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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.
To enable authentication for an OSPF area, use the area authentication router configuration command. 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]
area-id | Identifier of the area for which authentication is to be enabled. The identifier can be specified as either a decimal value or an IP address. |
message-digest | (Optional) Enables MD5 authentication on the area specified by area-id. |
Type 0 authentication (no authentication)
Router configuration
This command first appeared in Cisco IOS Release 10.0. The message-digest keyword first appeared in Cisco IOS Release 11.0.
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 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.
The following example mandates authentication for areas 0 and 36.0.0.0 of OSPF routing process 201. Authentication keys are also provided.
interface ethernet 0 ip address 131.119.251.201 255.255.255.0 ip ospf authentication-key adcdefgh ! interface ethernet 1 ip address 36.56.0.201 255.255.0.0 ip ospf authentication-key ijklmnop ! router ospf 201 network 36.0.0.0 0.255.255.255 area 36.0.0.0 network 131.119.0.0 0.0.255.255 area 0 area 36.0.0.0 authentication area 0 authentication
You can use the master indexes or search online to find documentation of related commands.
area default-cost
area stub
ip ospf authentication-key
ip ospf message-digest-key
To specify a cost for the default summary route sent into a stub area, use the area default-cost router configuration command. To remove the assigned default route cost, use the no form of this command.
area area-id default-cost cost
area-id | Identifier for the stub area. The identifier can be specified as either a decimal value or as an IP address. |
cost | Cost for the default summary route used for a stub area. The acceptable value is a 24-bit number. |
Cost of 1
Router configuration
This command first appeared in Cisco IOS Release 10.0.
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.
The following example assigns a default-cost of 20 to stub network 36.0.0.0:
interface ethernet 0 ip address 36.56.0.201 255.255.0.0 ! router ospf 201 network 36.0.0.0 0.255.255.255 area 36.0.0.0 area 36.0.0.0 stub area 36.0.0.0 default-cost 20
You can use the master indexes or search online to find documentation of related commands.
To configure an area as a not so stubby area (NSSA), use the area nssa router configuration command. To remove the nssa distinction from the area, use the no form of this command.
area area-id nssa [no-redistribution] [default-information-originate]
area-id | Identifier of the area for which authentication is to be enabled. The identifier can be specified as either a decimal value or an IP address. |
no-redistribution | (Optional) Used when the router is a NSSA ABR and you want the redistribute command to import routes only into the normal areas, but not into the NSSA area. |
default-information- | (Optional) Used to generate a Type 7 default into the NSSA area. This argument only takes effect on NSSA ABR. |
No NSSA area is defined.
Router configuration
This command first appeared in Cisco IOS Release 10.0.
In the following example, NSSA authentication is enabled on area 1:
router ospf1 redistribute rip subnets network 172.19.92.0.0.0.0.255 area 1 area 1 nssa
To consolidate and summarize routes at an area boundary, use the area range router configuration command. To disable this function, use the no form of this command.
area area-id range address mask [advertise | not-advertise]
area-id | Identifier of the area about which routes are to be summarized. It can be specified as either a decimal value or as an IP address. |
address | IP address. |
mask | IP mask. |
advertise | (Default) Sets the address range status to advertise and generates a Type 3 summary LSA. |
not-advertise | Sets the address range status to DoNotAdvertise. The Type 3 summary LSA is suppressed and the component networks remain hidden from other networks. |
Disabled
Router configuration
This command first appeared in Cisco IOS Release 10.0.
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 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.
The following example specifies one summary route to be advertised by the ABR to other areas for all subnets on network 36.0.0.0 and for all hosts on network 192.42.110.0:
interface ethernet 0 ip address 192.42.110.201 255.255.255.0 ! interface ethernet 1 ip address 36.56.0.201 255.255.0.0 ! router ospf 201 network 36.0.0.0 0.255.255.255 area 36.0.0.0 network 192.42.110.0 0.0.0.255 area 0 area 36.0.0.0 range 36.0.0.0 255.0.0.0 area 0 range 192.42.110.0 255.255.255.0
To define an area as a stub area, use the area stub router configuration command. To disable this function, use the no form of this command.
area area-id stub [no-summary]
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. |
No stub area is defined.
Router configuration
This command first appeared in Cisco IOS Release 10.0.
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 (LSA) 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.
The following example assigns a default cost of 20 to stub network 36.0.0.0:
interface ethernet 0 ip address 36.56.0.201 255.255.0.0 ! router ospf 201 network 36.0.0.0 0.255.255.255 area 36.0.0.0 area 36.0.0.0 stub area 36.0.0.0 default-cost 20
You can use the master indexes or search online to find documentation of related commands.
area authentication
area default-cost
area-id | Area ID assigned to the transit area for the virtual link. This can be either a decimal value or a valid IP address. There is no default. |
router-id | Router ID associated with the virtual link neighbor. The router ID appears in the show ip ospf display. It is internally derived by each router from the router's interface IP addresses. This value must be entered in the format of an IP address. There is no default. |
hello-interval seconds | (Optional) Time in seconds between the hello packets that the Cisco IOS software sends on an interface. Unsigned integer value to be advertised in the software's hello packets. The value must be the same for all routers and access servers attached to a common network. The default is 10 seconds. |
retransmit-interval seconds | (Optional) Time in seconds between link state advertisement retransmissions for adjacencies belonging to the interface. Expected round-trip delay between any two routers on the attached network. The value must be greater than the expected round-trip delay. The default is 5 seconds. |
transmit-delay seconds | (Optional) Estimated time in seconds it takes to transmit a link state update packet on the interface. Integer value that must be greater than zero. Link state advertisements in the update packet have their age incremented by this amount before transmission. The default value is 1 second. |
dead-interval seconds | (Optional) Time in seconds that a software's hello packets are not seen before its neighbors declare the router down. Unsigned integer value. The default is four times the hello interval, or 40 seconds. As with the hello interval, this value must be the same for all routers and access servers attached to a common network. |
authentication-key key | (Optional) Password to be used by neighboring routers. Any continuous string of characters that you can enter from the keyboard up to 8 bytes long. This string acts as a key that will allow the authentication procedure to generate or verify the authentication field in the OSPF header. This key is inserted directly into the OSPF header when originating 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 route OSPF traffic. The password is encrypted in the configuration file if the service password-encryption command is enabled. There is no default value. |
message-digest-key keyid md5 key | (Optional) Key identifier and password to be used by neighboring routers and this router for MD5 authentication. The keyid is a number in the range 1 to 255. The key is an alphanumeric string of up to 16 characters. All neighboring routers on the same network must have the same key identifier and key to be able to route OSPF traffic. There is no default value. |
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 keyid md5 key: No key is predefined.
Router configuration
This command first appeared in Cisco IOS Release 10.0. The following keywords and arguments first appeared in Cisco IOS Release 11.0: message-digest-key keyid md5 key.
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 keyid md5 key are ignored. Therefore, specify any optional arguments before such a keyword-argument combination.
The following example establishes a virtual link with default values for all optional parameters:
router ospf 201 network 36.0.0.0 0.255.255.255 area 36.0.0.0 area 36.0.0.0 virtual-link 36.3.4.5
The following example establishes a virtual link with MD5 authentication:
router ospf 201 network 36.0.0.0 0.255.255.255 area 36.0.0.0 area 36.0.0.0 virtual-link 36.3.4.5 message-digest-key 3 md5 sa5721bk47
You can use the master indexes or search online to find documentation of related commands.
area authentication
service password-encryption
show ip ospf
To clear redistribution based on the OSPF routing process ID, use the clear ip ospf command.
clear ip ospf [pid] {process | redistribution | counters [neighbor [intf] [nbr-id]]}
pid | (Optional) Process ID. |
process | Reset OSPF process. |
redistribution | Clear OSPF route redistribution. |
counters | OSPF counters. |
neighbor | Neighbor statistics per interface. |
intf | Neighbor interface. |
nbr-id | Neighbor ID. |
Router configuration
Use the pid option to clear only one OSPF process. If the pid option is not specified, all OSPF processes are cleared.
The following example clears all OSPF processes:
clear ip ospf process !
You can use the master indexes or search online to find documentation of related commands.
To generate a default route into an OSPF routing domain, use the default-information originate router configuration command. To disable this feature, use the no form of this command.
default-information originate [always] [metric metric-value] [metric-type type-value]
originate | Causes the Cisco IOS software to generate a default external route into an OSPF domain if the software already has a default route and you want to propagate to other routers. |
always | (Optional) Always advertises the default route regardless of whether the software has a default route. |
metric metric-value | (Optional) Metric used for generating the default route. If you omit a value and do not specify a value using the default-metric router configuration command, the default metric value is 10. The value used is specific to the protocol. |
metric-type type-value | (Optional) External link type associated with the default route advertised into the OSPF routing domain. It can be one of the following values: 1—Type 1 external route 2—Type 2 external route The default is Type 2 external route. |
level-1 | Level 1 routes are redistributed into other IP routing protocols independently. It specifies if IS-IS advertises network 0.0.0.0 into the Level 1 area. |
level-1-2 | Both Level 1 and Level 2 routes are redistributed into other IP routing protocols. It specifies if IS-IS advertises network 0.0.0.0 into both levels in a single command. |
level-2 | Level 2 routes are redistributed into other IP routing protocols independently. It specifies if IS-IS advertises network 0.0.0.0 into the Level 2 subdomain. |
route-map map-name | (Optional) Routing process will generate the default route if the route map is satisfied. |
Disabled
Router configuration
This command first appeared in Cisco IOS Release 10.0.
Whenever you use the redistribute or the default-information router configuration commands 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.
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 109 redistribute igrp 108 metric 100 subnets default-information originate metric 100 metric-type 1
You can use the master indexes or search online to find documentation of related commands.
redistribute
To set default metric values for the OSPF routing protocol, use this form of the default-metric router configuration command. To return to the default state, use the no form of this command.
default-metric number
number | Default metric value appropriate for the specified routing protocol. |
Built-in, automatic metric translations, as appropriate for each routing protocol
Router configuration
This command first appeared in Cisco IOS Release 10.0.
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.
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 rip default-metric 10 redistribute ospf 109
You can use the master indexes or search online to find documentation of related commands.
redistribute
To assign a password to be used by neighboring routers that are using OSPF's simple password authentication, use the ip ospf authentication-key interface configuration command. To remove a previously assigned OSPF password, use the no form of this command.
ip ospf authentication-key password
password | Any continuous string of characters that can be entered from the keyboard up to 8 bytes in length. |
No password is specified.
Interface configuration
This command first appeared in Cisco IOS Release 10.0.
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.
In the following example, the authentication key is enabled with the string yourpass:
ip ospf authentication-key yourpass
You can use the master indexes or search online to find documentation of related commands.
To explicitly specify the cost of sending a packet on an interface, use the ip ospf cost interface configuration command. To reset the path cost to the default value, use the no form of this command.
ip ospf cost cost
cost | Unsigned integer value expressed as the link state metric. It can be a value in the range 1 to 65535. |
No default cost is predefined.
Interface configuration
This command first appeared in Cisco IOS Release 10.0.
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:
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.
The following example sets the interface cost value to 65:
ip ospf cost 65
seconds | Unsigned integer that specifies the interval in seconds; the value must be the same for all nodes on the network. |
Four times the interval set by the ip ospf hello-interval command
Interface configuration
This command first appeared in Cisco IOS Release 10.0.
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.
The following example sets the OSPF dead interval to 60 seconds:
interface ethernet 1
ip ospf dead-interval 60
You can use the master indexes or search online to find documentation of related commands.
To configure OSPF to treat the interface as an OSPF demand circuit, use the ip ospf demand-circuit interface configuration command. To remove the demand circuit designation from the interface, use the no form of this command.
ip ospf demand-circuitThis command has no arguments or keywords.
The circuit is not a demand circuit.
Interface configuration
This command first appeared in Cisco IOS Release 11.2.
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.
The following example sets the configures an ISDN on demand circuit:
router ospf1 network 18.0.3.0.0.0.0.25 area 0 interface BRIO ip ospf demand-circuit
To specify the interval between hello packets that the Cisco IOS software sends on the interface, use the ip ospf hello-interval interface configuration command. To return to the default time, use the no form of this command.
ip ospf hello-interval seconds
seconds | Unsigned integer that specifies the interval in seconds. The value must be the same for all nodes on a specific network. |
10 seconds
Interface configuration
This command first appeared in Cisco IOS Release 10.0.
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.
The following example sets the interval between hello packets to 15 seconds:
interface ethernet 1 ip ospf hello-interval 15
You can use the master indexes or search online to find documentation of related commands.
keyid | An identifier in the range 1 to 255. |
key | Alphanumeric password of up to 16 bytes. |
OSPF MD5 authentication is disabled.
Interface configuration
This command first appeared in Cisco IOS Release 11.0.
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 1 ip ospf message-digest-key 100 md5 OLD
You change the configuration to the following:
interface ethernet 1 ip ospf message-digest-key 101 md5 NEW
The 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 1 no ip ospf message-digest-key 100
Then, 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.
The following example sets a new key 19 with the password 8ry4222:
interface ethernet 1 ip ospf message-digest-key 10 md5 xvv560qle ip ospf message-digest-key 19 md5 8ry4222
You can use the master indexes or search online to find documentation of related commands.
area authentication
This command has no arguments or keywords.
Disabled
Global configuration
This command first appeared in Cisco IOS Release 10.0.
This feature makes it easier to identify a router because it is displayed by name rather than by its router ID or neighbor ID.
The following example configures OSPF to look up DNS names for use in all OSPF show EXEC command displays:
ip ospf name-lookup
The following is sample output from the show ip ospf database EXEC command, for example, once you have enabled the DNS name lookup feature:
Router# show ip ospf database
OSPF Router with id (160.89.41.1) (Autonomous system 109)
Router Link States (Area 0.0.0.0)
Link ID ADV Router Age Seq# Checksum Link count
160.89.41.1 router 381 0x80000003 0x93BB 4
160.89.34.2 neon 380 0x80000003 0xD5C8 2
Net Link States (Area 0.0.0.0)
Link ID ADV Router Age Seq# Checksum
160.89.32.1 router 381 0x80000001 0xC117
broadcast | Sets the network type to broadcast. |
non-broadcast | Sets the network type to nonbroadcast. |
point-to-multipoint | Sets the network type to point-to-multipoint. |
Depends on the network type.
Interface configuration
This command first appeared in Cisco IOS Release 10.0. The point-to-multipoint keyword first appeared in Cisco IOS Release 10.3.
Using this feature, you can configure broadcast networks as nonbroadcast multiaccess (NBMA) networks when, for example, you have routers in your network that do not support multicast addressing. You can also configure nonbroadcast multiaccess networks (such as X.25, Frame Relay, and SMDS) as broadcast networks. This feature saves you from having 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 network. This is not true for some cases, for example, because of cost constraints or when you have only 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. Note that you do not need to configure neighbors when using this feature.
If this command is issued on an interface that does not allow it, it will be ignored.
The following example sets your OSPF network as a broadcast network:
interface serial 0
ip address 160.89.77.17 255.255.255.0 ip ospf network broadcast encapsulation frame-relay
You can use the master indexes or search online to find documentation of related commands.
frame-relay map
neighbor (OSPF)
x25 map
number | 8-bit unsigned integer that specifies the priority. The range is from 0 to 255. |
Priority of 1
Interface configuration
This command first appeared in Cisco IOS Release 10.0.
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 only configured for interfaces to multiaccess networks (in other words, not point-to-point networks).
This priority value is used when you configure OSPF for nonbroadcast networks using the neighbor router configuration command for OSPF.
The following example sets the router priority value to 4:
interface ethernet 0
ip ospf priority 4
You can use the master indexes or search online to find documentation of related commands.
ip ospf network
neighbor (OSPF)
To specify the time between link state advertisement retransmissions for adjacencies belonging to the interface, use the ip ospf retransmit-interval interface configuration command. To return to the default value, use the no form of this command.
ip ospf retransmit-interval seconds
seconds | Time in seconds between retransmissions. It must be greater than the expected round-trip delay between any two routers on the attached network. The range is 1 to 65535 seconds. The default is 5 seconds. |
5 seconds
Interface configuration
This command first appeared in Cisco IOS Release 10.0.
When a router sends a link state advertisement (LSA) to its neighbor, it keeps the LSA until it receives back the acknowledgment. If it receives no acknowledgment in seconds, it will retransmit 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.
The following example sets the retransmit-interval value to 8 seconds:
interface ethernet 2
ip ospf retransmit-interval 8
To set the estimated time it takes to transmit a link state update packet on the interface, use the ip ospf transmit-delay interface configuration command. To return to the default value, use the no form of this command.
ip ospf transmit-delay seconds
seconds | Time in seconds that it takes to transmit a link state update.The range is 1 to 65535 seconds. The default is 1 second. |
1 second
Interface configuration
This command first appeared in Cisco IOS Release 10.0.
Link state advertisements 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.
The following example sets the retransmit-delay value to 3 seconds:
interface ethernet 0
ip ospf transmit-delay 3
ip-address | Interface IP address of the neighbor. |
priority number | (Optional) 8-bit number indicating the router priority value of the nonbroadcast neighbor associated with the IP address specified. The default is 0. |
poll-interval seconds | (Optional) Unsigned integer value reflecting the poll interval. RFC 1247 recommends that this value be much larger than the hello interval. The default is 2 minutes (120 seconds). |
No configuration is specified.
Router configuration
This command first appeared in Cisco IOS Release 10.0.
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. See the x25 map and frame-relay map commands in "X.25 Commands" and "Frame Relay Commands" chapters, respectively, in the 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 has to be on the primary address of the interface.
If a neighboring router has become inactive (hello packets have not been seen 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 non-zero priority, that is, routers which are eligible to become designated routers (DR) and backup designated routers (BDR). After DR and BDR are selected, DR and BDR will then start sending hello packets to all neighbors in order to form adjacencies.
The following example declares a router at address 131.108.3.4 on a nonbroadcast network, with a priority of 1 and a poll-interval of 180:
router ospf
neighbor 131.108.3.4 priority 1 poll-interval 180
You can use the master indexes or search online to find documentation of related commands.
To define the interfaces on which OSPF runs and to define the area ID for those interfaces, use the network area router configuration command. To disable OSPF routing for interfaces defined with the address wildcard-mask pair, use the no form of this command.
network address wildcard-mask area area-id
address | IP address. |
wildcard-mask | IP-address-type mask that includes "don't care" bits. |
area-id | Area that is to be associated with the OSPF address range. It can be specified as either a decimal value or as an IP address. If you intend to associate areas with IP subnets, you can specify a subnet address as the area-id. |
Disabled
Router configuration
This command first appeared in Cisco IOS Release 10.0.
The 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 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 area-id.
For OSPF to operate on the interface, that interface's primary address 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 address/wildcard-mask pair for each interface as follows:
1. The wildcard-mask is logically ORed with the interface IP address.
2. The wildcard-mask is logically ORed with address in the network command.
3. The software compares the two resulting values.
4. If they match, OSPF is enabled on the associated interface and this interface is attached to the OSPF area specified.
There is no limit to the number of network area commands used on the router.
In the following partial example, OSPF routing process 109 is initialized, and four OSPF areas are defined: 10.9.50.0, 2, 3, and 0. Areas 10.9.50.0, 2, and 3 mask specific address ranges, while area 0 enables OSPF for all other networks.
interface ethernet 0 ip address 131.108.20.1 255.255.255.0 router ospf 109 network 131.108.20.0 0.0.0.255 area 10.9.50.0 network 131.108.0.0 0.0.255.255 area 2 network 131.109.10.0 0.0.0.255 area 3 network 0.0.0.0 255.255.255.255 area 0
You can use the master indexes or search online to find documentation of related commands.
To control how OSPF calculates default metrics for the interface, use the ospf auto-cost router configuration command. To assign cost based only on the interface type, use the no form of this command.
ospf auto-cost reference-bandwidth ref-bw
ref-bw | Rate in megabits per second (bandwidth). The range is 1 to 4294967; the default is 100. |
100 Mbits
Router configuration
This command first appeared in Cisco IOS Release 11.2.
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, while 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 ospf auto-cost command.
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 1 ospf auto-cost reference-bandwidth 1000
You can use the master indexes or search online to find documentation of related commands.
To configure the router to send a syslog message when the state of an OSPF neighbor changes, use the ospf log-adj-changes router configuration command. To turn off this feature, use the no form of this command.
ospf log-adj-changesThis command has no arguments or keywords.
No such syslog message is sent.
Router configuration
This command first appeared in Cisco IOS Release 11.2.
Configure this command if you want to know about OSPF neighbor changes without turning on the debugging command debug ip ospf adjacency. The ospf log-adj-changes command provides a higher level view of changes to the state of the peer relationship with less output.
The following example configures the router to send a syslog message for any neighbor state changes:
ospf log-adj-changes
To use a fixed router-id, use the router-id command. To force OSPF to use the previous OSPF router-id behavior, use the no form of this command.
router-id ip-address
ip-address | Router ID in IP address format. |
No OSPF routing process is defined.
Router configuration
This command first appeared in Cisco IOS Release 10.0.
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.
The following example specifies a fixed router-id:
router-id 1.1.1.1
You can use the master indexes or search online to find documentation of related commands.
To configure an OSPF routing process, use the router ospf global configuration command. To terminate an OSPF routing process, use the no form of this command.
router ospf process-id
process-id | Internally used identification parameter for an OSPF routing process. It is locally assigned and can be any positive integer. A unique value is assigned for each OSPF routing process. |
ip-address | Is the address of the router ID. |
No OSPF routing process is defined.
Global configuration
This command first appeared in Cisco IOS Release 10.0.
You can specify multiple OSPF routing processes in each router.
You can configure an arbitrary value in the ip-address format for each router. However, each router ID must be unique.
The following example shows how to configure an OSPF routing process and assign a process number of 109:
router ospf 109
You can use the master indexes or search online to find documentation of related commands.
To display general information about OSPF routing processes, use the show ip ospf EXEC command.
show ip ospf [process-id]
process-id | (Optional) Process ID. If this argument is included, only information for the specified routing process is included. |
EXEC
This command first appeared in Cisco IOS Release 10.0.
The following is sample output from the show ip ospf command when entered without a specific OSPF process ID:
Router# show ip ospf Routing Process "ospf 201" with ID 192.42.110.200 Supports only single TOS(TOS0) route It is an area border and autonomous system boundary router Summary Link update interval is 0:30:00 and the update due in 0:16:26 External Link update interval is 0:30:00 and the update due in 0:16:27 Redistributing External Routes from, igrp 200 with metric mapped to 2, includes subnets in redistribution rip with metric mapped to 2 igrp 2 with metric mapped to 100 igrp 32 with metric mapped to 1 Number of areas in this router is 3 Area 192.42.110.0 Number of interfaces in this area is 1 Area has simple password authentication SPF algorithm executed 6 times Area ranges are Link State Update Interval is 0:30:00 and due in 0:16:55 Link State Age Interval is 0:20:00 and due in 0:06:55
Table 26 describes significant fields shown in the display.
| Field | Description |
|---|---|
Routing process "ospf 201" with ID 192.42.110.200 | Process ID and OSPF router ID. |
Supports ... | Number of Types of service supported (Type 0 only). |
It is ... | Possible types are internal, area border, or autonomous system boundary. |
Summary Link update interval | Specify summary update interval in hours:minutes:seconds, and time to next update. |
External Link update interval | Specify external update interval in hours:minutes:seconds, and time to next update. |
Redistributing External Routes from | Lists of redistributed routes, by protocol. |
Number of areas | Number of areas in router, area addresses, and so on. |
Link State Update Interval | Specify router and network link state update interval in hours:minutes:seconds, and time to next update. |
Link State Age Interval | Specify max-aged update deletion interval and time until next database cleanup in hours:minutes:seconds. |
This command has no arguments or keywords.
Privileged EXEC
This command first appeared in Cisco IOS Release 10.0.
The following is sample output from the show ip ospf border-routers command:
Router# show ip ospf border-routers OSPF Process 109 internal Routing Table Destination Next Hop Cost Type Rte Type Area SPF No 160.89.97.53 144.144.1.53 10 ABR INTRA 0.0.0.3 3 160.89.103.51 160.89.96.51 10 ABR INTRA 0.0.0.3 3 160.89.103.52 160.89.96.51 20 ASBR INTER 0.0.0.3 3 160.89.103.52 144.144.1.53 22 ASBR INTER 0.0.0.3 3
Table 27 describes the fields shown in the display.
| Field | Description |
|---|---|
Destination | Destination's router ID. |
Next Hop | Next hop toward the destination. |
Cost | Cost of using this route. |
Type | The router type of the destination; it is either an area border router (ABR) or autonomous system boundary router (ASBR) or both. |
Rte Type | The type of this route, it is either an intra-area or interarea route. |
Area | The area ID of the area that this route is learned from. |
SPF No | The internal number of SPF calculation that installs this route. |
Use the show ip ospf database EXEC command to display lists of information related to the OSPF database for a specific router. The various forms of this command deliver information about different OSPF link state advertisements.
show ip ospf [process-id area-id] database
process-id | (Optional) Internally used identification parameter. It is locally assigned and can be any positive integer number. The number used here is the number assigned administratively when enabling the OSPF routing process. |
area-id | (Optional) Area number associated with the OSPF address range defined in the network router configuration command used to define the particular area. |
link-state-id | (Optional) Identifies the portion of the Internet environment that is being described by the advertisement. The value entered depends on the advertisement's LS type. It must be entered in the form of an IP address. When the link state advertisement is describing a network, the link-state-id can take one of two forms:
When the link state advertisement is describing a router, the link state ID is always the described router's OSPF router ID. When an autonomous system external advertisement (LS Type = 5) is describing a default route, its link state ID is set to Default Destination (0.0.0.0). |
When entered with the optional keyword asb-summary, external, network, router, summary, or database-summary, different displays result. Examples and brief descriptions of each form follow.
EXEC
This command first appeared in Cisco IOS Release 10.0. The following form of the command first appeared in Cisco IOS Release 11.0:
show ip ospf [process-id area-id] database [database-summary].
The following is sample output from the show ip ospf database command when no arguments or keywords are used:
Router# show ip ospf database
OSPF Router with id(190.20.239.66) (Process ID 300)
Displaying Router Link States(Area 0.0.0.0)
Link ID ADV Router Age Seq# Checksum Link count
155.187.21.6 155.187.21.6 1731 0x80002CFB 0x69BC 8
155.187.21.5 155.187.21.5 1112 0x800009D2 0xA2B8 5
155.187.1.2 155.187.1.2 1662 0x80000A98 0x4CB6 9
155.187.1.1 155.187.1.1 1115 0x800009B6 0x5F2C 1
155.187.1.5 155.187.1.5 1691 0x80002BC 0x2A1A 5
155.187.65.6 155.187.65.6 1395 0x80001947 0xEEE1 4
155.187.241.5 155.187.241.5 1161 0x8000007C 0x7C70 1
155.187.27.6 155.187.27.6 1723 0x80000548 0x8641 4
155.187.70.6 155.187.70.6 1485 0x80000B97 0xEB84 6
Displaying Net Link States(Area 0.0.0.0)
Link ID ADV Router Age Seq# Checksum
155.187.1.3 192.20.239.66 1245 0x800000EC 0x82E
Displaying Summary Net Link States(Area 0.0.0.0)
Link ID ADV Router Age Seq# Checksum
155.187.240.0 155.187.241.5 1152 0x80000077 0x7A05
155.187.241.0 155.187.241.5 1152 0x80000070 0xAEB7
155.187.244.0 155.187.241.5 1152 0x80000071 0x95CB
Table 28 describes significant fields shown in the display.
| Field | Description |
|---|---|
Link ID | Router ID number. |
ADV Router | Advertising router's ID. |
Age | Link state age. |
Seq# | Link state sequence number (detects old or duplicate link state advertisements). |
Checksum | Fletcher checksum of the complete contents of the link state advertisement. |
Link count | Number of interfaces detected for router. |
The following is sample output from the show ip ospf database asb-summary command when no optional arguments are specified:
Router# show ip ospf database asb-summary
OSPF Router with id(190.20.239.66) (Process ID 300)
Displaying Summary ASB Link States(Area 0.0.0.0)
LS age: 1463
Options: (No TOS-capability)
LS Type: Summary Links(AS Boundary Router)
Link State ID: 155.187.245.1 (AS Boundary Router address)
Advertising Router: 155.187.241.5
LS Seq Number: 80000072
Checksum: 0x3548
Length: 28
Network Mask: 0.0.0.0 TOS: 0 Metric: 1
Table 29 describes significant fields shown in the display.
| Field | Description |
|---|---|
OSPF Router with id | Router ID number. |
Process ID | OSPF process ID. |
LS age | Link state age. |
Options | Type of service options (Type 0 only). |
LS Type | Link state type. |
Link State ID | Link state ID (autonomous system boundary router). |
Advertising Router | Advertising router's ID. |
LS Seq Number | Link state sequence (detects old or duplicate link state advertisements). |
Checksum | LS checksum (Fletcher checksum of the complete contents of the link state advertisement). |
Length | Length in bytes of the link state advertisement. |
Network Mask | Network mask implemented. |
TOS | Type of service. |
Metric | Link state metric. |
The following is sample output from the show ip ospf database external command when no optional arguments are specified:
Router# show ip ospf database external OSPF Router with id(190.20.239.66) (Autonomous system 300) Displaying AS External Link States LS age: 280 Options: (No TOS-capability) LS Type: AS External Link Link State ID: 143.105.0.0 (External Network Number) Advertising Router: 155.187.70.6 LS Seq Number: 80000AFD Checksum: 0xC3A Length: 36 Network Mask: 255.255.0.0 Metric Type: 2 (Larger than any link state path) TOS: 0 Metric: 1 Forward Address: 0.0.0.0 External Route Tag: 0
Table 30 describes significant fields shown in the display.
| Field | Description |
|---|---|
OSPF Router with id | Router ID number. |
Autonomous system | OSPF autonomous system number (OSPF process ID). |
LS age | Link state age. |
Options | Type of service options (Type 0 only). |
LS Type | Link state type. |
Link State ID | Link state ID (External Network Number). |
Advertising Router | Advertising router's ID. |
LS Seq Number | Link state sequence number (detects old or duplicate link state advertisements). |
Checksum | LS checksum (Fletcher checksum of the complete contents of the link state advertisement). |
Length | Length in bytes of the link state advertisement. |
Network Mask | Network mask implemented. |
Metric Type | External Type. |
TOS | Type of service. |
Metric | Link state metric. |
Forward Address | Forwarding address. Data traffic for the advertised destination will be forwarded to this address. If the forwarding address is set to 0.0.0.0, data traffic will be forwarded instead to the advertisement's originator. |
External Route Tag | External route tag, a 32-bit field attached to each external route. This is not used by the OSPF protocol itself. |
The following is sample output from the show ip ospf database network command when no optional arguments are specified:
Router# show ip ospf database network
OSPF Router with id(190.20.239.66) (Process ID 300)
Displaying Net Link States(Area 0.0.0.0)
LS age: 1367
Options: (No TOS-capability)
LS Type: Network Links
Link State ID: 155.187.1.3 (address of Designated Router)
Advertising Router: 190.20.239.66
LS Seq Number: 800000E7
Checksum: 0x1229
Length: 52
Network Mask: 255.255.255.0
Attached Router: 190.20.239.66
Attached Router: 155.187.241.5
Attached Router: 155.187.1.1
Attached Router: 155.187.54.5
Attached Router: 155.187.1.5
Table 31 describes significant fields shown in the display.
| Field | Description |
|---|---|
OSPF Router with id | Router ID number. |
Process ID 300 | OSPF process ID. |
LS age | Link state age. |
Options | Type of service options (Type 0 only). |
LS Type: | Link state type. |
Link State ID | Link state ID of designated router. |
Advertising Router | Advertising router's ID. |
LS Seq Number | Link state sequence (detects old or duplicate link state advertisements). |
Checksum | LS checksum (Fletcher checksum of the complete contents of the link state advertisement). |
Length | Length in bytes of the link state advertisement. |
Network Mask | Network mask implemented. |
AS Boundary Router | Definition of router type. |
Attached Router | List of routers attached to the network, by IP address. |
The following is sample output from the show ip ospf database router command when no optional arguments are specified:
Router# show ip ospf database router
OSPF Router with id(190.20.239.66) (Process ID 300)
Displaying Router Link States(Area 0.0.0.0)
LS age: 1176
Options: (No TOS-capability)
LS Type: Router Links
Link State ID: 155.187.21.6
Advertising Router: 155.187.21.6
LS Seq Number: 80002CF6
Checksum: 0x73B7
Length: 120
AS Boundary Router
155 Number of Links: 8
Link connected to: another Router (point-to-point)
(link ID) Neighboring Router ID: 155.187.21.5
(Link Data) Router Interface address: 155.187.21.6
Number of TOS metrics: 0
TOS 0 Metrics: 2
Table 32 describes significant fields shown in the display.
| Field | Description |
|---|---|
OSPF Router with id | Router ID number. |
Process ID | OSPF process ID. |
LS age | Link state age. |
Options | Type of service options (Type 0 only). |
LS Type | Link state type. |
Link State ID | Link state ID. |
Advertising Router | Advertising router's ID. |
LS Seq Number | Link state sequence (detects old or duplicate link state advertisements). |
Checksum | LS checksum (Fletcher checksum of the complete contents of the link state advertisement). |
Length | Length in bytes of the link state advertisement. |
AS Boundary Router | Definition of router type. |
Number of Links | Number of active links. |
link ID | Link type. |
Link Data | Router interface address. |
TOS | Type of service metric (Type 0 only). |
The following is sample output from show ip ospf database summary command when no optional arguments are specified:
Router# show ip ospf database summary
OSPF Router with id(190.20.239.66) (Process ID 300)
Displaying Summary Net Link States(Area 0.0.0.0)
LS age: 1401
Options: (No TOS-capability)
LS Type: Summary Links(Network)
Link State ID: 155.187.240.0 (summary Network Number)
Advertising Router: 155.187.241.5
LS Seq Number: 80000072
Checksum: 0x84FF
Length: 28
Network Mask: 255.255.255.0 TOS: 0 Metric: 1
Table 33 describes significant fields shown in the display.
| Field | Description |
|---|---|
OSPF Router with id | Router ID number. |
Process ID | OSPF process ID. |
LS age | Link state age. |
Options | Type of service options (Type 0 only). |
LS Type | Link state type. |
Link State ID | Link state ID (summary network number). |
Advertising Router | Advertising router's ID. |
LS Seq Number | Link state sequence (detects old or duplicate link state advertisements). |
Checksum | LS checksum (Fletcher checksum of the complete contents of the link state advertisement). |
Length | Length in bytes of the link state advertisement. |
Network Mask | Network mask implemented. |
TOS | Type of service. |
Metric | Link state metric. |
The following is sample output from show ip ospf database database-summary command when no optional arguments are specified:
Router# show ip ospf database database-summary OSPF Router with ID (172.19.65.21) (Process ID 1) Area ID Router Network Sum-Net Sum-ASBR Subtotal Delete Maxage 202 1 0 0 0 1 0 0 AS External 0 0 0 Total 1 0 0 0 1
Table 34 describes significant fields shown in the display.
| Field | Description |
|---|---|
Area ID | Area number. |
Router | Number of router link state advertisements in that area. |
Network | Number of network link state advertisements in that area. |
Sum-Net | Number of summary link state advertisements in that area. |
Sum-ASBR | Number of summary autonomous system boundary router (ASBR) link state advertisements in that area. |
Subtotal | Sum of Router, Network, Sum-Net, and Sum-ASBR for that area. |
Delete | Number of link state advertisements that are marked "Deleted" in that area. |
Maxage | Number of link state advertisements that are marked "Maxaged" in that area. |
AS External | Number of external link state advertisements. |
To display OSPF-related interface information, use the show ip ospf interface EXEC command.
show ip ospf interface [type number]
type | (Optional) Interface type. |
number | (Optional) Interface number. |
EXEC
This command first appeared in Cisco IOS Release 10.0.
The following is sample output of the show ip ospf interface command when Ethernet 0 is specified:
Router# show ip ospf interface ethernet 0 Ethernet 0 is up, line protocol is up Internet Address 131.119.254.202, Mask 255.255.255.0, Area 0.0.0.0 AS 201, Router ID 192.77.99.1, Network Type BROADCAST, Cost: 10 Transmit Delay is 1 sec, State OTHER, Priority 1 Designated Router id 131.119.254.10, Interface address 131.119.254.10 Backup Designated router id 131.119.254.28, Interface addr 131.119.254.28 Timer intervals configured, Hello 10, Dead 60, Wait 40, Retransmit 5 Hello due in 0:00:05 Neighbor Count is 8, Adjacent neighbor count is 2 Adjacent with neighbor 131.119.254.28 (Backup Designated Router) Adjacent with neighbor 131.119.254.10 (Designated Router)
Table 35 describes significant fields shown in the display.
| Field | Description |
|---|---|
Ethernet | Status of physical link and operational status of protocol. |
Internet Address | Interface IP address, subnet mask, and area address. |
AS | Autonomous system number (OSPF process ID), router ID, network type, link state cost. |
Transmit Delay | Transmit delay, interface state, and router priority. |
Designated Router | Designated router ID and respective interface IP address. |
Backup Designated router | Backup designated router ID and respective interface IP address. |
Timer intervals configured | Configuration of timer intervals. |
Hello | Number of seconds until next hello packet is sent out this interface. |
Neighbor Count | Count of network neighbors and list of adjacent neighbors. |
To display OSPF-neighbor information on a per-interface basis, use the show ip ospf neighbor EXEC command.
show ip ospf neighbor [type number] [neighbor-id] [detail]
type | (Optional) Interface type. |
number | (Optional) Interface number. |
neighbor-id | (Optional) Neighbor ID. |
detail | (Optional) Displays all neighbors given in detail (list all neighbors). |
EXEC
This command first appeared in Cisco IOS Release 10.0.
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 neighbor ID Pri State Dead Time Address Interface 199.199.199.137 1 FULL/DR 0:00:31 160.89.80.37 Ethernet0 192.31.48.1 1 FULL/DROTHER 0:00:33 192.31.48.1 Fddi0 192.31.48.200 1 FULL/DROTHER 0:00:33 192.31.48.200 Fddi0 199.199.199.137 5 FULL/DR 0:00:33 192.31.48.189 Fddi0
The following is sample output showing summary information about the neighbor that matches the neighbor ID:
Router# show ip ospf neighbor 199.199.199.137
Neighbor 199.199.199.137, interface address 160.89.80.37
In the area 0.0.0.0 via interface Ethernet0
Neighbor priority is 1, State is FULL
Options 2
Dead timer due in 0:00:32
Link State retransmission due in 0:00:04
Neighbor 199.199.199.137, interface address 192.31.48.189
In the area 0.0.0.0 via interface Fddi0
Neighbor priority is 5, State is FULL
Options 2
Dead timer due in 0:00:32
Link State retransmission due in 0:00:03
If 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 0 199.199.199.137
Neighbor 199.199.199.137, interface address 160.89.80.37
In the area 0.0.0.0 via interface Ethernet0
Neighbor priority is 1, State is FULL
Options 2
Dead timer due in 0:00:37
Link State retransmission due in 0:00:04
You 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 0 ID Pri State Dead Time Address Interface 192.31.48.1 1 FULL/DROTHER 0:00:33 192.31.48.1 Fddi0 192.31.48.200 1 FULL/DROTHER 0:00:32 192.31.48.200 Fddi0 199.199.199.137 5 FULL/DR 0:00:32 192.31.48.189 Fddi0
The following is sample output from the show ip ospf neighbor detail command:
Router# show ip ospf neighbor detail
Neighbor 160.89.96.54, interface address 160.89.96.54
In the area 0.0.0.3 via interface Ethernet0
Neighbor priority is 1, State is FULL
Options 2
Dead timer due in 0:00:38
Neighbor 160.89.103.52, interface address 160.89.103.52
In the area 0.0.0.0 via interface Serial0
Neighbor priority is 1, State is FULL
Options 2
Dead timer due in 0:00:31
Table 36 describes the fields shown in the displays.
| Field | Description |
|---|---|
Neighbor | Neighbor router ID. |
interface address | IP address of the interface. |
In the area | Area and interface through which OSPF neighbor is known. |
Neighbor priority | Router priority of neighbor, neighbor state. |
State | OSPF state. |
Options | Hello packet options field contents (E-bit only; possible values are 0 and 2; 2 indicates area is not a stub; 0 indicates area is a stub. |
Dead timer | Expected time before Cisco IOS software will declare neighbor dead. |
To display a list of all link state advertisements (LSAs) requested by a router, use the show ip ospf request-list EXEC command.
show ip ospf request-list [nbr] [intf] [intf-nbr]
nbr | (Optional) Neighbor. Displays the list of all LSAs requested by the router from this neighbor. |
intf | (Optional) Interface. Displays the list of all LSAs requested by the router from this interface. |
intf-nbr | (Optional) Displays the list of all LSAs waiting to be retransmitted on this interface, from this neighbor. |
EXEC
This command first appeared in Cisco IOS Release 10.2.
The following is sample output from the show ip ospf request-list command:
router# show ip ospf request-list se0
OSPF Router with ID (200.1.1.11) (Process ID 1)
Neighbor 200.1.1.12, interface Serial0 address 144.1.1.12
Type LS ID ADV RTR Seq NO Age Checksum
1 200.1.1.12 200.1.1.12 0x8000020D 8 0x6572
To display a list of all link state advertisements (LSAs) waiting to be retransmitted, use the show ip ospf retransmission-list EXEC command.
show ip ospf retransmission-list [nbr] [intf] [intf-nbr]
nbr | (Optional) Neighbor. Displays the list of all LSAs waiting to be retransmitted for this neighbor. |
intf | (Optional) Interface. Displays the list of all LSAs waiting to be transmitted on this interface. |
intf-nbr | (Optional) Displays the list of all LSAs waiting to be retransmitted on this interface, from this neighbor. |
EXEC
This command first appeared in Cisco IOS Release 10.2.
The following is sample output from the show ip ospf retransmission-list command:
Router# show ip ospf retransmission-list se0
OSPF Router with ID (200.1.1.12) (Process ID 1)
Neighbor 200.1.1.11, interface Serial0 address 144.1.1.11
Link state retransmission due in 3764 msec, Queue length 2
Type LS ID ADV RTR Seq NO Age Checksum
1 200.1.1.12 200.1.1.12 0x80000210 0 0xB196
To display a list of all summary address redistribution information configured under an OSPF process, use the show ip ospf summary-address EXEC command.
show ip ospf [process-id] summary-address
process-id | (Optional) OSPF area ID. |
EXEC
This command first appeared in Cisco IOS Release 10.0.
The process-id can be entered as a decimal number or as an IP address format.
The following is sample output from the show ip ospf summary-address command:
Router# show ip ospf summary-address OSPF Process 2, Summary-address 1.2.0.0/255.255.0.0 Metric -1, Type 0, Tag 0 1.2.0.0/255.255.0.0 Metric -1, Type 0, Tag 10
To display parameters about and the current state of OSPF virtual links, use the show ip ospf virtual-links EXEC command.
show ip ospf virtual-linksThis command has no arguments or keywords.
EXEC
This command first appeared in Cisco IOS Release 10.0.
The information displayed by the show ip ospf virtual-links command is useful in debugging OSPF routing operations.
The following is sample output from the show ip ospf virtual-links command:
Router# show ip ospf virtual-links Virtual Link to router 160.89.101.2 is up Transit area 0.0.0.1, via interface Ethernet0, Cost of using 10 Transmit Delay is 1 sec, State POINT_TO_POINT Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5 Hello due in 0:00:08 Adjacency State FULL
Table 37 describes significant fields shown in the display.
| Field | Description |
|---|---|
Virtual Link to router 160.89.101.2 is up | Specifies the OSPF neighbor, and if the link to that neighbor is up or down. |
Transit area 0.0.0.1 | The transit area through which the virtual link is formed. |
via interface Ethernet0 | The interface through which the virtual link is formed. |
Cost of using 10 | The cost of reaching the OSPF neighbor through the virtual link. |
Transmit Delay is 1 sec | The transmit delay on the virtual link. |
State POINT_TO_POINT | The state of the OSPF neighbor. |
Timer intervals... | The various timer intervals configured for the link. |
Hello due in 0:00:08 | When the next hello is expected from the neighbor. |
Adjacency State FULL | The adjacency state between the neighbors. |
Use the summary-address router configuration command to create aggregate addresses for OSPF. The no summary-address command restores the default.
summary-address address mask {level-1 | level-1-2 | level-2} prefix mask [not-advertise]
address | Summary address designated for a range of addresses. |
mask | IP subnet mask used for the summary route. |
level-1 | Only routes redistributed into Level 1 are summarized with the configured address/mask value. This keyword applies to IS-IS only. |
level-1-2 | The summary router is injected into both a Level 1 area and a Level 2 subdomain. This keyword applies to IS-IS only. |
level-2 | Routes learned by Level 1 routing will be summarized into the Level 2 backbone with the configured address/mask value. This keyword applies to IS-IS only. |
prefix | IP route prefix for the destination. |
mask | IP subnet mask used for the summary route. |
not-advertise | (Optional) Used to suppress routes that match the prefix/mask pair. This keyword applies to OSPF only. |
tag tag | (Optional) Tag value that can be used as a "match" value for controlling redistribution via route maps. This keyword applies to OSPF only. |
Disabled
Router configuration
This command first appeared in Cisco IOS Release 10.0.
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.
In the following example, summary address 10.1.0.0 includes address 10.1.1.0, 10.1.2.0, 10.1.3.0, and so forth. Only the address 10.1.0.0 is advertised in an external link state advertisement.
summary-address 10.1.0.0 255.255.0.0
You can use the master indexes or search online to find documentation of related commands.
area range
ip ospf authentication-key
ip ospf message-digest-key
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 router configuration command. To return to the default timer values, use the no form of this command.
timers spf spf-delay spf-holdtime
spf-delay | Delay time, in seconds, between when OSPF receives a topology change and when it starts a SPF. calculation. It can be an integer from 0 to 65535. The default time is 5 seconds. A value of 0 means that there is no delay; that is, the SPF calculation is started immediately. |
spf-holdtime | Minimum time, in seconds, between two consecutive SPF calculations. It can be an integer from 0 to 65535. The default time is 10 seconds. A value of 0 means that there is no delay; that is, two consecutive SPF calculations can be done one immediately after the other. |
spf-delay: 5 seconds
spf-holdtime: 10 seconds
Router configuration
This command first appeared in Cisco IOS Release 10.3.
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 consumes more CPU processing time.
The following example changes the delay to 10 seconds and the hold time to 20 seconds:
timers spf 10 20
Posted: Wed Sep 20 16:03:56 PDT 2000
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