples
The following example sets the OSPF dead interval to 60 seconds:
interface ethernet 1ip ospf dead-interval 60Related Commands
Specifies the interval between hello packets that the Cisco IOS software sends on the interface.
ip ospf demand-circuit
To configure OSPF to treat the interface as an OSPF demand circuit, use the ip ospf demand-circuit command in interface configuration mode. To remove the demand circuit designation from the interface, use the no form of this command.
ip ospf demand-circuit
no ip ospf demand-circuit
Syntax Description
This command has no arguments or keywords.
Defaults
The circuit is not a demand circuit.
Command Modes
Interface configuration
Command History
Usage Guidelines
On point-to-point interfaces, only one end of the demand circuit must be configured with this command. Periodic hellos are suppressed and periodic refreshes of LSAs do not flood the demand circuit. It allows the underlying datalink layer to be closed when the topology is stable. In point-to-multipoint topology, only the multipoint end must configured with this command.
Examples
The following example sets the configures an ISDN on demand circuit:
router ospf1
