- Cisco IOS IP Command Reference, Volume 2 of 3: Routing Protocols, Release 12.2
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Table Of Contents
default-information originate (OSPF)
ip ospf database-filter all out
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 Cisco IOS IP Configuration Guide.
area authentication
To enable authentication for an OSPF area, use the area authentication command in router configuration mode. To remove an authentication specification of an area 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 [message-digest]
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-key interface 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 interface command.
To remove the authentication specification for an area, use the no form of this command with the authentication keyword.
Note
To remove the specified area from the software configuration, use the no area area-id command (with no other keywords). That is, the no area area-id command 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 and 10.0.0.0 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 or not so stubby area (NSSA), 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 (ABR) attached to a stub or NSSA.
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 ABR attached to the stub area. The default-cost option provides the metric for the summary default route generated by the ABR 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
area filter-list
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 prefix {prefix-list-name in | out}
no area {area-id} filter-list prefix {prefix-list-name in | out}
Syntax Description
Defaults
This command has no default behavior.
Command Modes
Router configuration
Command History
Usage Guidelines
With this feature enabled in the "in" direction, all type 3 LSAs originated by the ABR to this area, based on information from all other areas, are filtered by the prefix list. Type 3 LSAs that were originated as a result of the area-range command in another area are treated like any other type 3 LSA that was originated individually. Any prefix that does not match an entry in the prefix list is implicitly denied.
With this feature enabled in the "out" direction, all type 3 LSAs advertised by the ABR, based on information from this area to all other areas, are filtered by the prefix list. If the area-range command has been configured for this area, type 3 LSAs that correspond to the area range are sent to all other areas, only if there is at least one prefix in the area range that matches an entry in the prefix list.
If all specific prefixes are denied by the prefix list, type 3 LSAs that correspond to the area-range command will not be sent to any other area. Prefixes that are not permitted by the prefix list are implicitly denied.
Examples
The following example filters prefixes that are sent from all other areas to area 1:
area 1 filter-list prefix-list AREA_1 inarea 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-redistribution] [default-information-originate [metric] [metric-type]] [no-summary]
Syntax Description
Defaults
No NSSA area is defined.
Command Modes
Router configuration
Command History
Usage Guidelines
To remove the specified area from the software configuration, use the no area area-id command (with no other keywords). That is, the no area area-id command 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 makes area 1 an NSSA area:
router ospf 1redistribute 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 ip-address mask [advertise | not-advertise] [cost cost]
no area area-id range ip-address mask [advertise | not-advertise] [cost cost]
Syntax Description
Defaults
This command is disabled by default.
Command Modes
Router configuration
Command History
10.0
This command was introduced.
12.2
The cost cost keyword and argument were added.
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 192.168.120.201 255.255.255.0!router ospf 201network 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 192.168.110.0 255.255.0.0 cost 60Related Commands
area 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-summary]
Syntax Description
area-id
Identifier for the stub area; either a decimal value or an IP address.
no-summary
(Optional) Prevents an Area Border Router (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 ABR.
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 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 (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 key-id 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 key-id 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
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.
For Cisco IOS Release 12.2 and later releases, authentication type now is specified on a per-interface basis, rather than on a per-area basis, per RFC 2178. For backward compatability, authentication type for an area is still supported. If the authentication type is not specified for an interface, the interface will use the authentication type that was specified for the area. If no authentication type has been specified for the area, the area default is null authentication.
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 Mbps (bandwidth). The range is from 1 to 4294967; the default is 100.
Defaults
100 Mbps
Command Modes
Router configuration
Command History
Usage Guidelines
In Cisco IOS Release 10.3 and later releases, 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 the ref-bw value divided by the 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 [neighbor-interface] [neighbor-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 processcompatible 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
This command is backward compatible with Cisco IOS Release 12.0.
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 external 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] [route-map map-name]
no default-information originate [always] [metric metric-value] [metric-type type-value] [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 and argument. 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.
Notes:
•
For example, the following command works:
ip prefix-list anyrtcondition seq 5 permit 0.0.0.0/0However, the following command is not supported:
ip prefix-list anyrtcondition seq 5 permit 0.0.0.0/0 le 32•
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 the default-metric command in router configuration mode. To return to the default state, use the no form of this command.
default-metric metric-value
no default-metric metric-value
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 Routing Information Protocol (RIP) and the OSPF routing protocols. The example advertises OSPF-derived routes using RIP and assigns the Internal Gateway Routing Protocol (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.
discard-route
To reinstall either an external or internal discard route that was previously removed, use the discard-route command in router configuration mode. To remove either an external or internal discard route, use the no form of this command.
discard-route [external | internal]
no discard-route [external | internal]
Syntax Description
Defaults
External and internal discard route entries are installed.
Command Modes
Router configuration
Command History
Usage Guidelines
External and internal discard route entries are installed in routing tables by default. During route summarization, routing loops may occur when data is sent to a nonexisting network that appears to be a part of the summary, and the router performing the summarization has a less specific route (pointing back to the sending router) for this network in its routing table. To prevent the routing loop, a discard route entry is installed in the routing table of the ABR or ASBR.
If for any reason you do not want to use the external or internal discard route, remove the discard route by entering the no discard-route command with either the external or internal keyword.
Examples
The following display shows the discard route functionality installed by default. When external or internal routes are summarized, a summary route to Null0 will appear in the router output from the show ip route command. See the router output lines that appear in bold font:
Router# show ip routeCodes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGPD - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter areaN1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGPi - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2ia - IS-IS inter area, * - candidate default, U - per-user static routeo - ODR, P - periodic downloaded static routeGateway of last resort is not set172.16.0.0/24 is variably subnetted, 3 subnets, 2 masksC 172.16.0.128/25 is directly connected, Loopback1O 172.16.0.0/24 is a summary, 00:00:14, Null0C 172.16.0.0/25 is directly connected, Loopback0172.31.0.0/24 is variably subnetted, 3 subnets, 2 masksC 172.31.0.128/25 is directly connected, Loopback3O 172.31.0.0/24 is a summary, 00:00:02, Null0C 172.31.0.0/25 is directly connected, Loopback2C 192.168.0.0/24 is directly connected, Ethernet0/0RouterB# show ip route ospf172.16.0.0/24 is variably subnetted, 3 subnets, 2 masksO 172.16.0.0/24 is a summary, 00:00:29, Null0172.16.0.0/24 is variably subnetted, 3 subnets, 2 masksO 201.0.0.0/24 is a summary, 00:00:17, Null0When the no discard-route command with the internal keyword is entered, notice the following route change, indicated by the router output lines that appear in bold font:
RouterB# configure terminalEnter configuration commands, one per line. End with CNTL/Z.RouterB(config)# router ospf 1RouterB(config-router)# no discard-route internalRouterB(config-router)#endRouterB# show ip route ospf172.31.0.0/24 is variably subnetted, 3 subnets, 2 masksO 172.16.0.0/24 is a summary, 00:04:14, Null0Next, the no discard-route command with the external keyword is entered to remove the external discard route entry:
RouterB# configure terminalEnter configuration commands, one per line. End with CNTL/Z.RouterB(config)# router ospf 1RouterB(config-router)# no discard-route externalRouterB(config-router)# endThe following router output from the show running-config command confirms that both the external and internal discard routes have been removed from the routing table of RouterB. See the router output lines that appear in bold font:
RouterB# show running-configBuilding configuration...Current configuration : 1114 bytes!version 12.2service timestamps debug uptimeservice timestamps log uptimeno service password-encryption!hostname RouterB...router ospf 1log-adjacency-changesno discard-route externalno discard-route internalarea 1 range 172.16.0.0 255.255.255.0summary-address 172.31.0.0 255.255.255.0redistribute rip subnetsnetwork 192.168.0.0 0.0.0.255 area 0network 172.16.0.0 0.0.0.255 area 1!Related Commands
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 Configuration
router ospf 1redistribute ospf 2 subnetdistance ospf external 200!router ospf 2redistribute ospf 1 subnetdistance ospf external 200Router B Configuration
router ospf 1 redistribute ospf 2 subnetdistance ospf external 200 ! router ospf 2redistribute ospf 1 subnetdistance ospf external 200Related Commands
domain-tag
To set the Open Shortest Path First (OSPF) domain tag value for Type-5 or Type-7 link-state advertisements (LSAs) when OSPF is used as a protocol between a provider edge (PE) router and customer edge (CE) router, use the domain-tag command in router configuration mode. To reinstate the default tag value, use the no form of this command.
domain-tag tag-value
no domain-tag tag-value
Syntax Description
Defaults
The default value is calculated based on the BGP autonomous system number of the MPLS VPN backbone. The four highest bits are set to 1101 according to RFC 1745. The lowest 16 bits map the BGP autonomous system number of the MPLS VPN backbone.
Command Modes
Router configuration
Command History
Usage Guidelines
When OSPF is used between a PE router and a CE router, BGP routes that come from the MPLS backbone are redistributed to OSPF. These redistributed routes can be announced in Type-3, Type-5, or Type-7 LSAs. If the redistribution of the BGP routes results in Type-5 or Type-7 LSAs, the External Route Tag will be set to the value of the tag. If another PE router receives a Type-5 or Type-7 LSA with an External Route Tag equal to the set tag value, it will ignore the LSA, therefore preventing the redistributed routes that originated from the MPLS backbone from returning via some other location on the MPLS backbone.
Examples
The following example configures the tag value 777:
Router(config)# router ospf 10 vrf grcRouter(config-router)# domain-tag 777The show ip ospf database command is entered to verify that the tag value 777 has been applied to the External Route Tag:
Router# show ospf database external 192.168.50.1OSPF Router with ID (192.168.239.66) (Process ID 10)Type-5 AS External Link StatesLS age: 18Options: (No TOS-capability, DC)S Type: AS External LinkLink State ID: 192.168.238.1 (External Network Number )Advertising Router: 192.168.239.66LS Seq Number: 80000002Checksum: 0xDAB0Length: 36Network Mask: /32Metric Type: 2 (Larger than any link state path)TOS: 0Metric: 1Forward Address: 0.0.0.0External Route Tag: 777...OSPF Router with ID (198.168.237.56) (Process ID 1)Related Commands
show ospf database
Displays lists of information related to the OSPF database for a specific router.
ignore lsa mospf
To suppress the sending of syslog messages when the router receives link-state advertisement (LSA) Type 6 Multicast OSPF (MOSPF) packets, which are unsupported, use the ignore lsa mospf command in router configuration mode. To restore the sending of syslog messages, use the no form of this command.
ignore lsa mospf
no ignore lsa mospf
Syntax Description
This command has no arguments or keywords.
Defaults
This command is disabled by default. Each MOSPF packet causes the router to send a syslog message.
Command Modes
Router configuration
Command History
Usage Guidelines
Cisco routers do not support LSA Type 6 MOSPF packets, and they generate syslog messages if they receive such packets. If the router is receiving many MOSPF packets, you might want to configure the router to ignore the packets and thus prevent a large number of syslog messages.
Examples
The following example configures the router to suppress the sending of syslog messages when it receives MOSPF packets:
router ospf 109ignore lsa mospfip 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 the OSPF 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
Enables authentication for an OSPF area.
Specifies authentication type for an interface.
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 interface-cost
no ip ospf cost interface-cost
Syntax Description
interface-cost
Unsigned integer value expressed as the link-state metric. It can be a value in the range from 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 / 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 all out
To filter outgoing link-state advertisements (LSAs) to an OSPF interface, use the ip ospf database-filter all out 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 the interval at which hello packets must not be seen before 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
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 router 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 hello messages are suppressed and periodic refreshes of link-state advertisements (LSAs) do not flood the demand circuit. This command allows the underlying data link 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 configuration for an ISDN on-demand circuit:
router ospf 1network 10.0.3.0 255.255.255.0 area 0interface BRI0ip ospf demand-circuitip ospf flood-reduction
To suppress the unnecessary flooding of link-state advertisements (LSAs) in stable topologies, use the ip ospf flood-reduction command in interface configuration mode. To disable this feature, use the no form of this command.
ip ospf flood-reduction
no ip ospf flood-reduction
Syntax Description
This command has no arguments or keywords.
Defaults
This command is disabled by default.
Command Modes
Interface configuration
Command History
Usage Guidelines
All routers supporting the OSPF demand circuit are compatible and can interact with routers supporting flooding reduction.
Examples
The following example reduces the flooding of unnecessary LSAs on serial interface 0:
interface serial 0ip ospf flood-reductionRelated Commands
Displays OSPF-related interface information.
Displays OSPF-neighbor information on a per-interface basis.
ip ospf hello-interval
To specify the interval between hello packets that the Cisco IOS software sends on the interface, use the ip ospf hello-interval command in interface configuration mode. To return to the default time, use the no form of this command.
ip ospf hello-interval seconds
no ip ospf hello-interval
Syntax Description
seconds
Specifies the interval (in seconds). The value must be the same for all nodes on a specific network.
Defaults
10 seconds (Ethernet)
30 seconds (nonbroadcast)
Command Modes
Interface configuration
Command History
Usage Guidelines
This value is advertised in the hello packets. The smaller the hello interval, the faster topological changes will be detected, but more routing traffic will ensue. This value must be the same for all routers and access servers on a specific network.
Examples
The following example sets the interval between hello packets to 15 seconds:
interface ethernet 1ip ospf hello-interval 15Related Commands
Sets the time period for which hello packets must not have been seen before neighbors declare the router down.
ip ospf message-digest-key
To enable OSPF Message Digest 5 (MD5) authentication, use the ip ospf message-digest-key command in interface configuration mode. To remove an old MD5 key, use the no form of this command.
ip ospf message-digest-key key-id md5 key
no ip ospf message-digest-key key-id
Syntax Description
Defaults
OSPF MD5 authentication is disabled.
Command Modes
Interface configuration
Command History
Usage Guidelines
Usually, one key per interface is used to generate authentication information when sending packets and to authenticate incoming packets. The same key identifier on the neighbor router must have the same key value.
The process of changing keys is as follows. Suppose the current configuration is as follows:
interface ethernet 1ip ospf message-digest-key 100 md5 OLDYou change the configuration to the following:
interface ethernet 1ip ospf message-digest-key 101 md5 NEWThe system assumes its neighbors do not have the new key yet, so it begins a rollover process. It sends multiple copies of the same packet, each authenticated by different keys. In this example, the system sends out two copies of the same packet—the first one authenticated by key 100 and the second one authenticated by key 101.
Rollover allows neighboring routers to continue communication while the network administrator is updating them with the new key. Rollover stops once the local system finds that all its neighbors know the new key. The system detects that a neighbor has the new key when it receives packets from the neighbor authenticated by the new key.
After all neighbors have been updated with the new key, the old key should be removed. In this example, you would enter the following:
interface ethernet 1no ip ospf message-digest-key 100Then, only key 101 is used for authentication on Ethernet interface 1.
We recommend that you not keep more than one key per interface. Every time you add a new key, you should remove the old key to prevent the local system from continuing to communicate with a hostile system that knows the old key. Removing the old key also reduces overhead during rollover.
Note
Examples
The following example sets a new key 19 with the password 8ry4222:
interface ethernet 1ip ospf message-digest-key 10 md5 xvv560qleip ospf message-digest-key 19 md5 8ry4222Related Commands
Enables authentication for an OSPF area.
Specifies authentication type for an interface.
service password-encryption
Encrypts a password.
ip ospf mtu-ignore
To disable OSPF MTU mismatch detection on receiving DBD packets, use the ip ospf mtu-ignore command in interface configuration mode. To reset to default, use the no form of this command.
ip ospf mtu-ignore
no ip ospf mtu-ignore
Syntax Description
This command has no keywords or arguments.
Defaults
OSPF MTU mismatch detection is enabled.
Command Modes
Interface configuration
Command History
Usage Guidelines
OSPF checks whether neighbors are using the same MTU on a common interface. This check is performed when neighbors exchange Database Descriptor (DBD) packets. If the receiving MTU in the DBD packet is higher than the IP MTU configured on the incoming interface, OSPF adjacency will not be established.
Examples
The following example disables MTU mismatch detection on receiving DBD packets:
interface serial 0/0ip ospf mtu-ignoreip ospf name-lookup
To configure OSPF to look up Domain Name System (DNS) names for use in all OSPF show EXEC command displays, use the ip ospf name-lookup command in global configuration mode. To disable this function, use the no form of this command.
ip ospf name-lookup
no ip ospf name-lookup
Syntax Description
This command has no arguments or keywords.
Defaults
This command is disabled by default.
Command Modes
Global configuration
Command History
Usage Guidelines
This command makes it easier to identify a router because the router is displayed by name rather than by its router ID or neighbor ID.
Examples
The following example configures OSPF to look up DNS names for use in all OSPF show EXEC command displays:
ip ospf name-lookupip ospf network
To configure the OSPF network type to a type other than the default for a given medium, use the ip ospf network command in interface configuration mode. To return to the default value, use the no form of this command.
ip ospf network {broadcast | non-broadcast | {point-to-multipoint [non-broadcast] | point-to-point}}
no ip ospf network
Syntax Description
Defaults
Depends on the network type.
Command Modes
Interface configuration
Command History
10.0
This command was introduced.
10.3
The point-to-multipoint keyword was added.
11.3 AA
The non-broadcast keyword used with the point-to-multipoint keyword was added.
Usage Guidelines
Using this feature, you can configure broadcast networks as NBMA networks when, for example, routers in your network do not support multicast addressing. You can also configure nonbroadcast multiaccess networks (such as X.25, Frame Relay, and Switched Multimegabit Data Service (SMDS)) as broadcast networks. This feature saves you from needing to configure neighbors.
Configuring NBMA networks as either broadcast or nonbroadcast assumes that there are virtual circuits from every router to every router or fully meshed networks. However, there are other configurations where this assumption is not true. For example, a partially meshed network. In these cases, you can configure the OSPF network type as a point-to-multipoint network. Routing between two routers that are not directly connected will go through the router that has virtual circuits to both routers. You need not configure neighbors when using this feature.
If this command is issued on an interface that does not allow it, this command will be ignored.
OSPF has two features related to point-to-multipoint networks. One feature applies to broadcast networks; the other feature applies to nonbroadcast networks:
•
•
Examples
The following example sets your OSPF network as a broadcast network:
interface serial 0ip address 192.168192.168.77.17 255.255.255.0ip ospf network broadcastencapsulation frame-relayThe following example illustrates a point-to-multipoint network with broadcast:
interface serial 0ip address 10.0.1.1 255.255.255.0encapsulation frame-relayip ospf cost 100ip ospf network point-to-multipointframe-relay map ip 10.0.1.3 202 broadcastframe-relay map ip 10.0.1.4 203 broadcastframe-relay map ip 10.0.1.5 204 broadcastframe-relay local-dlci 200!router ospf 1network 10.0.1.0 0.0.0.255 area 0neighbor 10.0.1.5 cost 5neighbor 10.0.1.4 cost 10Related Commands
ip ospf priority
To set the router priority, which helps determine the designated router for this network, use the ip ospf priority command in interface configuration mode. To return to the default value, use the no form of this command.
ip ospf priority number-value
no ip ospf priority number-value
Syntax Description
Defaults
Priority of 1
Command Modes
Interface configuration
Command History
Usage Guidelines
When two routers attached to a network both attempt to become the designated router, the one with the higher router priority takes precedence. If there is a tie, the router with the higher router ID takes precedence. A router with a router priority set to zero is ineligible to become the designated router or backup designated router. Router priority is configured only for interfaces to multiaccess networks (in other words, not to point-to-point networks).
This priority value is used when you configure OSPF for nonbroadcast networks using the neighbor router configuration command for OSPF.
Examples
The following example sets the router priority value to 4:
interface ethernet 0ip ospf priority 4Related Commands
Configures the OSPF network type to a type other than the default for a given medium.
Configures OSPF routers interconnecting to nonbroadcast networks.
ip ospf retransmit-interval
To specify the time between link-state advertisement (LSA) retransmissions for adjacencies belonging to the interface, use the ip ospf retransmit-interval command in interface configuration mode. To return to the default value, use the no form of this command.
ip ospf retransmit-interval seconds
no ip ospf retransmit-interval
Syntax Description
Defaults
5 seconds
Command Modes
Interface configuration
Command History
Usage Guidelines
When a router sends an LSA to its neighbor, it keeps the LSA until it receives back the acknowledgment message. If the router receives no acknowledgment, it will resend the LSA.
The setting of this parameter should be conservative, or needless retransmission will result. The value should be larger for serial lines and virtual links.
Examples
The following example sets the retransmit interval value to 8 seconds:
interface ethernet 2ip ospf retransmit-interval 8ip ospf transmit-delay
To set the estimated time required to send a link-state update packet on the interface, use the ip ospf transmit-delay command in interface configuration mode. To return to the default value, use the no form of this command.
ip ospf transmit-delay seconds
no ip ospf transmit-delay
Syntax Description
seconds
Time (in seconds) required to send a link-state update. The range is from 1 to 65535 seconds. The default is 1 second.
Defaults
1 second
Command Modes
Interface configuration
Command History
Usage Guidelines
Link-state advertisements (LSAs) in the update packet must have their ages incremented by the amount specified in the seconds argument before transmission. The value assigned should take into account the transmission and propagation delays for the interface.
If the delay is not added before transmission over a link, the time in which the LSA propagates over the link is not considered. This setting has more significance on very low-speed links.
Examples
The following example sets the retransmit delay value to 3 seconds:
interface ethernet 0ip ospf transmit-delay 3log-adjacency-changes
To configure the router to send a syslog message when an OSPF neighbor goes up or down, use the log-adjacency-changes command in router configuration mode. To turn off this function, use the no form of this command.
log-adjacency-changes [detail]
no log-adjacency-changes [detail]
Syntax Description
detail
(Optional) Sends a syslog message for each state change, not just when a neighbor goes up or down.
Defaults
Enabled
Command Modes
Router configuration
Command History
11.2
This command was introduced as "ospf log-adjacency-changes".
12.1
The ospf keyword was omitted and the detail keyword was added.
Usage Guidelines
This command allows you to know about OSPF neighbors going up or down without turning on the debug ip ospf adjacency command. The log-adjacency-changes command provides a higher level view of those changes of the peer relationship with less output. This command is on by default but only up/down (full/down) events are reported, unless the detail keyword is also configured.
Examples
The following example configures the router to send a syslog message when an OSPF neighbor state changes:
log-adjacency-changes detailneighbor (OSPF)
To configure OSPF routers interconnecting to nonbroadcast networks, use the neighbor command in router configuration mode. To remove a configuration, use the no form of this command.
neighbor ip-address [priority number] [poll-interval seconds] [cost number] [database-filter all]
no neighbor ip-address [priority number] [poll-interval seconds] [cost number] [database-filter all]
Syntax Description
Defaults
No configuration is specified.
Command Modes
Router configuration
Command History
Usage Guidelines
X.25 and Frame Relay provide an optional broadcast capability that can be configured in the map to allow OSPF to run as a broadcast network. At the OSPF level you can configure the router as a broadcast network. Refer to the x25 map and frame-relay map commands in the "X.25 Commands" and "Frame Relay Commands" chapters, respectively, in the Cisco IOS Wide-Area Networking Command Reference for more detail.
One neighbor entry must be included in the Cisco IOS software configuration for each known nonbroadcast network neighbor. The neighbor address must be on the primary address of the interface.
If a neighboring router has become inactive (hello packets have not been received for the Router Dead Interval period), it may still be necessary to send hello packets to the dead neighbor. These hello packets will be sent at a reduced rate called Poll Interval.
When the router first starts up, it sends only hello packets to those routers with nonzero priority, that is, routers that are eligible to become designated routers (DRs) and backup designated routers (BDRs). After the DR and BDR are selected, DR and BDR will then start sending hello packets to all neighbors in order to form adjacencies.
Note
Prior to Cisco IOS Release 12.0, the neighbor command applied to NBMA networks only. With Release 12.0, the neighbor command applies to NBMA networks and point-to-multipoint networks. On NBMA networks, the cost keyword is not accepted.
Examples
The following example declares a router at address 192.168.3.4 on a nonbroadcast network, with a priority of 1 and a poll interval of 180 seconds:
router ospfneighbor 192.168.3.4 priority 1 poll-interval 180The following example illustrates a point-to-multipoint network with nonbroadcast:
interface Serial0ip address 10.0.1.1 255.255.255.0ip ospf network point-to-multipoint non-broadcastencapsulation frame-relayno keepaliveframe-relay local-dlci 200frame-relay map ip 10.0.1.3 202frame-relay map ip 10.0.1.4 203frame-relay map ip 10.0.1.5 204no shut!router ospf 1network 10.0.1.0 0.0.0.255 area 0neighbor 10.0.1.3 cost 5neighbor 10.0.1.4 cost 10neighbor 10.0.1.5 cost 15Related Commands
Sets the router priority, which helps determine the designated router for this network.
neighbor database-filter
To filter outgoing link-state advertisements (LSAs) to an OSPF neighbor, use the neighbor database-filter command in router configuration mode. To restore the forwarding of LSAs to the neighbor, use the no form of this command.
neighbor ip-address database-filter all out
no neighbor ip-address database-filter all out
Syntax Description
Defaults
This command is disabled by default. All outgoing LSAs are flooded to the neighbor.
Command Modes
Router configuration
Command History
Usage Guidelines
This command performs the same function that the ip ospf database-filter command performs on an interface basis.
Examples
The following example prevents flooding of OSPF LSAs to point-to-multipoint networks to the neighbor at IP address 10.2.3.4:
router ospf 109neighbor 10.2.3.4 database-filter all outRelated Commands
network area
To define the interfaces on which OSPF runs and to define the area ID for those interfaces, use the network area command in router configuration mode. To disable OSPF routing for interfaces defined with the address wildcard-mask pair, use the no form of this command.
network ip-address wildcard-mask area area-id
no network ip-address wildcard-mask area area-id
Syntax Description
Defaults
This command is disabled by default.
Command Modes
Router configuration
Command History
Usage Guidelines
The ip-address and wildcard-mask arguments together allow you to define one or multiple interfaces to be associated with a specific OSPF area using a single command. Using the wildcard-mask argument allows you to define one or multiple interfaces to be associated with a specific OSPF area using a single command. If you intend to associate areas with IP subnets, you can specify a subnet address as the value of the area-id argument.
For OSPF to operate on the interface, the primary address of the interface must be covered by the network area command. If the network area command covers only the secondary address, it will not enable OSPF over that interface.
The Cisco IOS software sequentially evaluates the ip-address wildcard-mask pair for each interface as follows:
1.
2.
3.
There is no limit to the number of network area commands you can use on the router.
Note
When a more specific OSPF network range is removed, interfaces belonging to that network range will be retained and remain active if and only if a less specific network range exists.
For example, consider the following configuration:
router ospf 1network 205.188.129.16 0.0.0.3 area 20network 205.188.129.40 0.0.0.3 area 20network 205.188.129.44 0.0.0.3 area 20network 205.188.129.96 0.0.0.3 area 20network 205.188.128.0 0.0.127.255 area 20!Enter the following:
no network 205.188.129.40 0.0.0.3 area 20Interfaces falling into the network range 205.188.129.40/0.0.0.3 will still remain active because the superset, 205.188.128.0/0.0.127.255, exists for area 20. A more specific network statement will cause interfaces belonging to that range to be removed from a different area only if a less specific network statement (superset) exists.
Consider a configuration such as the following:
!router ospf 1network 205.188.128.0 0.0.127.255 area 20!If the following network statement is entered:
network 205.188.129.96 0.0.0.3 area 40then interfaces belonging to range 205.188.129.96/0.0.0.3, if any, are removed from area 20 and moved to area 40. Network statements with identical ranges but with different area IDs are considered as area changes. For example, the following network statements will cause interfaces belonging to network range 205.188.129.40/0.0.0.3 to move from area 20 to area 40:
network 205.188.129.40 0.0.0.3 area 20network 205.188.129.40 0.0.0.3 area 40Examples
The following partial example initializes OSPF routing process 109, and defines four OSPF areas: 10.9.50.0, 2, 3, and 0. Areas 10.9.50.0, 2, and 3 mask specific address ranges, and area 0 enables OSPF for all other networks.
interface ethernet 0ip address 10.108.20.1 255.255.255.0router ospf 109network 10.108.20.0 0.0.0.255 area 10.9.50.0network 10.108.0.0 0.0.255.255 area 2network 10.109.10.0 0.0.0.255 area 3network 0.0.0.0 255.255.255.255 area 0Related Commands
router-id
To use a fixed router ID, use the router-id command in router configuration mode. To force OSPF to use the previous OSPF router ID behavior, use the no form of this command.
router-id ip-address
no router-id ip-address
Syntax Description
Defaults
No OSPF routing process is defined.
Command Modes
Router configuration
Command History
Usage Guidelines
You can configure an arbitrary value in the IP address format for each router. However, each router ID must be unique.
If this command is used on an OSPF router process which is already active (has neighbors), the new router-ID is used at the next reload or at a manual OSPF process restart. To manually restart the OSPF process, use the clear ip ospf command.
Examples
The following example specifies a fixed router-id:
router-id 10.1.1.1Related Commands
Clears redistribution based on the OSPF routing process ID.
Configures the OSPF routing process.
router ospf
To configure an Open Shortest Path First (OSPF) routing process, use the router ospf command in global configuration mode. To terminate an OSPF routing process, use the no form of this command.
router ospf process-id [vrf vpn-name]
no router ospf process-id [vrf vpn-name]
Syntax Description
Defaults
No OSPF routing process is defined.
Command Modes
Global configuration
Command History
10.0
This command was introduced.
12.0(7)T
The vrf keyword and vpn-name arguments were added to identify a VPN.
12.0(9)ST
The vrf keyword and vpn-name arguments were added.
Usage Guidelines
You can specify multiple OSPF routing processes in each router.
After you enter the router ospf command, you can enter the maximum number of paths. There can be from 1 to 32 paths.
Examples
The following example configures an OSPF routing process and assign a process number of 109:
router ospf 109This example shows a basic OSPF configuration using the router ospf command to configure OSPF VPN routing and forwarding (VRF) instance processes for the VRFs first, second, and third:
Router> enableRouter# configure terminalRouter(config)# router ospf 12 vrf firstRouter(config)# router ospf 13 vrf secondRouter(config)# router ospf 14 vrf thirdRouter(config)# exitThe following example shows usage of the maximum-paths option:
Router> enableRouter# configure terminalRouter(config)# router ospfRouter(config-router)# maximum-paths?Router(config)# 20Router(config)# exitRelated Commands
network area
Defines the interfaces on which OSPF runs and defines the area ID for those interfaces.
show ip ospf
To display general information about OSPF routing processes, use the show ip ospf command in EXEC mode.
show ip ospf [process-id]
Syntax Description
process-id
(Optional) Process ID. If this argument is included, only information for the specified routing process is included.
Command Modes
EXEC
Command History
Examples
The following is sample output from the show ip ospf command when entered without a specific OSPF process ID:
Router# show ip ospfRouting Process "ospf 201" with ID 192.42.110.200Supports only single TOS(TOS0) routeIt is an area border and autonomous system boundary routerRedistributing External Routes from,igrp 200 with metric mapped to 2, includes subnets in redistributionrip with metric mapped to 2igrp 2 with metric mapped to 100igrp 32 with metric mapped to 1Number of areas in this router is 3Area 192.42.110.0Number of interfaces in this area is 1Area has simple password authenticationSPF algorithm executed 6 timesTable 5 describes the significant fields shown in the display.
show ip ospf border-routers
To display the internal OSPF routing table entries to an Area Border Router (ABR) and Autonomous System Boundary Router (ASBR), use the show ip ospf border-routers command in privileged EXEC mode.
show ip ospf border-routers
Syntax Description
This command has no arguments or keywords.
Command Modes
Privileged EXEC
Command History
Examples
The following is sample output from the show ip ospf border-routers command:
Router# show ip ospf border-routersOSPF Process 109 internal Routing TableCodes: i - Intra-area route, I - Inter-area routei 192.168.97.53 [10] via 172.16.1.53, Serial0, ABR, Area 0.0.0.3, SPF 3i 192.168.103.51 [10] via 192.168.96.51, Serial0, ABR, Area 0.0.0.3, SPF 3I 192.168.103.52 [22] via 192.168.96.51, Serial0, ASBR, Area 0.0.0.3, SPF 3I 192.168.103.52 [22] via 172.16.1.53, Serial0, ASBR, Area 0.0.0.3, SPF 3Table 6 describes the significant fields shown in the display.
show ip ospf database
To display lists of information related to the OSPF database for a specific router, use the show ip ospf database command in EXEC mode. The various forms of this command deliver information about different OSPF link-state advertisements(LSAs).
show ip ospf [process-id [area-id]] database
show ip ospf [process-id [area-id]] database [adv-router [ip-address]]
show ip ospf [process-id [area-id]] database [asbr-summary] [link-state-id]
show ip ospf [process-id [area-id]] database [asbr-summary] [link-state-id] [adv-router
[ip-address]]show ip ospf [process-id [area-id]] database [asbr-summary] [link-state-id] [self-originate]
[link-state-id]show ip ospf [process-id [area-id]] database [database-summary]
show ip ospf [process-id [area-id]] database [external] [link-state-id]
show ip ospf [process-id [area-id]] database [external] [link-state-id] [adv-router [ip-address]]
show ip ospf [process-id [area-id]] database [external] [link-state-id] [self-originate]
[link-state-id]show ip ospf [process-id [area-id]] database [network] [link-state-id]
show ip ospf [process-id [area-id]] database [network] [link-state-id] [adv-router [ip-address]]
show ip ospf [process-id [area-id]] database [network] [link-state-id] [self-originate]
[link-state-id]show ip ospf [process-id [area-id]] database [nssa-external] [link-state-id]
show ip ospf [process-id [area-id]] database [nssa-external] [link-state-id] [adv-router
[ip-address]]show ip ospf [process-id [area-id]] database [nssa-external] [link-state-id] [self-originate]
[link-state-id]show ip ospf [process-id [area-id]] database [opaque-area] [link-state-id]
show ip ospf [process-id [area-id]] database [opaque-area] [link-state-id] [adv-router
[ip-address]]show ip ospf [process-id [area-id]] database [opaque-area] [link-state-id] [self-originate]
[link-state-id]show ip ospf [process-id [area-id]] database [opaque-as] [link-state-id]
show ip ospf [process-id [area-id]] database [opaque-as] [link-state-id] [adv-router
[ip-address]]show ip ospf [process-id [area-id]] database [opaque-as] [link-state-id] [self-originate]
[link-state-id]show ip ospf [process-id [area-id]] database [opaque-link] [link-state-id]
show ip ospf [process-id [area-id]] database [opaque-link] [link-state-id] [adv-router
[ip-address]]show ip ospf [process-id [area-id]] database [opaque-link] [link-state-id] [self-originate]
[link-state-id]show ip ospf [process-id [area-id]] database [router] [link-state-id]
show ip ospf [process-id [area-id]] database [router] [adv-router [ip-address]]
show ip ospf [process-id [area-id]] database [router] [self-originate] [link-state-id]
show ip ospf [process-id [area-id]] database [self-originate] [link-state-id]
show ip ospf [process-id [area-id]] database [summary] [link-state-id]
show ip ospf [process-id [area-id]] database [summary] [link-state-id] [adv-router [ip-address]]
show ip ospf [process-id [area-id]] database [summary] [link-state-id] [self-originate]
[link-state-id]Syntax Description
Command Modes
EXEC
Command History
Examples
The following is sample output from the show ip ospf database command when no arguments or keywords are used:
Router# show ip ospf databaseOSPF Router with ID(192.168.1.11) (Process ID 1)Router Link States(Area 0)Link ID ADV Router Age Seq# Checksum Link count192.168.1.8 192.168.1.8 1381 0x8000010D 0xEF60 2192.168.1.11 192.168.1.11 1460 0x800002FE 0xEB3D 4192.168.1.12 192.168.1.12 2027 0x80000090 0x875D 3192.168.1.27 192.168.1.27 1323 0x800001D6 0x12CC 3Net Link States(Area 0)Link ID ADV Router Age Seq# Checksum172.16.1.27 192.168.1.27 1323 0x8000005B 0xA8EE172.17.1.11 192.168.1.11 1461 0x8000005B 0x7ACType-10 Opaque Link Area Link States (Area 0)Link ID ADV Router Age Seq# Checksum Opaque ID10.0.0.0 192.168.1.11 1461 0x800002C8 0x8483 010.0.0.0 192.168.1.12 2027 0x80000080 0xF858 010.0.0.0 192.168.1.27 1323 0x800001BC 0x919B 010.0.0.1 192.168.1.11 1461 0x8000005E 0x5B43 1Table 7 describes the significant fields shown in the display.
The following is sample output from the show ip ospf database command with the asbr-summary keyword:
Router# show ip ospf database asbr-summaryOSPF Router with id(192.168.239.66) (Process ID 300)Displaying Summary ASB Link States(Area 0.0.0.0)LS age: 1463Options: (No TOS-capability)LS Type: Summary Links(AS Boundary Router)Link State ID: 172.16.245.1 (AS Boundary Router address)Advertising Router: 172.16.241.5LS Seq Number: 80000072Checksum: 0x3548Length: 28Network Mask: 0.0.0.0 TOS: 0 Metric: 1Table 8 describes the significant fields shown in the display.
The following is sample output from the show ip ospf database command with the external keyword:
Router# show ip ospf database externalOSPF Router with id(192.168.239.66) (Autonomous system 300)Displaying AS External Link StatesLS age: 280Options: (No TOS-capability)LS Type: AS External LinkLink State ID: 143.10.0.0 (External Network Number)Advertising Router: 10.187.70.6LS Seq Number: 80000AFDChecksum: 0xC3ALength: 36Network Mask: 255.255.0.0Metric Type: 2 (Larger than any link state path)TOS: 0Metric: 1Forward Address: 0.0.0.0External Route Tag: 0Table 9 describes the significant fields shown in the display.
The following is sample output from the show ip ospf database command with the network keyword:
Router# show ip ospf database networkOSPF Router with id(192.168.239.66) (Process ID 300)Displaying Net Link States(Area 0.0.0.0)LS age: 1367Options: (No TOS-capability)LS Type: Network LinksLink State ID: 10.187.1.3 (address of Designated Router)Advertising Router: 192.168.239.66LS Seq Number: 800000E7Checksum: 0x1229Length: 52Network Mask: 255.255.255.0Attached Router: 192.168.239.66Attached Router: 10.187.241.5Attached Router: 10.187.1.1Attached Router: 10.187.54.5Attached Router: 10.187.1.5Table 10 describes the significant fields shown in the display.
The following is sample output, carrying Multiprotocol Label Switching (MPLS) traffic engineering specification information, from the show ip ospf database command with the opaque-area keyword:
Router# show ip ospf database opaque-area adv-router 192.168.1.12OSPF Router with id(192.168.1.11) (Process ID 1)Type-10 Opaque Link Area Link States (Area 0)LS age: 224Options: (No TOS-capability, DC)LS Type: Opaque Area LinkLink State ID: 1.0.0.0Opaque Type: 1Opaque ID: 0Advertising Router: 192.168.1.12LS Seq Number: 80000081Checksum: 0xF659Length: 132Fragment number : 0MPLS TE router ID : 192.168.1.12Link connected to Point-to-Point networkLink ID : 192.168.1.11Interface Address : 172.16.1.12Neighbor Address : 172.16.1.11Admin Metric : 10Maximum bandwidth : 193000Maximum reservable bandwidth : 125000Number of Priority : 8Priority 0 : 125000 Priority 1 : 125000Priority 2 : 125000 Priority 3 : 125000Priority 4 : 125000 Priority 5 : 125000Priority 6 : 125000 Priority 7 : 100000Affinity Bit : 0x0Number of Links : 1Table 11 describes the significant fields shown in the display.
The following is sample output from the show ip ospf database command with the router keyword:
Router# show ip ospf database routerOSPF Router with id(192.168.239.66) (Process ID 300)Displaying Router Link States(Area 0.0.0.0)LS age: 1176Options: (No TOS-capability)LS Type: Router LinksLink State ID: 10.187.21.6Advertising Router: 10.187.21.6LS Seq Number: 80002CF6Checksum: 0x73B7Length: 120AS Boundary Router155 Number of Links: 8Link connected to: another Router (point-to-point)(link ID) Neighboring Router ID: 10.187.21.5(Link Data) Router Interface address: 10.187.21.6Number of TOS metrics: 0TOS 0 Metrics: 2Table 12 describes the significant fields shown in the display.
The following is sample output from show ip ospf database command with the summary keyword:
Router# show ip ospf database summaryOSPF Router with id(192.168.239.66) (Process ID 300)Displaying Summary Net Link States(Area 0.0.0.0)LS age: 1401Options: (No TOS-capability)LS Type: Summary Links(Network)Link State ID: 10.187.240.0 (summary Network Number)Advertising Router: 10.187.241.5LS Seq Number: 80000072Checksum: 0x84FFLength: 28Network Mask: 255.255.255.0 TOS: 0 Metric: 1Table 13 describes the significant fields shown in the display.
The following is sample output from show ip ospf database command with the database-summary keyword:
Router# show ip ospf database database-summaryOSPF Router with ID (172.19.65.21) (Process ID 1)Area ID Router Network Sum-Net Sum-ASBR Subtotal Delete Maxage202 1 0 0 0 1 0 0AS External 0 0 0Total 1 0 0 0 1Table 14 describes the significant fields shown in the display.
show ip ospf flood-list
To display a list of OSPF link-state advertisements (LSAs) waiting to be flooded over an interface, use the show ip ospf flood-list command in EXEC mode.
show ip ospf flood-list interface-type interface-number
Syntax Description
interface-type
Interface type over which the LSAs will be flooded.
interface-number
Interface number over which the LSAs will be flooded.
Command Modes
EXEC
Command History
Usage Guidelines
Use this command to observe OSPF packet pacing.
Examples
The following is sample output of the show ip ospf flood-list command:
Router# show ip ospf flood-list ethernet 1Interface Ethernet1, Queue length 20Link state flooding due in 12 msecType LS ID ADV RTR Seq NO Age Checksum5 10.2.195.0 192.168.0.163 0x80000009 0 0xFB615 10.1.192.0 192.168.0.163 0x80000009 0 0x29385 10.2.194.0 192.168.0.163 0x80000009 0 0x7575 10.1.193.0 192.168.0.163 0x80000009 0 0x1E425 10.2.193.0 192.168.0.163 0x80000009 0 0x124D5 10.1.194.0 192.168.0.163 0x80000009 0 0x134CTable 15 describes the significant fields shown in the display.
show ip ospf interface
To display OSPF-related interface information, use the show ip ospf interface command in EXEC mode.
show ip ospf interface [interface-type interface-number]
Syntax Description
Command Modes
EXEC
Command History
Examples
The following is sample output of the show ip ospf interface command when Ethernet interface 0 is specified:
Router# show ip ospf interface ethernet 0Ethernet 0 is up, line protocol is upInternet Address 192.168.254.202, Mask 255.255.255.0, Area 0.0.0.0AS 201, Router ID 192.77.99.1, Network Type BROADCAST, Cost: 10Transmit Delay is 1 sec, State OTHER, Priority 1Designated Router id 192.168.254.10, Interface address 192.168.254.10Backup Designated router id 192.168.254.28, Interface addr 192.168.254.28Timer intervals configured, Hello 10, Dead 60, Wait 40, Retransmit 5Hello due in 0:00:05Neighbor Count is 8, Adjacent neighbor count is 2Adjacent with neighbor 192.168.254.28 (Backup Designated Router)Adjacent with neighbor 192.168.254.10 (Designated Router)Table 16 describes the significant fields shown in the display.
show ip ospf neighbor
To display OSPF-neighbor information on a per-interface basis, use the show ip ospf neighbor command in EXEC mode.
show ip ospf neighbor [interface-type interface-number] [neighbor-id] [detail]
Syntax Description
Command Modes
EXEC
Command History
Examples
The following is sample output from the show ip ospf neighbor command showing a single line of summary information for each neighbor:
Router# show ip ospf neighborID Pri State Dead Time Address Interface10.199.199.137 1 FULL/DR 0:00:31 192.168.80.37 Ethernet0172.16.48.1 1 FULL/DROTHER 0:00:33 172.16.48.1 Fddi0172.16.48.200 1 FULL/DROTHER 0:00:33 172.16.48.200 Fddi010.199.199.137 5 FULL/DR 0:00:33 172.16.48.189 Fddi0The following is sample output showing summary information about the neighbor that matches the neighbor ID:
Router# show ip ospf neighbor 10.199.199.137Neighbor 10.199.199.137, interface address 192.168.80.37In the area 0.0.0.0 via interface Ethernet0Neighbor priority is 1, State is FULLOptions 2Dead timer due in 0:00:32Link State retransmission due in 0:00:04Neighbor 10.199.199.137, interface address 172.16.48.189In the area 0.0.0.0 via interface Fddi0Neighbor priority is 5, State is FULLOptions 2Dead timer due in 0:00:32Link State retransmission due in 0:00:03If you specify the interface along with the neighbor ID, the Cisco IOS software displays the neighbors that match the neighbor ID on the interface, as in the following sample display:
Router# show ip ospf neighbor ethernet 0 10.199.199.137Neighbor 10.199.199.137, interface address 192.168.80.37In the area 0.0.0.0 via interface Ethernet0Neighbor priority is 1, State is FULLOptions 2Dead timer due in 0:00:37Link State retransmission due in 0:00:04You can also specify the interface without the neighbor ID to show all neighbors on the specified interface, as in the following sample display:
Router# show ip ospf neighbor fddi 0ID Pri State Dead Time Address Interface172.16.48.1 1 FULL/DROTHER 0:00:33 172.16.48.1 Fddi0172.16.48.200 1 FULL/DROTHER 0:00:32 172.16.48.200 Fddi010.199.199.137 5 FULL/DR 0:00:32 172.16.48.189 Fddi0The following is sample output from the show ip ospf neighbor detail command:
Router# show ip ospf neighbor detailNeighbor 192.168.5.2, interface address 10.225.200.28In the area 0 via interface Ethernet1Neighbor priority is 1, State is FULL, 6 state changesDR is 10.225.200.28 BDR is 10.225.200.30Options is 0x42Dead timer due in 00:00:36Neighbor is up for 00:09:46Index 1/1, retransmission queue length 0, number of retransmission 1First 0x0(0)/0x0(0) Next 0x0(0)/0x0(0)Last retransmission scan length is 1, maximum is 1Last retransmission scan time is 0 msec, maximum is 0 msecTable 17 describes the significant fields shown in the displays.
show ip ospf request-list
To display a list of all link-state advertisements (LSAs) requested by a router, use the show ip ospf request-list command in EXEC mode.
show ip ospf request-list [neighbor] [interface] [interface-neighbor]
Syntax Description
Command Modes
EXEC
Command History
Usage Guidelines
The information displayed by the show ip ospf request-list command is useful in debugging OSPF routing operations.
Examples
The following is sample output from the show ip ospf request-list command:
Router# show ip ospf request-list serial 0OSPF Router with ID (192.168.1.11) (Process ID 1)Neighbor 192.168.1.12, interface Serial0 address 172.16.1.12Type LS ID ADV RTR Seq NO Age Checksum1 192.168.1.12 192.168.1.12 0x8000020D 8 0x6572show ip ospf retransmission-list
To display a list of all link-state advertisements (LSAs) waiting to be resent, use the show ip ospf retransmission-list command in EXEC mode.
show ip ospf retransmission-list [neighbor] [interface] [interface-neighbor]
Syntax Description
Command Modes
EXEC
Command History
Usage Guidelines
The information displayed by the show ip ospf retransmission-list command is useful in debugging OSPF routing operations.
Examples
The following is sample output from the show ip ospf retransmission-list command:
Router# show ip ospf retransmission-list serial 0OSPF Router with ID (192.168.1.12) (Process ID 1)Neighbor 192.168.1.11, interface Serial0 address 172.16.1.11Link state retransmission due in 3764 msec, Queue length 2Type LS ID ADV RTR Seq NO Age Checksum1 192.168.1.12 192.168.1.12 0x80000210 0 0xB196show ip ospf summary-address
To display a list of all summary address redistribution information configured under an OSPF process, use the show ip ospf summary-address command in EXEC mode.
show ip ospf [process-id] summary-address
Syntax Description
Command Modes
EXEC
Command History
Usage Guidelines
The process-id argument can be entered as a decimal number or as an IP address format.
Examples
The following is sample output from the show ip ospf summary-address command:
Router# show ip ospf summary-addressOSPF Process 2, Summary-address10.2.0.0/255.255.0.0 Metric -1, Type 0, Tag 010.2.0.0/255.255.0.0 Metric -1, Type 0, Tag 10show ip ospf virtual-links
To display parameters and the current state of OSPF virtual links, use the show ip ospf virtual-links command in EXEC mode.
show ip ospf virtual-links
Syntax Description
This command has no arguments or keywords.
Command Modes
EXEC
Command History
Usage Guidelines
The information displayed by the show ip ospf virtual-links command is useful in debugging OSPF routing operations.
Examples
The following is sample output from the show ip ospf virtual-links command:
Router# show ip ospf virtual-linksVirtual Link to router 192.168.101.2 is upTransit area 0.0.0.1, via interface Ethernet0, Cost of using 10Transmit Delay is 1 sec, State POINT_TO_POINTTimer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5Hello due in 0:00:08Adjacency State FULLTable 18 describes the significant fields shown in the display.
summary-address (OSPF)
To create aggregate addresses for OSPF, use the summary-address command in router configuration mode. To restore the default, use the no form of this command.
summary-address {{ip-address mask} | {prefix mask}} [not-advertise] [tag tag]
no summary-address {{ip-address mask } | {prefix mask}} [not-advertise] [tag tag]
Syntax Description
Defaults
This command is disabled by default.
Command Modes
Router configuration
Command History
Usage Guidelines
Routes learned from other routing protocols can be summarized. The metric used to advertise the summary is the smallest metric of all the more specific routes. This command helps reduce the size of the routing table.
Using this command for OSPF causes an OSPF Autonomous System Boundary Router (ASBR) to advertise one external route as an aggregate for all redistributed routes that are covered by the address. For OSPF, this command summarizes only routes from other routing protocols that are being redistributed into OSPF. Use the area range command for route summarization between OSPF areas.
OSPF does not support summary-address 0.0.0.0 0.0.0.0.
Examples
In the following example, the summary address 10.1.0.0 includes address 10.1.1.0, 10.1.2.0, 10.1.3.0, and so on. Only the address 10.1.0.0 is advertised in an external link-state advertisement.
summary-address 10.1.0.0 255.255.0.0Related Commands
timers lsa-group-pacing
To change the interval at which OSPF link-state advertisements (LSAs) are collected into a group and refreshed, checksummed, or aged, use the timers lsa-group-pacing command in router configuration mode. To restore the default value, use the no form of this command.
timers lsa-group-pacing seconds
no timers lsa-group-pacing
Syntax Description
seconds
Number of seconds in the interval at which LSAs are grouped and refreshed, checksummed, or aged. The range is from 10 to 1800 seconds. The default value is 240 seconds.
Defaults
This command is disabled by default.
Command Modes
Router configuration
Command History
Usage Guidelines
OSPF LSA group pacing is enabled by default. For typical customers, the default group pacing interval for refreshing, checksumming, and aging is appropriate and you need not configure this feature.
The duration of the LSA group pacing is inversely proportional to the number of LSAs the router is handling. For example, if you have about 10,000 LSAs, decreasing the pacing interval would benefit you. If you have a very small database (40 to 100 LSAs), increasing the pacing interval to 10 to 20 minutes might benefit you slightly.
Examples
The following example changes the OSPF pacing between LSA groups to 60 seconds:
router ospftimers lsa-group-pacing 60timers spf
To configure the delay time between when OSPF receives a topology change and when it starts a shortest path first (SPF) calculation, and the hold time between two consecutive SPF calculations, use the timers spf command in router configuration mode. To return to the default timer values, use the no form of this command.
timers spf spf-delay spf-holdtime
no timers spf spf-delay spf-holdtime
Syntax Description
Defaults
This command is disabled by default.
Command Modes
Router configuration
Command History
Usage Guidelines
Setting the delay and hold time low causes routing to switch to the alternate path more quickly in the event of a failure. However, it requires the router to use more CPU processing time.
Examples
The following example changes the delay to 10 seconds and the hold time to 20 seconds:
timers spf 10 20
