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ip ospf message-digest-key md5
neighbor database-filter all out
nsf ietf helper strict-lsa-checking
ip 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 [disable]
no ip ospf flood-reduction
Syntax Description
disable
(Optional) Disables the suppressing of unnecessary flooding of LSAs in stable topologies.
Note
This keyword is available only in virtual network interface mode.
Defaults
This command is disabled by default.
Command Modes
Interface configuration (config-if)
Virtual network interface (config-if-vnet)Command History
Usage Guidelines
All routers supporting the Open Shortest Path First (OSPF) demand circuit are compatible and can interact with routers supporting flooding reduction.
If the ip ospf flood-reduction command is enabled for a virtual network and you want to disable it, use the disable keyword in virtual network interface configuration mode.
Examples
The following example reduces the flooding of unnecessary LSAs on serial interface 0:
interface serial 0ip ospf flood-reductionRelated Commands
show ip ospf interface
Displays OSPF-related interface information.
show ip ospf neighbor
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. The range is from 1 to 65535.
Defaults
10 seconds (Ethernet)
30 seconds (nonbroadcast)
Command Modes
Interface configuration (config-if)
Virtual network interface (config-if-vnet)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
ip ospf dead-interval
Sets the time period for which hello packets must not have been seen before neighbors declare the router down.
ip ospf lls
To enable Link-Local Signaling (LLS) on an interface, regardless of the router-level LLS setting, use the ip ospf lls command in interface configuration mode. To reconfigure the router-level LLS setting on the specific interface, use the no or default version of this command.
ip ospf lls [disable]
{no | default} ip ospf lls [disable]
Syntax Description
Defaults
LLS is enabled.
Command Modes
Interface configuration (config-if)
Virtual network interface (config-if-vnet)Command History
Usage Guidelines
By default, each Open Shortest Path First (OSPF) interface inherits the LLS setting from the router level. The ip ospf lls interface-level command takes precedence over the capability lls router-level command. For example, if you have entered the no capability lls command to disable LLS at the router level, you can use the ip ospf lls command to selectively enable LLS for specific interfaces, in order to allow the router to enable OSPF nonstop forwarding (NSF) awareness only for these specified interfaces.
To unconfigure the interface LLS setting, enter either the default ip ospf lls command or the no ip ospf lls command to restore the default LLS setting for the interface that has been configured at the router level. For example, if the capability lls command is enabled (by default) at the router level, you can use either the default ip ospf lls command or the no ip ospf lls command to disable LLS on specific interfaces, for instance, to interoperate on network segments where there are routers that do not properly handle LLS.
Note
Examples
In following example, LLS is disabled on Ethernet interface 2/0:
Router(config)# interface Ethernet2/0Router(config-if)# ip address 10.1.145.2 255.255.0.0Router(config-if)# no ip directed-broadcastRouter(config-if)# ip ospf message-digest-key 1 md5 testingRouter(config-if)# ip ospf lls disableRelated Commands
ip ospf message-digest-key md5
To enable Open Shortest Path First (OSPF) Message Digest 5 (MD5) authentication, use the ip ospf message-digest-key md5 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 encryption-type md5 key
no ip ospf message-digest-key key-id
Syntax Description
Defaults
OSPF MD5 authentication is disabled.
Command Modes
Interface configuration (config-if)
Virtual network interface (config-if-vnet)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
ip ospf mtu-ignore
To disable Open Shortest Path First (OSPF) maximum transmission unit (MTU) mismatch detection on receiving Database Descriptor (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 [disable]
no ip ospf mtu-ignore
Syntax Description
disable
(Optional) Causes OSPF MTU mismatch detection to occur (because ignoring OSPF MTU mismatch detection is being disabled).
Note
Defaults
OSPF MTU mismatch detection is enabled.
Command Modes
Interface configuration (config-if)
Virtual network interface (config-if-vnet)Command History
Usage Guidelines
OSPF checks whether neighbors are using the same MTU on a common interface. This check is performed when neighbors exchange 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.
If the ip ospf mtu-ignore command is enabled for a virtual network and you want to disable it, use the disable keyword in virtual network interface configuration mode.
Examples
The following example disables MTU mismatch detection on receiving DBD packets:
interface serial 0/0ip ospf mtu-ignoreip ospf name-lookup
To configure Open Shortest Path First (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 Open Shortest Path First (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 (config-if)
Virtual network interface (config-if-vnet)Command History
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:
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Examples
The following example sets your OSPF network as a broadcast network:
interface serial 0ip address 192.168.77.17 255.255.255.0ip 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 prefix-suppression
To prevent Open Shortest Path First (OSPF) from advertising all IP prefixes that belong to a specific interface, except for prefixes that are associated with secondary IP addresses, use the ip ospf prefix-suppression command in interface configuration mode. To remove the per-interface configuration from the interface and allow the interface to inherit the IP prefix suppression setting from the router configuration, use the no form of this command.
ip ospf prefix-suppression [disable]
no ip ospf prefix-suppression
Syntax Description
disable
(Optional) Specifies that OSPF will advertise the interface IP prefix, regardless of the router mode configuration for IP prefix suppression.
Command Default
All IP prefixes that are associated with the interface are advertised.
Command Modes
Interface configuration (config-if)
Command History
12.4(15)T
This command was introduced.
Cisco IOS XE Release 2.6
This command was integrated into Cisco IOS XE Release 2.6
Usage Guidelines
You can suppress IP prefixes on a per-interface basis for all interface types by entering the ip ospf prefix-suppression command in interface configuration mode.
When the ip ospf prefix-suppression command is configured, it takes precedence over the prefix-suppression router configuration command. If the prefix-suppression router configuration command has been entered, the interfaces for the specified OSPF process will inherit the prefix suppression setting from the router configuration command.
When you enter the ip ospf prefix-suppression command, prefix generation for any interface type, including loopbacks and passive interfaces, is suppressed. Only prefixes associated with secondary IP addressees remain unaffected.
Examples
The following example suppresses all IP prefixes, except for those associated with secondary IP addresses, for GigabitEthernet interface 1/1/1:
interface gigabitethernet 1/1/1ip ospf prefix-suppressionRelated 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
Syntax Description
Command Default
Priority of 1
Command Modes
Interface configuration (config-if)
Virtual network interface (config-if-vnet)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 Open Shortest Path First (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
ip ospf resync-timeout
To configure how long the router will wait before taking a neighbor adjacency down if the out-of-band resynchronization (oob-resync) has not taken place since the time a restart signal (Open Shortest Path First [OSPF] hello packet with RS-bit set) was received from the neighbor, use the ip ospf resync-timeout command in interface configuration mode. To restore the default value, use the no form of this command.
ip ospf resync-timeout seconds
no ip ospf resync-timeout
Syntax Description
Command Default
The default value is 40 seconds or the value set for the interface's OSPF dead interval, whichever is greater.
Command Modes
Interface configuration
Command History
Usage Guidelines
When an OSPF nonstop forwarding (NSF) router performs a route processor (RP) switchover, it notifies its neighbors, via a special hello packet, of such action and requests that each neighbor help resynchronize the Link State Database.
When a neighbor (that is NSF-aware) receives the special hello packet from the NSF-capable router, it starts a resync timeout timer and waits to synchronize its database with the NSF-capable router. If the NSF-capable router does not initiate the database resynchronization process before the resync-timeout timer expires, the NSF-aware neighbor will take down the adjacency with the NSF-capable router.
By default, the resync-timeout timer is set to 40 seconds or the dead interval of the interface, whichever is greater. (By default, the dead interval is 4 times the hello interval; the hello interval defaults to 10 seconds for Ethernet or 30 seconds for nonbroadcast.) The ip ospf resync-timeout command allows the resync-timeout to be changed and independent of the dead interval or default value.
Examples
This example sets the OSPF resync-timeout interval to 50 seconds:
interface GigabitEthernet 6/0/0ip ospf resync-timeout 50Related Commands
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
seconds
Time (in seconds) between retransmissions. The range is from 1 to 65535 seconds. The default is 5 seconds.
Defaults
5 seconds
Command Modes
Interface configuration (config-if)
Virtual network interface (config-if-vnet)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 the seconds argument should be greater than the expected round-trip delay between any two routers on the attached network. The setting of this parameter should also be conservative, or needless LSA retransmissions may occur. The value should be larger for serial lines and virtual links.
Note
Examples
The following example sets the retransmit interval value to 8 seconds:
interface ethernet 2ip ospf retransmit-interval 8ip ospf shutdown
To initiate an Open Shortest Path First (OSPF) protocol graceful shutdown at the interface level, use the ip ospf shutdown command in interface configuration mode. To restart the OSPF protocol on an interface, use the no form of this command.
ip ospf shutdown [disable]
no ip ospf shutdown
Syntax Description
Command Default
OSPF stays active at the interface level.
Command Modes
Interface configuration (config-if)
Virtual network interface (config-if-vnet)Command History
Usage Guidelines
Use the ip ospf shutdown command to put OSPF in shutdown mode under a specific interface.
If the ip ospf shutdown command is enabled for a virtual network and you want to disable it, use the disable keyword in virtual network interface configuration mode.
Examples
The following example shows how to initiate a graceful shutdown of the OSPF protocol on Ethernet interface 0/2:
Router(config)# interface ethernet 0/2Router(config-if)# ip ospf shutdownRelated Commands
shutdown (router ospf)
Initiates a graceful shutdown of the OSPF protocol under the current instance.
ip 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 (config-if)
Virtual network interface (config-if-vnet)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 3ip ospf ttl-security
To configure the Time-to-Live (TTL) security check feature on a specific interface, use the ip ospf ttl-security command in interface configuration mode. To disable TTL security on an interface, use the no form of this command.
ip ospf ttl-security [hops hop-count | disable]
no ip ospf ttl-security
Syntax Description
hops hop-count
(Optional) Configures the maximum number of IP hops. The hop-count argument range is from 1 to 254.
disable
(Optional) Disables TTL security on an interface.
Command Default
TTL security is disabled on all Open Shortest Path First (OSPF) interfaces.
Command Modes
Interface configuration (config-if)
Virtual network interface (config-if-vnet)Command History
Usage Guidelines
Use the ip ospf ttl-security command to configure TTL security on a specific interface.
The disable keyword can be used to disable TTL security on a specific interface but is only useful if the ttl-security all-interfaces command was used in router mode to first configure TTL security on all OSPF interfaces. In this way, all OSPF interfaces can be configured with TTL security and then individual interfaces can be disabled. This can save time as opposed to configuring each interface one-by-one from the start.
Examples
The following example shows how to effectively use the disable keyword to disable TTL security on Ethernet interface 0/0 after the feature has first been configured on all OSPF interfaces:
Router# configure terminalRouter(config)# router ospf 1Router(config-router)# ttl-security all-interfacesRouter(config-router)# exitRouter(config)# interface ethernet 0/0Router(config-if)# ip ospf ttl-security disableRelated Commands
ttl-security all-interfaces
Configures TTL security check on all OSPF interfaces.
limit retransmissions
To change or remove the limit in the number of retransmissions of database exchange and update packets for both demand and non-demand circuits, use the limit retransmissions command in router configuration mode. To reset the maximum number of retransmissions back to the default value of 24, use the no form of this command.
limit retransmissions [dc {max-number | disable}] [non-dc {max-number | disable}]
no limit transmissions [dc | non-dc]
Syntax Description
Defaults
Maximum number of retransmissions is 24.
Command Modes
Router configuration
Command History
Usage Guidelines
Cisco IOS Release 12.2(4)T added a limit to the number of retransmissions of database exchange and update packets for both demand and nondemand circuits. The retransmission of these packets stops once this retry limit is reached, thus preventing unnecessary use of the link in continual retransmission of the packets if, for some reason, a neighbor is not responding during adjacency forming.
The limit for both demand circuit and nondemand circuit retransmissions is 24.
The limit-retransmissions command allows you to either remove (disable) the limit or change the maximum number of retransmissions to be a number from 1 to 255. The configuration of this command provides for backward compatibility for previous or other releases of Cisco IOS Software or other routers that do not have this feature.
Note
Examples
The following example shows how to set the maximum number of demand circuit retransmissions to 10:
limit retransmissions dc 10The following example shows how to remove the limit for the number of demand circuit retransmissions:
limit retransmissions dc disableThe following example shows how to set the maximum number of demand circuit retransmissions to 10 and to set the maximum number of nondemand circuit retransmissions to 20:
limit retransmissions dc 10 non-dc 20The following example shows how to set the maximum number of demand circuit retransmissions to 10, and to remove the limit for the number of nondemand circuit retransmissions:
limit retransmissions dc 10 non-dc disableThe following example shows how to reset both the demand circuit and nondemand circuit maximum number of retransmissions back to the default of 24:
no limit retransmissionsRelated Commands
local-rib-criteria
To specify that the OSPF local Routing Information Base (RIB) will be used for route validation, use the local-rib-criteria command in router configuration mode. To remove local RIB route validation, use the no form of this command.
local-rib-criteria [forwarding-address] [inter-area-summary] [nssa-translation]
no local-rib-criteria [forwarding-address] [inter-area-summary] [nssa-translation]
Syntax Description
Command Default
The global RIB (not the local RIB) is used for route validation.
Command Modes
Router configuration (config-router)
Command History
Usage Guidelines
If the local-rib-criteria is command is entered without any optional keywords, the local RIB will be used as criteria for all of the options (forwarding address, inter-area summary, and NSSA translation).
You can enter the local-rib-criteria command with one or more of the optional keywords to configure the OSPF routing process to use the local RIB only for forwarding address, inter-area-summary, or NSSA translation route generation.
Note
Note
Examples
The following example specifies that the local RIB should be used as the criteria for NSSA translation:
router ospf 23local-rib-criteria nssa-translationThe following example enables all local RIB criteria options:
router ospf 1
local-rib-criteria
The following example specifies that the local RIB will be used only for inter-area summary route generation:
router ospf 1
local-rib-criteria inter-area-summary
log-adjacency-changes
To configure the router to send a syslog message when an Open Shortest Path First (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.
Command Default
Enabled
Command Modes
Router configuration
Command History
Usage Guidelines
This command allows you to know about OSPF neighbors going up or down without turning on the debug ip ospf packet command or the debug ipv6 ospf adjacency command. The log-adjacency-changes command provides a higher level view of those changes of the peer relationship with less output than the debug command provides. The log-adjacency-changes command is on by default but only up/down (full/down) events are reported, unless the detail keyword is also used.
Examples
The following example configures the router to send a syslog message when an OSPF neighbor state changes:
log-adjacency-changes detailRelated Commands
debug ip ospf packet
Displays information about each OSPF packet received for IPv4.
debug ipv6 ospf
Displays debugging information for OSPF for IPv6.
max-lsa
To limit the number of nonself-generated link-state advertisements (LSAs) that an Open Shortest Path First (OSPF) routing process can keep in the OSPF link-state database (LSDB), use the max-lsa command in router configuration mode. To remove the limit of non self-generated LSAs that an OSPF routing process can keep in the OSPF LSDB, use the no form of this command.
max-lsa maximum-number [threshold-percentage] [warning-only] [ignore-time minutes] [ignore-count count-number] [reset-time minutes]
no max-lsa maximum-number [threshold-percentage] [warning-only] [ignore-time minutes] [ignore-count count-number] [reset-time minutes]
Syntax Description
Defaults
The number of nonself-generated LSAs that an OSPF routing process can keep in the OSPF LSDB is not limited.
threshold-percentage: 75 percent
warning-only warning message: disabled
ignore-time minutes: 5 minutes
ignore-count count-number: 5 times
reset-time minutes: 10 minutesCommand Modes
Router configuration
Command History
Usage Guidelines
To prevent the OSPF process from endlessly changing from the normal state of operation to the ignore state as a result of the LSA count exceeding the maximum configured number immediately after it returns from the ignore state to the normal state of operation, the OSPF process keeps a counter on how many times the process went into the ignore state. This counter is called the ignore count. If the ignore count exceeds the maximum number of LSAs that is specified by the ignore-count keyword and counter-number argument, the OSPF process remains in the ignore state permanently. To return the OSPF process to the state of normal operation, enter the clear ip ospf command.
If the router is placed into a permanent ignore state, we recommend that you identify and correct the cause of the problem involving the router that is generating the LSAs, or, if possible, increase the limit that has been configured by the max-lsa command before you try to bring the router back into normal operation.
If the router that has generated large numbers of LSAs is not reachable, these LSAs cannot be removed from the OSPF area and domain. As a result, any other router leaving the ignore state and returning to normal operation may reach the ignore state again. We recommend that you take one of the following actions in order to bring the router back into the network:
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When the warning-only keyword is used, the OSPF process never enters the ignore state. When the LSA count exceeds the maximum limit that is specified by the maximum-number argument, only an error message is logged and the OSPF process continues in its normal operation.
When the max-lsa command is entered for the first time or when any of the parameters of the command are changed, the OSPF process undergoes a soft-reset procedure.
Examples
The following example sets a limit of 12,000 LSAs that can be received before the OSPF process enters the ignore state:
Router(config)# router ospf 100Router(config-router)# router-id 209.165.201.0Router(config-router)# log-adjacency-changesRouter(config-router)# max-lsa 12000Router(config-router)# network 209.165.201.1 255.255.255.255In the following example, an OSPF process has remained in the ignore state permanently. When the clear ip ospf command is entered the OSPF process returns to the state of normal operation and clears redistribution based on the OSPF routing process ID.
Router(config-router)# clear ip ospf 100 processRelated Commands
max-metric router-lsa
To configure a router that is running the Open Shortest Path First (OSPF) protocol to advertise a maximum metric so that other routers do not prefer the router as an intermediate hop in their shortest path first (SPF) calculations, use the max-metric router-lsa command in router address family topology or router configuration mode. To disable the advertisement of a maximum metric, use the no form of this command.
max-metric router-lsa [external-lsa [max-metric-value]] [include-stub] [on-startup {seconds | wait-for-bgp}] [summary-lsa [max-metric-value]]
no max-metric router-lsa [external-lsa [max-metric-value]] [include-stub] [on-startup {seconds | wait-for-bgp}] [summary-lsa [max-metric-value]]
Syntax Description
Command Default
Router link-state advertisements (LSAs) are originated with normal link metrics.
Command Modes
Router address family topology configuration (config-router-af-topology)
Router configuration (config-router)Command History
Usage Guidelines
Enabling the max-metric router-lsa command will cause a router to originate LSAs with a maximum metric (LSInfinity: 0xFFFF) through all nonstub links, which allows BGP routing tables to converge without attracting transit traffic (if there are not alternate lower cost paths around the router). The router will advertise accurate (normal) metrics after the configured or default timers expire or after BGP sends a notification that routing tables have converged.
Note
The max-metric router-lsa command is useful in the following situations:
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Note
Note
Release 12.2(33)SRB
If you plan to configure the Multi-Topology Routing (MTR) feature, you need to enter the max-metric router-lsa command in router address family topology configuration mode in order for this OSPF router configuration command to become topology-aware.
Examples
The following example configures a router that is running OSPF to advertise a maximum metric for 100 seconds:
Router(config)# router ospf 100Router(config-router)# max-metric router-lsa on-startup 100The following example configures a router to advertise a maximum metric until BGP routing tables converge or until the default timer expires (600 seconds):
Router(config)# router ospf 100Router(config-router)# max-metric router-lsa on-startup wait-for-bgpThe following example configures a router that is running OSPF to advertise a maximum metric, which causes neighbor routers to select alternate paths for transit traffic before the router shuts down:
Router(config)# router ospf 100Router(config-router)# max-metric router-lsaRouter(config-router)# endThe following example configures stub links to be advertised with the maximum-metric in routers LSAs.
Router(config)# router ospf 1Router(config-router)# router-id 10.1.1.1Router(config-router)# max-metric router-lsa include-stubRouter(config-router)# endEntering the show ip ospf max-metric command with the include-stub keyword displays output that confirms that stub links are advertised with the maximum metric.
Router# show ip ospf max-metricRouting Process "ospf 1" with ID 10.1.1.1Start time: 00:00:03.524, Time elapsed: 01:02:28.292Originating router-LSAs with maximum metricCondition: always, State: activeAdvertise stub links with maximum metric in router-LSAsRelated Commands
show ip ospf
Displays general information about OSPF routing processes.
show ip ospf database
Displays lists of information related to the OSPF database for a specific router.
neighbor (OSPF)
To configure Open Shortest Path First (OSPF) routers interconnecting to nonbroadcast networks, use the neighbor command in router address family topology or 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
Command Default
This command is disabled by default. No configuration is specified.
Command Modes
Router address family topology configuration (config-router-af-topology)
Router configuration (config-router)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.
Release 12.2(33)SRB
If you plan to configure the Multi-Topology Routing (MTR) feature, you need to enter the neighbor command in router address family topology configuration mode in order for this OSPF router configuration command to become topology-aware.
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
ip ospf priority
Sets the router priority, which helps determine the designated router for this network.
neighbor database-filter all out
To filter outgoing link-state advertisements (LSAs) to an Open Shortest Path First (OSPF) neighbor, use the neighbor database-filter all out 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 [cost metric]
no neighbor ip-address database-filter all out
Syntax Description
ip-address
IP address of the neighbor to which outgoing LSAs are blocked.
cost metric
(Optional) Cost metric configured for the specified neighbor. The range of this value is from 0 to 65535.
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 all outcommand 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 Open Shortest Path First (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 ip-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 192.168.129.16 0.0.0.3 area 20network 192.168.129.40 0.0.0.3 area 20network 192.168.129.44 0.0.0.3 area 20network 192.168.129.96 0.0.0.3 area 20network 192.168.128.0 0.0.127.255 area 20!Enter the following:
no network 192.168.129.40 0.0.0.3 area 20Interfaces falling into the network range 192.168.129.40/0.0.0.3 will still remain active because the superset, 192.168.128.0/0.0.127.255, 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 192.168.128.0 0.0.127.255 area 20!If the following network statement is entered:
network 192.168.129.96 0.0.0.3 area 40then interfaces belonging to range 192.168.129.96/0.0.0.3, 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 192.168.129.40/0.0.0.3 to move from area 20 to area 40:
network 192.168.129.40 0.0.0.3 area 20network 192.168.129.40 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
nsf (OSPF)
Note
To configure Cisco nonstop forwarding (NSF) operations for Open Shortest Path First (OSPF), use the nsf command in router configuration mode. To disable Cisco NSF for OSPF, use the no form of this command.
nsf [enforce global]
no nsf [enforce global]
Syntax Description
enforce global
(Optional) Cancels NSF restart when non-NSF-aware neighboring networking devices are detected.
Command Default
This command is disabled by default; therefore, NSF operations for OSPF is not configured.
Command Modes
Router configuration
Command History
Usage Guidelines
The user must configure NSF operation for OSPF only if a router is expected to perform NSF during restart. For users to have full NSF benefits, all OSPF neighbors of the specified router must be NSF-aware.
If neighbors that are not NSF-aware are detected on a network interface, NSF restart is aborted on the interface; however, NSF restart will continue on other interfaces. This functionality applies to the default NSF mode of operation when NSF is configured.
If the user configures the optional enforce global keywords, NSF restart will be canceled for the entire process when neighbors that are not NSF-aware are detected on any network interface during restart. NSF restart will also be canceled for the entire process if a neighbor adjacency reset is detected on any interface or if an OSPF interface goes down. To revert to the default NSF mode, enter the no nsf enforce global command.
Examples
The following example enters router configuration mode and cancels the NSF restart for the entire OSPF process if neighbors that are not NSF-aware are detected on any network interface during restart:
Router(config)# router ospf 1Router(config-router)# nsf enforce globalRelated Commands
debug ip ospf nsf
Displays debugging messages related to OSPF NSF commands.
router ospf
Enables OSPF routing and places the router in router configuration mode.
nsf cisco
To enable Cisco nonstop forwarding (NSF) operations on a router that is running Open Shortest Path First (OSPF), use the nsf cisco command in router configuration mode. To disable Cisco NSF, use the no form of this command.
nsf cisco [enforce global]
no nsf cisco [enforce global]
Syntax Description
enforce global
(Optional) Cancels NSF restart when non-NSF-aware neighboring networking devices are detected.
Command Default
This command is disabled by default; therefore, Cisco NSF operations are disabled on a router that is running OSPF.
Command Modes
Router configuration
Command History
Usage Guidelines
For Cisco IOS Release 12.0(32)S and later releases, the nsf cisco [enforce global] command replaces the nsf [enforce global] command for OSPF.
To enable Cisco NSF on an OSPF router, you need to enter the nsf cisco command. When a router has Cisco NSF enabled, the router is said to be NSF-capable and will operate in graceful restart mode—the OSPF router process performs non-stop forwarding recovery due to a Route Processor (RP) switchover. By default, the neighbor routers of the NSF-capable router will be NSF-aware and will operate in NSF helper mode. When the NSF-capable router is performing graceful restart, the neighbor router helps with the non-stop forwarding recovery.
During the NSF restart process, if neighbors that are not NSF-aware are detected on a network interface, NSF restart is aborted on the interface; however, NSF restart will continue on other interfaces. This functionality applies to the default NSF mode of operation when Cisco NSF is configured. If the user configures the nsf cisco command with the optional enforce global keywords, NSF restart will be canceled for the entire process when neighbors that are not NSF-aware are detected on any network interface during restart. The NSF restart will also be canceled for the entire process when a neighbor adjacency reset is detected on any interface or when an OSPF interface goes down. To revert to the default NSF behavior, enter the no nsf cisco enforce global command.
Examples
The following example enables Cisco NSF on a router and causes the NSF restart to be canceled for the entire OSPF process if neighbors that are not NSF-aware are detected on any network interface during the restart.
router ospf 24nsf cisco enforce globalRelated Commands
nsf cisco helper disable
To disable Cisco nonstop forwarding (NSF) helper mode on a Cisco router that is running Open Shortest Path First (OSPF), use the nsf cisco helper disable command in router configuration mode. To reenable Cisco NSF helper mode, use the no form of this command.
nsf cisco helper disable
no nsf cisco helper disable
Syntax Description
This command has no arguments or keywords.
Command Default
This command is enabled by default; therefore, NSF helper mode is disabled on a Cisco router that is running OSPF.
Command Modes
Router configuration (config-router)
Command History
Usage Guidelines
When a router in an OSPF process has NSF enabled, the router is said to be NSF-capable and will operate in graceful restart mode—the OSPF router process performs nonstop forwarding recovery due to a Route Processor (RP) switchover. By default, the neighboring routers of the NSF-capable router will be NSF-aware and will operate in NSF helper mode. When the NSF-capable router is performing graceful restart, the helper routers assist in the nonstop forwarding recovery process. If you do not want the router to help the restarting neighbor with nonstop forwarding recovery, enter the nsf cisco helper disable command.
Examples
The following example disables NSF helper mode for the Cisco router on OSPF process 3:
router ospf 3nsf cisco helper disableRelated Commands
nsf ietf
To enable IETF nonstop forwarding (NSF) operations on a router that is running Open Shortest Path First (OSPF), use the nsf ietf command in router configuration mode. To disable IETF NSF, use the no form of this command.
nsf ietf [restart-interval seconds]
no nsf ietf [restart-interval seconds]
Syntax Description
restart-interval seconds
(Optional) Specifies length of the graceful restart interval, in seconds. The range is from 1 to 1800. The default is 120.
Command Default
This command is disabled by default; therefore, IETF NSF operations are disabled on a router that is running OSPF.
Command Modes
Router configuration
Command History
Usage Guidelines
To enable IETF NSF on an OSPF router, enter the nsf ietf command. When a router has NSF enabled, the router is said to be NSF-capable and will operate in graceful restart mode—the OSPF router process performs nonstop forwarding recovery due to a Route Processor (RP) switchover. By default, the neighbor routers of the NSF-capable router will be NSF-aware and will operate in NSF helper mode. When the NSF-capable router is performing graceful restart, the neighbor router helps in the nonstop forwarding recovery.
Examples
The following example enables IETF NSF (graceful restart) on a router, changing the graceful restart interval to 200 seconds:
router ospf 24nsf ietf restart-interval 200Related Commands
nsf ietf helper disable
To disable Internet Engineering Task Force (IETF) nonstop forwarding (NSF) helper mode on a router that is running Open Shortest Path First (OSPF), use the nsf ietf helper disable command in router configuration mode. To reenable IETF NSF helper mode, use the no form of this command.
nsf ietf helper disable
no nsf ietf helper disable
Syntax Description
This command has no arguments or keywords.
Command Default
This command is disabled by default; therefore, IETF NSF helper mode is enabled on a router that is running OSPF.
Command Modes
Router configuration (config-router)
Command History
Usage Guidelines
When a router in an OSPF process has NSF enabled, the router is said to be NSF-capable and will operate in graceful restart mode—the OSPF router process performs nonstop forwarding recovery due to a Route Processor (RP) switchover. By default, the neighboring routers of the NSF-capable router will be NSF-aware and will operate in NSF helper mode. When the NSF-capable router is performing graceful restart, the helper routers assist in the nonstop forwarding recovery process. If you do not want the router to help the restarting neighbor with nonstop forwarding recovery, enter the nsf ietf helper disable command.
Examples
The following example disables IETF NSF helper mode on a router on OSPF process 4:
router ospf 4nsf ietf helper disableRelated Commands
nsf ietf helper strict-lsa-checking
To enable strict link-state advertisement (LSA) checking on routers in an Open Shortest Path First (OSPF) process, use the nsf ietf helper strict-lsa-checking command in router configuration mode. To disable strict LSA checking, use the no form of this command.
nsf ietf helper strict-lsa-checking
no nsf ietf helper strict-lsa-checking
Syntax Description
This command has no arguments or keywords.
Command Default
This command is disabled by default; therefore, strict LSA checking is not done on routers in an OSPF process.
Command Modes
Router configuration (config-router)
Command History
Usage Guidelines
To enable strict LSA checking on both NSF-aware and NSF-capable routers, enter the nsf ietf helper strict-lsa-checking command. However, strict LSA checking will not become effective until the router becomes a helper router during an IETF graceful restart process. With strict LSA checking enabled, the helper router will terminate the helping process of the restarting router if it detects that there is a change to an LSA that would be flooded to the restarting router or if there is a changed LSA on the retransmission list of the restarting router when the graceful restart process is initiated.
Examples
The following example enables strict LSA checking on a router on OSPF process 12:
router ospf 12nsf ietf helper strict-lsa-checkingRelated Commands
nsr
To enable nonstop routing (NSR) operations on a router that is running Open Shortest Path First (OSPF), use the nsr command in router configuration mode. To disable NSR and return to the default, use the no form of this command.
nsr
no nsr
Syntax Description
This command has no arguments or keywords.
Command Default
NSR is disabled.
Command Modes
Router configuration (config-router)
Command History
15.1(2)S
This command was introduced.
Cisco IOS XE Release 3.3S
This command was integrated into Cisco IOS XE Release 3.3S.
Usage Guidelines
This command enables NSR on an OSPF router. With NSR enabled, a router with redundant Route Processors (RPs) is allowed to maintain its OSPF state and adjacencies across planned and RP switchovers. It does this by checkpointing state information from OSPF on the active RP to the standby RP. Later, following a switchover to the standby RP, OSPF can use this checkpointed information to continue operation without interruption.
This command is present only in images for platforms that have a hardware or software redundancy capability.
Examples
The following example enables NSR on an OSPF router:
Router> enableRouter# configure terminalRouter(config)# router ospf 1Router(config-router)# nsrRelated Commands
prefix-suppression
To prevent Open Shortest Path First (OSPF) from advertising all IP prefixes except prefixes that are associated with loopbacks, secondary IP addresses, and passive interfaces for a specific OSPF process, use the prefix-suppression command in router configuration mode. To advertise all IP prefixes, use the no form of this command.
prefix-suppression
no prefix-suppression
Syntax Description
This command has no arguments or keywords.
Command Default
All IP prefixes are advertised.
Command Modes
Router configuration (config-router)
Command History
12.4(15)T
This command was introduced.
Cisco IOS XE Release 2.6
This command was integrated into Cisco IOS XE Release 2.6
Usage Guidelines
You can globally suppress all IP prefixes (except prefixes that are associated with loopbacks, secondary IP addresses, and passive interfaces) for an entire OSPF process by using the prefix-suppression command in router configuration mode. You can also suppress IP prefixes on a per-interface basis by using the ip ospf prefix-suppression command in interface configuration mode. When the ip ospf prefix-suppression command is configured, it takes precedence over the prefix-suppression router configuration command.
Examples
The following example globally suppresses all IP prefixes except prefixes that are associated with loopbacks, secondary IP addresses, and passive interfaces for OSPF process 4:
router ospf 4prefix-suppressionRelated Commands
process-min-time percent
Note
To specify the minimum percentage of CPU process time OSPF takes before the CPU should yield to a process with a higher priority, use the process-min-time percent command in router configuration mode. To disable this function, use the no form of this command.
process-min-time percent percentage
no process-min-time percent
Syntax Description
percentage
Percentage of CPU process time to be used before trying to release the CPU for other processes. The valid value range is from 1 to 100. The default is 25.
Command Default
The default is 25 percent.
Command Modes
Router configuration (config-router)
Command History
Usage Guidelines
Note
This command is supported by OSPFv2 and OSPFv3.
Use the process-min-time percent command to configure the minimum percentage of the process maximum time. Lowering the minimum percentage of CPU usage that a process can utilize is useful in some circumstances to ensure equitable division of CPU resources among different tasks. Once the percentage has been exceeded, CPU control may be given to a higher priority process.
The process maximum time is set using the process-max-time command. Use the process-min-time percent command in conjunction with the process-max-time command.
Examples
The following example shows how to set the percentage of CPU process time to be used before releasing the CPU:
Router# configure terminalRouter(config)# router ospfRouter(config-router)# process-min-time percent 35The following example shows how to return to the default setting in IPv4:
Router# configure terminalRouter(config)# router ospfRouter(config-router)# no process-min-time percentRelated Commands
process-max-time
Configures the amount of time after which a process should voluntarily yield to another process.
redistribute maximum-prefix
To limit the number of prefixes redistributed into Open Shortest Path First (OSPF) or to generate a warning when the number of prefixes redistributed into OSPF reaches a maximum, use the redistribute maximum-prefix command in router configuration mode. To remove the values, use the no form of this command.
redistribute maximum-prefix maximum [percentage] [warning-only | withdraw]
no redistribute maximum-prefix
Syntax Description
Command Default
The percentage default is 75.
Command Modes
Router configuration (config-router)
Command History
Usage Guidelines
If someone mistakenly injects a large number of IP prefixes into IS-IS, perhaps by redistributing Border Gateway Protocol (BGP) into IS-IS, the network can be severely flooded. Limiting the number of redistributed prefixes prevents this potential problem.
When the redistribute maximum-prefix command is configured and the number of redistributed prefixes reaches the maximum value configured, no more prefixes will be redistributed (unless the warning-only keyword was configured).
The redistribution limit applies only to external IP prefixes. Default prefixes and summarized prefixes are not limited.
The limit is tracked separately for each not-so-stubby-area (NSSA) because redistribution to NSSAs is done independently for each NSSA and independently of all other regular areas.
Select a maximum value based on your knowledge of how many prefixes are redistributed on the router to the OSPF process.
Examples
Examples for IS-IS Protocol
The following example shows how to set a maximum of 600 prefixes that can be redistributed into IS-IS. If the number of prefixes redistributed reaches 75 percent of 600 (450 prefixes), a warning message is logged.
router isisredistribute maximum-prefix 600The following example shows how to set a maximum of 1200 prefixes that can be redistributed into IS-IS. If the number of prefixes redistributed reaches 80 percent of 1200 (960 prefixes), a warning message is logged.
router isisredistribute maximum-prefix 1200 80The following example shows how to allow two warning messages to be logged. The first message is logged when the number of prefixes redistributed reaches 85 percent of 600 (510 prefixes), and the second message is logged when the number of redistributed prefixes reaches 600. However, the number of redistributed prefixes is not limited.
router isisredistribute maximum-prefix 600 85 warning-onlyExamples for OSPF Routing Protocol
The following example shows how to set a maximum of 2000 prefixes that can be redistributed into OSPF process when the number of prefixes redistributed reaches 75 percent of 2000 (1500 prefixes), a warning message is logged. Another warning is logged when the limit is reached, and no more prefixes are redistributed.
router ospf 1network 10.0.0.0 0.0.0.255 area 0redistribute eigrp 10 subnetsredistribute maximum-prefix 2000The following example shows how to set a maximum of 1200 prefixes that can be redistributed into OSPF process when the number of prefixes redistributed reaches 80 percent of 1200 (960 prefixes), a warning message is logged. Another warning is logged when the limit is reached, and no more prefixes are redistributed.
router ospf 1network 10.0.0.0 0.0.0.255 area 0redistribute eigrp 10 subnetsredistribute maximum-prefix 1200 80The following example shows how to allow two warning messages to be logged. The first message is logged when the number of prefixes redistributed reaches 85 percent of 600 (510 prefixes), and the second message is logged when the number of redistributed prefixes reaches 600. However, the number of redistributed prefixes is not limited.
router ospf 1network 10.0.0.0 0.0.0.255 area 0redistribute eigrp 10 subnetsredistribute maximum-prefix 600 85 warning-onlyrouter 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
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(config)# router ospf 109This example shows a basic OSPF configuration using the router ospf command to configure OSPF 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-router)# 20Router(config-router)# exitRelated Commands
network area
Defines the interfaces on which OSPF runs and defines the area ID for those interfaces.
router-id
To use a fixed router ID, use the router-id command in router configuration mode. To force Open Shortest Path First (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
clear ip ospf
Clears redistribution based on the OSPF routing process ID.
router ospf
Configures the OSPF routing process.
