Routing Command Reference for Cisco NCS 6000 Series Routers

address-family (OSPF)

To enter address family configuration mode for Open Shortest Path First (OSPF), use the address-family command in the appropriate mode. To disable address family configuration mode, use the no form of this command.

address-family ipv4 [unicast]

no address-family ipv4 [unicast]

Syntax Description


ipv4	Specifies IP Version 4 (IPv4) address prefixes.
unicast	(Optional) Specifies unicast address prefixes.

Command Default

An address family is not specified.

Command Modes

Router configuration

Command History


Release	Modification
Release 5.0.0	This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

OSPF version 2 automatically provides routing services for IPv4 unicast topologies, so this command is redundant.

Task ID


Task ID	Operations
ospf	read, write

Examples

The following example shows how to configure the OSPF router process with IPv4 unicast address prefixes:


RP/0/RP0/CPU0:router(config)# router ospf 1
RP/0/RP0/CPU0:router(config-ospf)# address-family ipv4 unicast

adjacency stagger

To configure staggering of OSPF adjacency during reload, process restart, and process clear, use the adjacency stagger command in router configuration mode. To turn off adjacency staggering, either use the disable keyword or use the no form of this command.

adjacency stagger {disable | initial-num-nbr max-num-nbr}

no adjacency stagger

Syntax Description


disable	Disables adjacency staggering.
`initial-num-nbr`	The initial number of simultaneous neighbors allowed to form adjacency to FULL in any area to bring up to FULL after a router reload, OSPF process restart, or OSPF process clear. Range is 1-65535. Default is 2.
`max-num-nbr`	The subsequent number of simultaneous neighbors allowed to form adjacency, per OSPF instance, after the initial set of OSPF neighbors have become FULL. Range is 1-65535. Default is 64.

Command Default

OSPF adjacency staggering is enabled.

Command Modes

Router configuration

Command History


Release	Modification
Release 5.0.0	This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

Staggering of the OSPF adjacency during reload, process restart (without NSR or graceful-restart), and process clear reduces the overall adjacency convergence time.

Initially, allow 2 (configurable) neighbors to form adjacency to FULL per area. After the first adjacency reaches FULL, up to 64 (configurable) neighbors can form adjacency simultaneously for the OSPF instance (all areas). However, areas without any FULL adjacency is restricted by the initial area limit.

Note

Adjacency stagger and OSPF nonstop forwarding (NSF) are mutually exclusive. Adjacency stagger will not be activated if nsf is configured under router ospf configuration.

Task ID


Task ID	Operations
ospf	read, write

Examples

The following example shows how to configure adjacency stagger for a 2 neighbors initially and for a maximum of 3 neighbors:


  RP/0/RP0/CPU0:router# configure
  RP/0/RP0/CPU0:router(config)# router ospf 1
  RP/0/RP0/CPU0:router(config-ospf)# adjacency stagger 2 3

area (OSPF)

To configure an Open Shortest Path First (OSPF) area, use the area command in the appropriate mode. To terminate an OSPF area, use the no form of this command.

area area-id

no area area-id

Syntax Description


`area-id`	Identifier of an OSPF area. The area-id argument can be specified as either a decimal value or an IP address (dotted decimal) format. Range is 0 to 4294967295.

Command Default

No OSPF area is defined.

Command Modes

Router configuration

Command History


Release	Modification
Release 5.0.0	This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

Use the area command to explicitly configure an area. Commands configured under the area configuration mode (such as the interface [OSPF] and authentication commands), are automatically bound to that area.

To modify or remove the area, the area-id argument format must be the same as the format used when creating the area. Otherwise, even if the actual 32-bit value matches, the area is not matched. For example, if you create an area with an area-id of 10 it would not match an area-id of 0.0.0.10.

Note

To remove the specified area from the router configuration, use the no area area-id command. The no area area-id command removes the area and all area options, such as authentication , default-cost , nssa , range , stub , virtual-link , and interface.

Task ID


Task ID	Operations
ospf	read, write

Examples

The following example shows how to configure area 0 and GigabitEthernet interface 0/2/0/0. GigabitEthernet interface 0/2/0/0 is bound to area 0 automatically.


  RP/0/RP0/CPU0:router# configure
  RP/0/RP0/CPU0:router(config)# router ospf 1
  RP/0/RP0/CPU0:router(config-ospf)# area 0
  RP/0/RP0/CPU0:router(config-ospf-ar)# interface GigabitEthernet 0/2/0/0

authentication (OSPF)

To enable plain-text authentication, Message Digest 5 (MD5) authentication, Keychain-based authentication or null authentication for an Open Shortest Path First (OSPF) interface, use the authentication command in the appropriate mode. To remove such authentication, use the no form of this command.

authentication [message-digest [keychain keychain ] | [keychain keychain ] | | null]

no authentication

Syntax Description


message-digest	(Optional) Specifies that MD5 is used.
keychain `keychain`	(Optional) Specifies a keychain name.
keychain `keychain`	(Optional) Enables Keychain-based authentication.
null	(Optional) Specifies that no authentication is used. Useful for overriding password or MD5 authentication if configured for an area.

Command Default

If this command is not specified in interface configuration mode, then the interface adopts the authentication parameter specified by the area.

If this command is not specified in area configuration mode, then the interface adopts the authentication parameter specified for the process.

If this command is not specified at any level, then the interface does not use authentication.

If no keyword is specified, plain text authentication is used.

Command Modes

Interface configuration

Area configuration

Router configuration

Virtual-link configuration

Multi-area interface configuration

Sham-link configuration

Command History


Release	Modification
Release 5.0.0	This command was introduced.
Release 6.5.1	The Keychain keyword was introduced to enable Keychain-based authentication.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

Use the authentication command to specify an authentication type for the interface, which overrides the authentication specified for the area to which this interface belongs. If this command is not included in the configuration file, the authentication configured in the area to which the interface belongs is assumed (as specified by the area authentication command).

The authentication type and password must be the same for all OSPF interfaces that are to communicate with each other through OSPF. If you specified plain text authentication, use the authentication-key command to specify the plain text password.

If you enable MD5 authentication with the message-digest keyword, you must configure a key with the message-digest-key interface command.

To manage the rollover of keys and enhance MD5 authentication for OSPF, you can configure a container of keys called a keychain with each key comprising the following attributes: generate/accept time, key identification, and authentication algorithm. The keychain management feature is always enabled.

Note

Changes to the system clock will impact the validity of the keys in the existing configuration.

Task ID


Task ID	Operations
ospf	read, write

Examples

The following example shows how to set authentication for areas 0 and 1 of OSPF routing process 201. Authentication keys are also provided.


  RP/0/RP0/CPU0:router# configure
  RP/0/RP0/CPU0:router(config)# router ospf 201
  RP/0/RP0/CPU0:router(config-ospf)# router-id 10.1.1.1
  RP/0/RP0/CPU0:router(config-ospf)# area 0
  RP/0/RP0/CPU0:router(config-ospf-ar)# authentication
  RP/0/RP0/CPU0:router(config-ospf-ar)# interface GigabitEthernet 0/1/0/1
  RP/0/RP0/CPU0:router(config-ospf-ar-if)# authentication-key mykey
  RP/0/RP0/CPU0:router(config-ospf-ar-if)# exit
  RP/0/RP0/CPU0:router(config-ospf)# area 1 
  RP/0/RP0/CPU0:router(config-ospf-ar)# authentication
  RP/0/RP0/CPU0:router(config-ospf-ar)# interface GigabitEthernet 0/1/0/0
  RP/0/RP0/CPU0:router(config-ospf-ar-if)# authentication-key mykey1

The following example shows how to configure use of an authentication keychain:


  RP/0/RP0/CPU0:router# configure
  RP/0/RP0/CPU0:router(config)# router ospf 201
  RP/0/RP0/CPU0:router(config-ospf)# router-id 10.1.1.1
  RP/0/RP0/CPU0:router(config-ospf)# authentication message-digest keychain mykeychain

The following example shows how to configure keychain-based authentication:

RP/0/RP0/CPU0:router(config-ospf)#authentication keychain ?
  WORD  The keychain name
RP/0/RP0/CPU0:router(config-ospf)#authentication keychain test_chain ----- Router level authentication
RP/0/RP0/CPU0:router(config-ospf)#router-id 1.1.1.1
RP/0/RP0/CPU0:router(config-ospf)#address-family ipv4 unicast
RP/0/RP0/CPU0:router(config-ospf)#area 1 
RP/0/RP0/CPU0:router(config-ospf-ar)#authentication keychain test_chain ----- Area level authentication
RP/0/RP0/CPU0:router(config-ospf-ar)#interface TenGigE 0/0/0/1
RP/0/RP0/CPU0:router(config-ospf-ar-if)#authentication keychain test_chain ----- Interface level authentication
RP/0/RP0/CPU0:router(config-ospf-ar-if)#commit

Related Commands


Command	Description
authentication-key (OSPF)	Assigns a password to be used by neighboring routers that are using the simple password authentication of OSPF.
message-digest-key	Specifies a key used with OSPF MD5 authentication.

authentication-key (OSPF)

To assign a password to be used by neighboring routers that are using the Open Shortest Path First (OSPF) simple password authentication, use the authentication-key command in the appropriate mode. To remove a previously assigned OSPF password, use the no form of this command.

authentication-key [clear | encrypted] password

no authentication-key

Syntax Description


clear	(Optional) Specifies that the key be clear text.
encrypted	(Optional) Specifies that the key be encrypted using a two-way algorithm.
`password`	Any contiguous string up to 8 characters in length that can be entered from the keyboard. For example, mypswd2.

Command Default

If this command is not specified in interface configuration mode, then the interface adopts the OSPF password parameter specified by the area.

If this command is not specified in area configuration mode, then the interface adopts the OSPF password parameter specified for the process.

If this command is not specified at any level, then no password is specified.

Clear is the default if the clear or encrypted keyword is not specified.

Command Modes

Interface configuration

Area configuration

Router configuration

Virtual-link configuration

Multi-area configuration

Sham-link configuration

Command History


Release	Modification
Release 5.0.0	This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

The password created by this command is inserted directly into the OSPF header when the Cisco IOS XR software originates routing protocol packets. A separate password can be assigned to each network on an individual interface basis. All neighboring routers on the same network must have the same password to be able to exchange OSPF information.

The authentication-key command must be used with the authentication command. If the authentication command is not configured, the password provided by the authentication-key command is ignored and no authentication is adopted by the OSPF interface.

Note

The authentication-key command cannot be used with the authentication command when the message-digest or null keyword is configured.

Task ID


Task ID	Operations
ospf	read, write

Examples

The following example shows how to configure an authentication password as the string yourpass:


  RP/0/RP0/CPU0:router# configure
  RP/0/RP0/CPU0:router(config)# router ospf 201
  RP/0/RP0/CPU0:router(config-ospf)# authentication-key yourpass

Related Commands


Command	Description
authentication (OSPF)	Specifies authentication type.

auto-cost (OSPF)

To control how the Open Shortest Path First (OSPF) protocol calculates default metrics for the interface, use the auto-cost command in the appropriate mode. To revert to the default reference bandwidth, use the no form of this command.

auto-cost {reference-bandwidth mbps | disable}

no auto-cost {reference-bandwidth | disable}

Syntax Description


reference-bandwidth `mbps`	Specifies a rate in Mbps (bandwidth). Range is 1 to 4294967.
disable	Assigns a cost based on interface type.

Command Default

mbps : 100 Mbps

Command Modes

Router configuration

Command History


Release	Modification
Release 5.0.0	This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

By default OSPF calculates the OSPF metric for an interface according to the bandwidth of the interface.

The OSPF metric is calculated as the mbps value divided by bandwidth, with mbps equal to 108 by default.

If you have multiple links with high bandwidth (such as OC-192), you might want to use a larger number to differentiate the cost on those links. That is, the metric calculated using the default mbps value is the same for all high-bandwidth links.

Recommended usage of cost configuration for OSPF interfaces with high bandwidth is to be consistent: Either explicitly configure (by using the cost command) or choose the default (by using the auto-cost command).

The value set by the cost command overrides the cost resulting from the auto-cost command.

Task ID


Task ID	Operations
ospf	read, write

Examples

The following example shows how to set the reference value for the auto cost calculation to 1000 Mbps:


  RP/0/RP0/CPU0:router# configure
  RP/0/RP0/CPU0:router(config)# router ospf 1
  RP/0/RP0/CPU0:router(config-ospf)# auto-cost reference-bandwidth 1000

Related Commands


Command	Description
cost (OSPF)	Explicitly specifies the cost of the interface (network) for OSPF path calculation.

capability opaque disable

To prevent Multiprotocol Label Switching traffic engineering (MPLS TE) topology information flooded to the network through opaque LSAs, use the capability opaque disable command in the appropriate mode. To restore MPLS TE topology information flooded through opaque LSAs to the network, use the no form of the command.

capability opaque disable

no capability opaque disable

Command Default

Opaque LSAs are allowed.

Command Modes

Router configuration

Command History


Release	Modification
Release 5.0.0	This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

The capability opaque disable command prevents flooded MPLS TE information (Types 1 and 4) through opaque LSAs of all scope (Types 9, 10, and 11).

Control opaque LSA support capability must be enabled for OSPF to support MPLS TE.

The MPLS TE topology information is flooded to the area through opaque LSAs by default.

Task ID


Task ID	Operations
ospf	read, write

Examples

The following example shows how to prevent OSPF from supporting opaque services:


  RP/0/RP0/CPU0:router# configure
  RP/0/RP0/CPU0:router(config)# router ospf 1
  RP/0/RP0/CPU0:router(config-ospf)# capability opaque disable

clear ospf process

To reset an Open Shortest Path First (OSPF) router process without stopping and restarting it, use the clear ospf process command in XR EXEC mode.

clear ospf process

Syntax Description


`process-name`	(Optional) Name that uniquely identifies an OSPF routing process. The process name is defined by the router ospf command. If this argument is included, only the specified routing process is affected. Otherwise, all OSPF processes are reset.

Command Default

No default behavior or value

Command Modes

XR EXEC

Command History


Release	Modification
Release 5.0.0	This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

When the OSPF router process is reset, OSPF releases all resources allocated, cleans up the internal database, and shuts down and restarts all interfaces that belong to the process.

Note

The clear ospf process command may change the router ID unless the OSPF router ID is explicitly configured through the router-id (OSPF) command.

Task ID


Task ID	Operations
ospf	read, write

Examples

The following example shows how to reset all OSPF processes:


  RP/0/RP0/CPU0:router# clear ospf process

The following example shows how to reset the OSPF 1 process:


RP/0/RP0/CPU0:router# clear ospf 1 process

Related Commands


Command	Description
router ospf	Configures an OSPF routing process.
router-id (OSPF)	Configures a router ID for the OSPF process.

clear ospf redistribution

To clear all routes redistributed from other protocols out of the Open Shortest Path First (OSPF) routing table, use the clear ospf redistribution command in XR EXEC mode.

clear ospf redistribution

Syntax Description


`process-name`	(Optional) Name that uniquely identifies an OSPF routing process. The process name is defined by the router ospf command. If this argument is included, only the specified routing process is affected. Otherwise, all OSPF routes are cleared.

Command Default

No default behavior or value

Command Modes

XR EXEC

Command History


Release	Modification
Release 5.0.0	This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

Use the clear ospf redistribution command to cause the routing table to be read again. OSPF regenerates and sends Type 5 and Type 7 link-state advertisements (LSAs) to its neighbors. If an unexpected route has appeared in the OSPF redistribution, using this command corrects the issue.

Note

Use of this command can cause a significant number of LSAs to flood the network. We recommend that you use this command with caution.

Task ID


Task ID	Operations
ospf	read, write

Examples

The following example shows how to clear all redistributed routes across all processes from other protocols:


RP/0/RP0/CPU0:router# clear ospf redistribution

clear ospf routes

To clear all Open Shortest Path First (OSPF) routes from the OSPF routing table, use the clear ospf routes command in XR EXEC mode.

clear ospf routes

Syntax Description


`process-name`	(Optional) Name that uniquely identifies an OSPF routing process. The process name is defined by the router ospf command. If this argument is included, only the specified routing process is affected. Otherwise, all OSPF routes are cleared.

Command Default

No default behavior or value

Command Modes

XR EXEC

Command History


Release	Modification
Release 5.0.0	This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

Task ID


Task ID	Operations
ospf	read, write

Examples

The following example shows how to clear all OSPF routes from the OSPF routing table and recompute valid routes. When the OSPF routing table is cleared, OSPF routes in the global routing table are also recalculated.


RP/0/RP0/CPU0:router# clear ospf routes

Related Commands


Command	Description
router ospf	Configures an OSPF routing process.

clear ospf statistics

To clear the Open Shortest Path First (OSPF) statistics of neighbor state transitions, use the clear ospf statistics command in XR EXEC mode.

clear ospf statistics [neighbor [type interface-path-id] [ip-address] ]

Syntax Description


`process-name`	(Optional) Name that uniquely identifies an OSPF routing process. The process name is defined by the router ospf command. If this argument is included, only the specified routing process is affected. Otherwise, all OSPF statistics of neighbor state transitions are cleared.
neighbor	(Optional) Clears the state transition counters of the specified neighbor only.
`type`	(Optional) Interface type. For more information, use the question mark (?) online help function.
`interface-path-id`	(Optional) Physical interface or virtual interface. Use the show interfaces command to see a list of all interfaces currently configured on the router. For more information about the syntax for the router, use the question mark (?) online help function.
`ip-address`	(Optional) IP address of a specified neighbor for whom you want to clear the state transition counter.

Command Default

No default behavior or value

Command Modes

XR EXEC

Command History


Release	Modification
Release 5.0.0	This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

Use the clear ospf statistics command to reset OSPF counters. Reset is useful to detect changes in counter values.

Task ID


Task ID	Operations
ospf	read, write

Examples

The following example shows how to reset the OSPF transition state counters for all neighbors on Packet-over-SONET/SDH (POS) interface 0/2/0/0:

RP/0/RP0/CPU0:router# clear ospf statistics neighbor POS 0/2/0/0

Related Commands


Command	Description
router ospf	Configures an OSPF routing process.

clear ospf statistics interface

To clear the Open Shortest Path First (OSPF) statistics per interface, use the clear ospf statistics interface command in XR EXEC mode.

clear ospf statistics interface type interface-path-id

Syntax Description

type

Interface type. For more information, use the question mark (?) online help function.

interface-path-id

Physical interface or virtual interface.

Note

Use the show interfaces command to see a list of all interfaces currently configured on the router.

For more information about the syntax for the router, use the question mark (?) online help function.

Command Default

No default behavior or value.

Command Modes

XR EXEC

Command History


Release	Modification
Release 5.0.0	This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

Use the clear ospf statistics interface command to reset OSPF counters. Reset is useful to detect changes in counter values.

Task ID


Task ID	Operations
ospf	read, write

Examples

The following example shows how to reset OSPF statistics for interface POS 0/21/0/0:

RP/0/RP0/CPU0:router# clear ospf statistics interface POS 0/21/0/0

Related Commands


Command	Description
clear ospf statistics	Clears the Open Shortest Path First (OSPF) statistics of neighbor state transitions.

cost (OSPF)

To explicitly specify the interface (network) for Open Shortest Path First (OSPF) path calculation, use the cost command in the appropriate mode. To remove the cost, use the no form of this command.

cost cost

no cost

Syntax Description


`cost`	Unsigned integer value expressed as the link-state metric. Range is 1 to 65535.

Command Default

If this command is not specified in interface configuration mode, then the interface adopts the cost parameter specified by the area.

If this command is not specified in area configuration mode, then the interface adopts the cost parameter specified for the process.

If this command is not specified at any level, then the cost is calculated by the auto-cost command.

Command Modes

Interface configuration

Area configuration

Router configuration

Multi-area configuration

Sham-link configuration

Command History


Release	Modification
Release 5.0.0	This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

The link-state metric is advertised as the link cost in the router link advertisement. Cisco IOS XR software does not support type of service (ToS), so you can assign only one cost for each interface.

In general, the path cost is calculated using the following formula:

108 / bandwidth (the default auto cost is set to 100 Mbps)

This calculation is the default reference bandwidth used by the auto-costing calculation which establishes the interface auto-cost The auto-cost command can set this reference bandwidth to some other value. The cost command is used to override the auto-costing calculated default value for interfaces.

Using this formula, the default path cost is 1 for any interface that has a link bandwidth of 100 Mbps or higher. If this value does not suit the network, configure the reference bandwidth for auto calculating costs based on the link bandwidth.

The value set by the cost command overrides the cost resulting from the auto-cost (OSPF) command.

Task ID


Task ID	Operations
ospf	read, write

Examples

The following example shows how to set the cost value to 65 for GigabitEthernet interface 0/1/0/1:


  RP/0/RP0/CPU0:router# configure
  RP/0/RP0/CPU0:router(config)# router ospf 1
  RP/0/RP0/CPU0:router(config-ospf)# area 0
  RP/0/RP0/CPU0:router(config-ospf-ar)# interface GigabitEthernet 0/1/0/1
  RP/0/RP0/CPU0:router(config-ospf-ar-if)# cost 65

Related Commands


Command	Description
auto-cost (OSPF)	Controls how the OSPF protocol calculates default metrics for the interface.

cost-fallback (OSPF)

To apply higher cost than the normal interface cost when the cumulative bandwidth of a bundle interface goes below the threshold specified and to revert to the original cost if the cumulative bandwidth goes above the configured threshold, use the cost-fallback command. To remove the cost-fallback, use the no form of this command.

cost-fallback cost threshold bandwidth

no cost-fallback

Syntax Description


`cost` threshold	Unsigned integer value expressed as the link-state metric. Range is 1 to 65535, but typically, cost-fallback value is supposed to be set to a value higher than the normal cost.
`bandwidth`	Unsigned integer value expressed in Mbits per second. Range is 1 to 4294967.

Command Default

If this command is not specified in interface configuration mode, the currently effective interface cost takes effect even when the cumulative bandwidth goes down below the maximum bandwidth. Unlike the interface cost command, this cost-fallback command is available only under interface configuration mode; it is not available in area or process level. Unlike other interface specific parameters, no inheritance will take place from area or process level if this command is not specified at interface level.

Command Modes

Interface configuration

Command History


Release	Modification
Release 5.0.0	This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

The fallback cost must be set to a higher value than the normal interface cost. The motivation of setting the fallback cost is to cost out an interface or disfavor an interface without shutting it down when its cumulative bandwidth goes below the user specified threshold, so that the traffic can take an alternative path. The normal interface cost will take over when the cumulative bandwidth reaches or exceeds user-specified threshold.

Task ID


Task ID	Operations
ospf	read, write

Examples

The following example shows how to set the cost-fallback value for Packet-over-SONET/SDH (POS):


  RP/0/RP0/CPU0:router# configure
  RP/0/RP0/CPU0:router(config)#router ospf 100
  RP/0/RP0/CPU0:router(config-ospf)#router-id 2.2.2.2
  RP/0/RP0/CPU0:router(config-ospf)#area 0
  RP/0/RP0/CPU0:router(config-ospf-ar)#interface bundle-
  RP/0/RP0/CPU0:router(config-ospf-ar-if)#cost-fallback 1000 threshold 300

Related Commands


Command	Description
auto-cost (OSPF)	Controls how the OSPF protocol calculates default metrics for the interface.
cost (OSPF)	Specifies the cost of the interface (network) for OSPF path calculation.

database-filter all out (OSPF)

To filter outgoing link-state advertisements (LSAs) to an Open Shortest Path First (OSPF) interface, use the database-filter all out command in the appropriate mode. To restore the forwarding of LSAs to the interface, use the disable form of the command.

database-filter all out [disable | enable]

Syntax Description


disable	(Optional) Disables filtering.
enable	(Optional) Enables filtering.

Command Default

The database filter is disabled.

Command Modes

Interface configuration

Area configuration

Router configuration

VRF configuration

Multi-area configuration

Command History


Release	Modification
Release 6.0	This command was introduced.

Usage Guidelines

No specific guidelines impact the use of this command.

Use the database-file all out command to perform the same function that the neighbor database-filter all out command performs on a neighbor basis.

Task ID


Task ID	Operations
ospf	read, write

Examples

The following example shows how to prevent flooding of OSPF LSAs to broadcast, nonbroadcast, and point-to-point networks reachable through GigabitEthernet interface 0/1/0/1:


  RP/0/RP0/CPU0:router# configure
  RP/0/RP0/CPU0:router(config)# router ospf 1
  RP/0/RP0/CPU0:router(config-ospf)# area 0
  RP/0/RP0/CPU0:router(config-ospf-ar)# interface GigabitEthernet 0/1/0/1
  RP/0/RP0/CPU0:router(config-ospf-ar-if)# database-filter all out

dead-interval (OSPF)

To set the interval after which a neighbor is declared dead when no hello packets are observed, use the dead-interval command in the appropriate mode. To return to the default time, use the no form of this command.

dead-interval seconds

no dead-interval

Syntax Description


`seconds`	Integer that specifies the interval (in seconds). Range is 1 to 65535. The value must be the same for all nodes on the network.

Command Default

If this command is not specified in interface configuration mode, then the interface adopts the dead interval parameter specified by the area.

If this command is not specified in area configuration mode, then the interface adopts the dead interval parameter specified for the process.

If this command is not specified at any level, then the dead interval is four times the interval set by the hello-interval (OSPF) command.

Command Modes

Interface configuration

Area configuration

Router configuration

Virtual-link configuration

Multi-area configuration

Sham-link configuration

Command History


Release	Modification
Release 5.0.0	This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

The dead interval value must be the same for all routers and access servers on a specific network.

If the hello interval is configured, the dead interval value must be larger than the hello interval value. The dead interval value is usually configured four times larger than the hello interval value.

Task ID


Task ID	Operations
ospf	read, write

Examples

The following example shows how to set the OSPF dead interval to 40 seconds:


  RP/0/RP0/CPU0:router# configure
  RP/0/RP0/CPU0:router(config)# router ospf 1
  RP/0/RP0/CPU0:router(config-ospf)# area 0
  RP/0/RP0/CPU0:router(config-ospf-ar)# interface GigabitEthernet 0/1/0/1
  RP/0/RP0/CPU0:router(config-ospf-ar-if)# dead-interval 40

Related Commands


Command	Description
hello-interval (OSPF)	Specifies the interval between hello packets that the Cisco IOS XR software sends on the interface.

default-cost (OSPF)

To specify a cost for the default summary route sent into a stub area or not-so-stubby area (NSSA), use the default-cost command in area configuration mode. To remove the assigned default route cost, use the no form of this command.

default-cost cost

no default-cost cost

Syntax Description


`cost`	Cost for the default summary route used for a stub or NSSA area. The acceptable value is a 24-bit number.

Command Default

cost : 1

Command Modes

Area configuration

Command History


Release	Modification
Release 5.0.0	This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

Use the default-cost command only on an Area Border Router (ABR) attached to a stub or an NSSA area.

In all routers and access servers attached to the stub area, the area should be configured as a stub area using the stub command in the area submode. Use the default-cost command only on an ABR attached to the stub area. The default-cost command provides the metric for the summary default route generated by the ABR into the stub area.

Task ID


Task ID	Operations
ospf	read, write

Examples

The following example shows how to assign a default cost of 20 to a stub area. The GigabitEthernet interface 0/4/0/3 is also configured in the stub area:


  RP/0/RP0/CPU0:router# configure
  RP/0/RP0/CPU0:router(config)# router ospf 201
  RP/0/RP0/CPU0:router(config-ospf)# area 10.15.0.0
  RP/0/RP0/CPU0:router(config-ospf-ar)# stub
  RP/0/RP0/CPU0:router(config-ospf-ar)# default-cost 20
  RP/0/RP0/CPU0:router(config-ospf-ar)# interface GigabitEthernet 0/4/0/3

Related Commands


Command	Description
stub (OSPF)	Defines an area as a stub area.

default-information originate (OSPF)

To generate a default external route into an Open Shortest Path First (OSPF) routing domain, use the default-information originate command in the appropriate mode. To disable this feature, use the no form of this command.

default-information originate [always] [metric metric-value] [metric-type type-value] [route-policy policy-name] [tag tag-value]

no default-information originate

Syntax Description


always	(Optional) Always advertises the default route regardless of whether the routing table has a default route.
metric `metric-value`	(Optional) Specifies the metric used for generating the default route. The default metric value is 1. Range is 1 to 16777214.
metric-type `type-value`	(Optional) Specifies the 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
tag `tag-value`	(Optional) 32-bit dotted-decimal value attached to each external route. This is not used by the OSPF protocol itself. It may be used to communicate information between autonomous system boundary routers (ASBRs). If a tag is not specified, then the configured OSPF process number is used.
route-policy `policy-name`	(Optional) Specifies that a routing policy be used and the routing policy name.

Command Default

When you do not use this command in router configuration mode, no default external route is generated into an OSPF routing domain.

metric-value : 1

type-value : 2

tag-value : configured OSPF process number

Command Modes

Router configuration

Command History


Release	Modification
Release 5.0.0	This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

Whenever you use the redistribute or default-information originate command to redistribute routes into an OSPF routing domain, the 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.

The default-information originate route-policy attach point conditionally injects the default route 0.0.0.0/0 into the OSPF link-state database, and is done by evaluating the attached policy. If any routes specified in the policy exist in the global RIB, then the default route is inserted into the link-state database. If there is no match condition specified in the policy, the policy passes and the default route is generated into the link-state database.

For information about the default-information originate attach point, see the OSPF Policy Attach Points section in the Implementing Routing Policy chapter in Routing Configuration Guide for Cisco NCS 6000 Series Routers.

For information about routing policies, see the Routing Policy Commands chapter in the Routing Command Reference for Cisco NCS 6000 Series Routers.

Task ID


Task ID	Operations
ospf	read, write

Examples

The following example shows how to specify a metric of 100 for the default route redistributed into the OSPF routing domain and an external metric type of Type 1:


RP/0/RP0/CPU0:router#configure
RP/0/RP0/CPU0:router(config)#router ospf 109
RP/0/RP0/CPU0:router(config-ospf)#redistribute igrp 108 metric 100
RP/0/RP0/CPU0:router(config-ospf)#default-information originate metric 100 metric-type 1

Related Commands


Command	Description
redistribute (OSPF)	Redistributes routes from one routing domain into a specified OSPF process.

default-metric (OSPF)

To set default metric values for routes redistributed from another protocol into the Open Shortest Path First (OSPF) protocol, use the default-metric command in the appropriate mode. To return to the default state, use the no form of this command.

default-metric value

no default-metric value

Syntax Description


`value`	Default metric value appropriate for the specified routing protocol. Range is 1 to 16777214.

Command Default

Built-in, automatic metric translations, as appropriate for each routing protocol.

Command Modes

Router configuration

Command History


Release	Modification
Release 5.0.0	This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

Use the default-metric command with the redistribute 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, use a default metric to provide a reasonable substitute and enable the redistribution to proceed.

The default-metric value configured in OSPF configuration does not apply to connected routes that are redistributed to OSPF using the redistribute connected command. To set a non-default metric for connected routes, configure OSPF with the redistribute connected metric metric-value command.

Task ID


Task ID	Operations
ospf	read, write

Examples

The following example shows how to advertise Intermediate System-to-Intermediate System (IS-IS) protocol-derived routes into OSPF and assign a metric of 10:


  RP/0/RP0/CPU0:router# configure
  RP/0/RP0/CPU0:router(config)# router ospf 1
  RP/0/RP0/CPU0:router(config-ospf)# default-metric 10
  RP/0/RP0/CPU0:router(config-ospf)# redistribute isis IS-IS_isp

Related Commands


Command	Description
redistribute (OSPF)	Redistributes routes from one routing domain into a specified OSPF process.

demand-circuit (OSPF)

To configure the Open Shortest Path First (OSPF) protocol to treat the interface as an OSPF demand circuit, use the demand-circuit command in the appropriate mode. To remove the demand circuit designation from the interface, use the no form of this command.

demand-circuit [disable | enable]

no demand-circuit

Syntax Description


disable	(Optional) Disables the interface as an OSPF demand circuit.
enable	(Optional) Enables the interface as an OSPF demand circuit.

Command Default

If this command is not specified in interface configuration mode, then the interface adopts the demand circuit parameter specified by the area.

If this command is not specified in area configuration mode, then the interface adopts the demand circuit parameter specified for the process.

If this command is not specified at any level, then the circuit is not a demand circuit.

Command Modes

Interface configuration

Area configuration

Router configuration

Command History


Release	Modification
Release 5.0.0	This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

On point-to-point interfaces, only one end of the demand circuit must be configured with this command. Periodic hello messages are suppressed and periodic refreshes of link-state advertisements (LSAs) do not flood the demand circuit. Use the demand-circuit command to allow the underlying data link layer to be closed when the topology is stable. In point-to-multipoint topology, only the multipoint end must be configured with this command.

Task ID


Task ID	Operations
ospf	read, write

Examples

The following example shows how to set the configuration for an OSPF demand circuit:


  RP/0//CPU0:router# configure
  RP/0//CPU0:router(config)# router ospf 1
  RP/0//CPU0:router(config-ospf)# demand-circuit

distance (OSPF)

To define an administrative distance, use the distance command in an appropriate configuration mode. To remove the distance command from the configuration file and restore the system to its default condition in which the software removes a distance definition, use the no form of this command.

distance weight [ip-address wildcard-mask [access-list-name] ]

no distance weight ip-address wildcard-mask [access-list-name]

Syntax Description


`weight`	Administrative distance. Range is 10 to 255. Used alone, the weight argument specifies a default administrative distance that the software uses when no other specification exists for a routing information source. Routes with a distance of 255 are not installed in the routing table. lists the default administrative distances. Table 1
`ip-address`	(Optional) IP address in four-part, dotted-decimal notation.
`wildcard-mask`	(Optional) Wildcard mask in four-part, dotted decimal format. A bit set to 1 in the mask argument instructs the software to ignore the corresponding bit in the address value.
`access-list-name`	(Optional) Name of an IP access list to be applied to incoming routing updates.

Command Default

If this command is not specified, then the administrative distance is the default, as specified in Table 1.

Command Modes

Router configuration

Command History


Release	Modification
Release 5.0.0	This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

An administrative distance is an integer from 10 to 255. In general, the higher the value, the lower the trust rating. An administrative distance of 255 means that the routing information source cannot be trusted at all and should be ignored. Weight values are subjective; no quantitative method exists for choosing weight values.

If an access list is used with this command, it is applied when a network is being inserted into the routing table. This behavior allows you to filter networks based on the IP prefix supplying the routing information. For example, you could filter possibly incorrect routing information from networking devices not under your administrative control.

The order in which you enter distance commands can affect the assigned administrative distances in unexpected ways (see the “Examples” section for further clarification).

This table lists default administrative distances.

Table 1. Default Administrative Distances
Route Source	Default Distance
Connected interface	0
Static route out on interface	0
State route to next-hop	1
EIGRP Summary Route	5
External BGP	20
Internal EIGRP	90
OSPF	110
IS-IS	115
RIP version 1 and 2	120
External EIGRP	170
Internal BGP	200
Unknown	255

Task ID


Task ID	Operations
ospf	read, write

Examples

In the following example, the router ospf command sets up OSPF routing instance1. The first distance command sets the default administrative distance to 255, which instructs the software to ignore all routing updates from networking devices for which an explicit distance has not been set. The second distance command sets the administrative distance for all networking devices on the Class C network 192.168.40.0 0.0.0.255 to 90.


RP/0/RP0/CPU0:router# configure
RP/0/RP0/CPU0:router(config)# router ospf 1
RP/0/RP0/CPU0:router(config-ospf)# distance 255
RP/0/RP0/CPU0:router(config-ospf)# distance 90 192.168.40.0 0.0.0.255

Related Commands


Command	Description
distance bgp	Allows the use of external, internal, and local administrative distances that could be a better route to a BGP node.
distance ospf	Allows the use of external, internal, and local administrative distances that could be a better route to an OSPF node.
router ospf	Configures the OSPF routing process.

distance ospf

To define Open Shortest Path First (OSPF) route administrative distances based on route type, use the distance ospf command in router configuration mode. To restore the default value, use the no form of this command.

distance ospf {intra-area | inter-area | external} distance

no distance ospf

Syntax Description


intra-area \| inter-area \| external	Sets the type of area. It can be one of the following values: intra-area —All routes within an area. inter-area —All routes from one area to another area. external —All routes from other routing domains, learned by redistribution. Any combination of the above areas is allowed.
`distance`	Route administrative distance.

Command Default

distance : 110

Command Modes

Router configuration

Command History


Release	Modification
Release 5.0.0	This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

You must specify one of the keywords.

Use the distance ospf command to perform the same function as the distance command used with an access list. However, the distance ospf command sets a distance for an entire group of routes, rather than a specific route that passes an access list.

A common reason to use the distance ospf command is when you have multiple OSPF processes with mutual redistribution, and you want to prefer internal routes from one over external routes from the other.

Task ID


Task ID	Operations
ospf	read, write

Examples

The following example shows how to change the external distance to 200, making the route less reliable:


  RP/0/RP0/CPU0:router# configure
  RP/0/RP0/CPU0:router(config)# router ospf 1
  RP/0/RP0/CPU0:router(config-ospf)# redistribute ospf 2 
  RP/0/RP0/CPU0:router(config-ospf)# distance ospf external 200
  RP/0/RP0/CPU0:router(config-ospf)# exit
  RP/0/RP0/CPU0:router(config)# router ospf 2
  RP/0/RP0/CPU0:router(config-ospf)# redistribute ospf 1 
  RP/0/RP0/CPU0:router(config-ospf)# distance ospf external 200

distribute-list

To filter networks received or transmitted in Open Shortest Path First (OSPF) updates, use the distribute-list command in the appropriate mode. To change or cancel the filter, use the no form of this command.

distribute-list {access-list-name {in | out [bgp number | connected | ospf instance | static]}}

no distribute-list {access-list-name {in | out}}

Syntax Description


`access-list-name`	Standard IP access list name. The list defines which networks are to be received and which are to be suppressed in routing updates.
in	Applies the access list or route-policy to incoming routing updates.
out	Applies the access list to outgoing routing updates. The out keyword is available only in router configuration mode.
bgp	(Optional) Applies the access list to BGP routes.
connected	(Optional) Applies the access list to connected routes.
ospf	(Optional) Applies the access list to OSPF routes (not the current OSPF process).
static	(Optional) Applies the access list to statically configured routes.

Command Default

If this command is not specified in interface configuration mode, then the interface adopts the distribute list parameter specified by the area.

If this command is not specified in area configuration mode, then the interface adopts the distribute list parameter specified for the process.

If this command is not specified at any level, then the distribute list is disabled.

Command Modes

Interface configuration

Area configuration

Router configuration

Multi-area configuration

Command History


Release	Modification
Release 5.0.0	This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

Use the distribute-list command to limit which OSPF routes are installed on this router. The distribute-list command does not affect the OSPF protocol itself.

The distribute-list in is configurable at instance (process), area, and interface levels. Regular OSPF configuration inheritance applies. Configuration is inherited from instance > area > interface levels.

The "if tag..." statements can be used in distribute-list in route-policy . The matching on route tag supports operators "eq/ge/is/le". Operator "in" is not supported.

Note

When distribute-list ACL or route-policy is modified, OSPF removes all routes from the RIB, and repopulates the RIB. Due to an expected delay in the repopulation of the RIB, there could be traffic disruption.

Task ID


Task ID	Operations
ospf	read, write

Examples

The following example shows how to prevent OSPF routes from the 172.17.10.0 network from being installed if they are learned in area 0:


  RP/0/RP0/CPU0:router# configure
  RP/0/RP0/CPU0:router(config)# ipv4 access-list 3
  RP/0/RP0/CPU0:router(config-ipv4-acl)# deny 172.17.10.0 0.0.0.255 
  RP/0/RP0/CPU0:router(config-ipv4-acl)# permit any any
  !
  RP/0/RP0/CPU0:router(config)# router ospf 1 
  RP/0/RP0/CPU0:router(config-ospf)# area 0 
  RP/0/RP0/CPU0:router(config-ospf-ar)# distribute-list 3 in 
  RP/0/RP0/CPU0:router(config-ospf-ar)# interface GigabitEthernet 0/1/0/3

fast-reroute (OSPFv2)

To enable IP fast reroute loop-free alternate (LFA) computation, use the fast-reroute command in the appropriate OSPF configuration mode. To disable the IP fast reroute loop-free alternate computation, use the no form of this command.

To disable loop-free alternate computation that is enabled on a higher level, use the fast-reroute command with disable keyword.

fast-reroute {per-link | per-prefix} [disable]

no fast-reroute

Syntax Description


per-link	Enables per-link loop-free alternate computation.
per-prefix	Enables per-prefix loop-free alternate computation.
disable	(Optional) Disables loop-free alternate computation that was enabled on a higher level.

Command Default

IP fast-reroute LFA computation is disabled.

Command Modes

Area configuration

Interface configuration

Router configuration

Command History


Release	Modification
Release 5.0.0	This command was introduced and replaced the ipfrr lfa command.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

Only one mode of computation can be configured on an interface - per-link or per-prefix. Different modes of computations can be enabled on different interfaces; one set of interface using per-link and other set using per-prefix computation. Based on the outgoing interface of the primary path, per-link or per-prefix backup path will be computed.

Task ID


Task ID	Operation
ospf	read, write

Examples

This example shows how to enable per-link computation of loop-free alternates under interface POS 0/3/0/0:


RP/0/RP0/CPU0:router(config)# router ospf 1
RP/0/RP0/CPU0:router(config-ospf)# area 0
RP/0/RP0/CPU0:router(config-ospf-ar)# interface GigabitEthernet 0/3/0/0
RP/0/RP0/CPU0:router(config-ospf-ar-if)# fast-reroute per-link

This example shows how to enable per-prefix computation of loop-free alternates under area 0:


RP/0/RP0/CPU0:router#configure
RP/0/RP0/CPU0:router(config)#router ospf 1
RP/0/RP0/CPU0:router(config-ospf)#area 0
RP/0/RP0/CPU0:router(config-ospf-ar)#fast-reroute per-prefix

This example shows how to disable computation of loop-free alternates that was configured under area 0:


RP/0/RP0/CPU0:router#configure
RP/0/RP0/CPU0:router(config)#router ospf 1
RP/0/RP0/CPU0:router(config-ospf)#area 0
RP/0/RP0/CPU0:router(config-ospf-ar)#fast-reroute per-prefix 
RP/0/RP0/CPU0:router(config-ospf-ar)#interface GigabitEthernet 0/3/0/0
RP/0/RP0/CPU0:router(config-ospf-ar-if)#fast-reroute disable

fast-reroute per-link exclude interface

To excludes specified interface to be used as a backup during (IPFRR) loop-free alternate (LFA) computation, use the fast-reroute per-link exclude interface command, in the appropriate OSPF configuration mode. To disable this feature, use the no form of this command.

fast-reroute per-link exclude interface type interface-path-id

no fast-reroute per-link exclude interface type interface-path-id

Syntax Description

type

Interface type. For more information, use the question mark (?) online help function.

interface-path-id

Physical interface or virtual interface.

Note

Use the show interfaces command to see a list of all interfaces currently configured on the router.

For more information about the syntax for the router, use the question mark (?) online help function.

Command Default

No interfaces are excluded.

Command Modes

Interface configuration

Area configuration

Router configuration

Command History


Release	Modification
Release 5.0.0	This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

Task ID


Task ID	Operations
ospf	read, write

Examples

The following example shows how to exclude an interface from IP fast reroute loop-free alternate (LFA) computation:


RP/0/RP0/CPU0:router(config)# router ospf 1
RP/0/RP0/CPU0:router(config-ospf-ar-if)# fast-reroute per-link exclude interface GigabitEthernet 0/3/2/1

Related Commands


Command	Description
fast-reroute (OSPFv2)	Enables IP fast reroute loop-free alternate (LFA) computation.

fast-reroute per-prefix exclude interface (OSPFv2)

To exclude interface to be used as a backup path from fast-reroute loop-free alternate per-prefix computation, use the fast-reroute per-prefix exclude interface command in the appropriate OSPF configuration mode. To disable this feature, use the no form of this command.

fast-reroute per-prefix exclude interface type interface-path-id

no fast-reroute per-prefix exclude interface type interface-path-id

Syntax Description

type

Interface type. For more information, use the question mark (?) online help function.

interface-path-id

Physical interface or virtual interface.

Note

Use the show interfaces command to see a list of all interfaces currently configured on the router.

For more information about the syntax for the router, use the question mark (?) online help function.

Command Default

No interfaces are excluded.

Command Modes

Interface configuration

Area configuration

Router configuration

Command History


Release	Modification
Release 5.0.0	This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

Backup paths via the excluded interfaces will not be computed.

Task ID


Task ID	Operation
ospf	read, write

Examples

This example shows how to exclude interface POS0/6/0/1 from being used as a backup path:


RP/0/RP0/CPU0:router#configure 
RP/0/RP0/CPU0:router(config)#router ospf 100
RP/0/RP0/CPU0:router(config-ospf)#fast-reroute per-prefix exclude interface GigabitEthernet 0/6/0/1

fast-reroute per-prefix lfa-candidate (OSPFv2)

To add interfaces to the LFA candidate list, use the fast-reroute per-prefix lfa-candidate command in interface configuration mode. To disable this feature, use the no form of this command.

fast-reroute per-prefix lfa-candidate [interface-name]

no fast-reroute per-prefix lfa-candidate [interface-name]

Syntax Description


`interface-name`	Specifies name of the interface to add to the LFA candidate list.

Command Default

No interfaces are added to the candidate list.

Command Modes

Interface configuration

Area configuration

Router configuration

Command History


Release	Modification
Release 5.0.0	This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

Task ID


Task ID	Operation
ospf	read, write

Examples

This example shows how to add an interface to LFA candidates:


RP/0/RP0/CPU0:router#configure 
RP/0/RP0/CPU0:router(config)#router ospf 100
RP/0/RP0/CPU0:router(config-ospf)#fast-reroute per-prefix lfa-candidate interface GigabitEthernet 0/6/0/0

fast-reroute per-prefix remote-lfa (OSPFv2)

To configure fast-reroute per-prefix remote loop-free alternate (rLFA) computation for an OSPFv2 process, use the fast-reroute per-prefix remote-lfa command in the appropriate OSPF configuration mode. To disable this feature, use the no form of this command.

fast-reroute per-prefix remote-lfa {disable | maximum-cost path-cost | tunnel mpls-ldp}

no fast-reroute per-prefix remote-lfa

Syntax Description


remote-lfa	Enables remote LFA backup computation
maximum-cost `path-cost`	Sets the cost option to limit the range of remote LFAs. Range for path-cost is 1 to 4294967295.
tunnel mpls-ldp	Enables remote LFA computation using tunnel interfaces.
disable	Selectively disables remote LFA calculation under one or more areas.

Command Default

Remote LFA FRR computation is disabled.

Command Modes

Router configuration

Area configuration

Interface configuration

Command History


Release	Modification

Release 4.3.1	This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

Fast-reroute per-prefix LFA must be enabled for remote LFA to be operational. The OSPF configuration hierarchy at process level and area level are applicable for remote LFA configuration. For example, it is possible to enable remote-LFA for all OSPF areas and selectively disable (using disable keyword) the computation under one or more area.

Task ID


Task ID	Operation
ospf	read, write

Examples

This example shows how to enable fast-reroute per-prefix remote LFA computation for tunnel interfaces:


RP/0/RP0/CPU0:router(config)#router ospf 1
RP/0/RP0/CPU0:router(config-ospf)#fast-reroute per-prefix remote-lfa tunnel mpls-ldp

This example shows how to configure cost option to limit the range of remote LFAS:

RP/0/RP0/CPU0:router(config)#router ospf 1
RP/0/RP0/CPU0:router(config-ospf)#fast-reroute per-prefix remote-lfa maximum-cost 2

Related Commands

Command	Description
fast-reroute (OSPFv2)	Enables IP fast reroute loop-free alternate (LFA) computation.

fast-reroute per-prefix use-candidate-only (OSPFv2)

To restrict the backup interfaces to those that are present on the LFA candidate list, use the fast-reroute per-prefix use-candidate-only command in router OSPF configuration mode. To disable this feature, use the no form of this command.

fast-reroute per-prefix use-candidate-only [enable | disable]

fast-reroute per-prefix use-candidate-only

Syntax Description


enable	Enables backup selection from candidate-list only.
disable	Disables backup selection from candidate-list only.

Command Default

Disabled.

Command Modes

Router OSPF configuration

Command History


Release	Modification
Release 5.0.0	This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

Task ID


Task ID	Operation
ospf	read, write

Examples

This example shows how to restrict the backup interfaces to those that are present on the LFA candidate list:


RP/0/RP0/CPU0:router#configure 
RP/0/RP0/CPU0:router(config)#router ospf 100
RP/0/RP0/CPU0:router(config-ospf)#fast-reroute per-prefix use-candidate-only

flood-reduction (OSPF)

To suppress the unnecessary flooding of link-state advertisements (LSAs) in stable topologies, use the flood-reduction command in the appropriate mode. To remove this functionality from the configuration, use the no form of this command.

flood-reduction [enable | disable]

no flood-reduction [enable | disable]

Syntax Description


enable	(Optional) Turns on this functionality at a specific level.
disable	(Optional) Turns off this functionality at a specific level.

Command Default

If this command is not specified in interface configuration mode, then the interface adopts the flood reduction parameter specified by the area.

If this command is not specified in area configuration mode, then the interface adopts the flood reduction parameter specified for the process.

If this command is not specified at any level, then flood reduction is disabled.

Command Modes

Interface configuration

Area configuration

Router configuration

Command History


Release	Modification
Release 5.0.0	This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

All routers supporting the OSPF demand circuit are compatible and can interact with routers supporting flooding reduction.

Task ID


Task ID	Operations
ospf	read, write

Examples

The following example shows how to reduce the flooding of unnecessary LSAs for area 0:


  RP/0/RP0/CPU0:router# configure
  RP/0/RP0/CPU0:router(config)# router ospf 1
  RP/0/RP0/CPU0:router(config-ospf)# area 0
  RP/0/RP0/CPU0:router(config-ospf-ar)# interface GigabitEthernet 0/1/0/3
  RP/0/RP0/CPU0:router(config-ospf-ar-if)# flood-reduction

Related Commands


Command	Description
show ospf interface	Displays OSPF-related interface information.
show ospf neighbor	Displays OSPF neighbor information on an individual interface basis.

hello-interval (OSPF)

To specify the interval between consecutive hello packets that are sent on the Open Shortest Path First (OSPF) interface, use the hello-interval command in the appropriate mode. To return to the default time, use the no form of this command.

hello-interval seconds

no hello-interval

Syntax Description


`seconds`	Interval (in seconds). The value must be the same for all nodes on a specific network. Range is 1 to 65535.

Command Default

If this command is not specified in interface configuration mode, then the interface adopts the hello interval parameter specified by the area.

If this command is not specified in area configuration mode, then the interface adopts the hello interval parameter specified for the process.

If this command is not specified at any level, then the hello interval is 10 seconds (broadcast) or 30 seconds (non-broadcast).

Command Modes

Interface configuration

Area configuration

Router configuration

Virtual-link configuration

Multi-area configuration

Sham-link configuration

Command History


Release	Modification
Release 5.0.0	This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

The hello interval value is advertised in the hello packets. The shorter the hello interval, the faster topological changes are detected, but more routing traffic occurs. This value must be the same for all routers and access servers on a specific network.

Task ID


Task ID	Operations
ospf	read, write

Examples

The following example shows how to set the interval between hello packets to 15 seconds:


  RP/0/RP0/CPU0:router# configure
  RP/0/RP0/CPU0:router(config)# router ospf 1
  RP/0/RP0/CPU0:router(config-ospf)# area 0
  RP/0/RP0/CPU0:router(config-ospf-ar)# interface GigabitEthernet 0/1/0/1
  RP/0/RP0/CPU0:router(config-ospf-ar-if)# hello-interval 15

Related Commands


Command	Description
dead-interval (OSPF)	Sets the time period for which hello packets are suspended before neighbors declare the router down.

interface (OSPF)

To define the interfaces on which the Open Shortest Path First (OSPF) protocol runs, use the interface command in area configuration mode. To disable OSPF routing for interfaces, use the interface form of this command.

interface type interface-path-id

no interface type interface-path-id

Syntax Description

type

Interface type. For more information, use the question mark (?) online help function.

interface-path-id

Physical interface or virtualinterface.

Note

se the show interfaces command to see a list of all interfaces currently configured on the router.

For more information about the syntax for the router, use the question mark (?) online help function.

Command Default

When you do not specify this command in configuration mode, OSPF routing for interfaces is not enabled.

Command Modes

Area configuration

Command History


Release	Modification
Release 5.0.0	This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

Use the interface command to associate a specific interface with an area. The interface remains associated with the area even when the IP address of the interface changes.

Task ID


Task ID	Operations
ospf	read, write

Examples

The following example shows how the OSPF routing process 109 defines four OSPF areas (0, 2, 3, and 10.9.50.0), and associates an interface with each area:


  RP/0/RP0/CPU0:router# configure
  RP/0/RP0/CPU0:router(config)# router ospf 109
  RP/0/RP0/CPU0:router(config-ospf)# area 0 
  RP/0/RP0/CPU0:router(config-ospf-ar)# interface GigabitEthernet 4/0/0/3
  !
  RP/0/RP0/CPU0:router(config-ospf)# area 2
  RP/0/RP0/CPU0:router(config-ospf-ar)# interface GigabitEthernet 0/1/0/3
  !
  RP/0/RP0/CPU0:router(config-ospf)# area 3
  RP/0/RP0/CPU0:router(config-ospf-ar)# interface GigabitEthernet 3/0/0/2
  !
  RP/0/RP0/CPU0:router(config-ospf)# area 10.9.50.0
  RP/0/RP0/CPU0:router(config-ospf-ar)# interface GigabitEthernet 3/0/0/1

log adjacency changes (OSPF)

To configure the router to send a syslog message when the state of an Open Shortest Path First (OSPF) neighbor changes, use the log adjacency changes command in router configuration mode. To turn off this function, use the disable keyword. To log all state changes, use the detail keyword.

log adjacency changes {detail | disable}

Syntax Description


detail	Provides all (DOWN, INIT, 2WAY, EXSTART, EXCHANGE, LOADING, FULL) adjacency state changes.
disable	Disables sending adjacency change messages.

Command Default

The router sends a syslog message when the state of an OSPF neighbor changes.

Command Modes

Router configuration

Command History


Release	Modification
Release 5.0.0	This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

Use the log adjacency changes command to display high-level changes to the state of the peer relationship. Configure this command if you want to know about OSPF neighbor changes.

Task ID


Task ID	Operations
ospf	read, write

Examples

The following example shows how to configure the software to send a syslog message for any OSPF neighbor state changes:


  RP/0/RP0/CPU0:router# configure
  RP/0/RP0/CPU0:router(config)# router ospf 109
  RP/0/RP0/CPU0:router(config-ospf)# log adjacency changes detail

loopback stub-network

To enable advertising loopback as stub networks, use the loopback stub-network command in an appropriate configuration mode. To disable advertising loopback as stubnetworks, use the no form of this command.

loopback stub-network [enable | disable]

no loopback stub-network

Syntax Description


enable	(Optional) Enables advertising loopbacks as stub networks.
disable	(Optional) Disables advertising loopbacks as stub networks.

Command Default

By default, OSPF advertises loopbacks as stub hosts.

Command Modes

OSPF interface configuration

OSPF router configuration

OSPF area configuration

Command History


Release	Modification
Release 5.0.0	This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

In the interface submode, the command can be enabled only on loopback interfaces.

Task ID


Task ID	Operation
ospf	read, write

Examples

The following example shows how to enable advertising loopback as a stub network, under OSPF interface configuration:


RP/0/RP0/CPU0:router(config)#router ospf 100  
RP/0/RP0/CPU0:router(config-ospf)#loopback stub-network enable

Related Commands

Command	Description
show ospf interfaceDisplays Open Shortest Path First (OSPF) interface information.

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 max [threshold] [warning-only] [ignore-time value] [ignore-count value] [reset-time value]

no max-lsa max [threshold] [warning-only] [ignore-time value] [ignore-count value] [reset-time value]

Syntax Description


`max`	Maximum number of nonself-generated LSAs the OSPF process can keep in the OSPF LSBD.
`threshold`	(Optional) The percentage of the maximum LSA number, as specified by the maximum-number argument, at which a warning message is logged. The default is 75 percent.
warning-only	(Optional) Specifies that only a warning message is sent when the maximum limit for LSAs is exceeded. Disabled by default.
ignore-time `value`	(Optional) Specifies the time, in minutes, to ignore all neighbors after the maximum limit of LSAs has been exceeded. The default is 5 minutes.
ignore-count `value`	(Optional) Specifies the number of times the OSPF process can consecutively be placed into the ignore state. The default is 5 times.
reset-time `value`	(Optional) Specifies the time, in minutes, after which the ignore count is reset to zero. The default is 2 times ignore-time .

Command Default

Disabled

Command Modes

Router configuration

Command History


Release	Modification
Release 5.0.0	This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

This command allows you to protect the OSPF routing process from the large number of received LSAs that can result from a misconfiguration on another router in the OSPF domain (for example, the redistribution of a large number of IP prefixes to OSPF).

When this feature is enabled, the router keeps count of the number of all received (nonself-generated) LSAs. When the configured threshold value is reached, an error message is logged. When the configured max number of received LSAs is exceeded, the router stops accepting new LSAs.

If the count of received LSAs is higher than the configured max number after one minute, the OSPF process disables all adjacencies in the given context and clears the OSPF database. This state is called the ignore state. In this state, all OSPF packets received on all interfaces belonging to the OSPF instance are ignored and no OSPF packets are generated on its interfaces. The OSPF process remains in the ignore state for the duration of the configured ignore-time . When the ignore-time expires, the OSPF process returns to normal operation and starts building adjacencies on all its interfaces.

To prevent the OSPF instance from endlessly oscillating between its normal state and the ignore state, as a result of the LSA count immediately exceeding the max number again after it returns from the ignore state, the OSPF instance keeps a count of how many times it has been in the ignore state. This counter is called the ignore-count . If the ignore-count exceeds its configured value, the OSPF instance remains in the ignore state permanently.

To return the OSPF instance to its normal state, you must issue the clear ip ospf command. The ignore-count is reset to zero if the LSA count does not exceed the max number again during the time configured by the reset-time keyword.

If you use the warning-only keyword, the OSPF instance never enters the ignore state. When LSA count exceeds the max number, the OSPF process logs an error message and the OSPF instance continues in its normal state operation.

Task ID


Task ID	Operations
ospf	read, write

Related Commands


Command	Description
show ospf	Displays general information about Open Shortest Path First (OSPF) routing processes.

max-metric

To configure the Open Shortest Path First (OSPF) protocol to signal other networking devices not to prefer the local router as an intermediate hop in their shortest path first (SPF) calculations, use the max-metric command in router configuration mode. To disable this function, use the no form of this command.

max-metric router-lsa [external-lsa overriding metric] [include-stub] [on-proc-migration] [on-proc-restart] [on-startup] [on-switchover] [wait-for-bgp] [summary-lsa]

no max-metric router-lsa

Syntax Description

router-lsa

Always originates router link-state advertisements (LSAs) with the maximum metric.

external-lsa overriding metric

(Optional) Overrides the external-lsa metric with the max-metric value.The overriding metric argument specifies the number of in-summary-LSAs. The range is 1 to 16777215>. The default is 16711680.

include-stub

(Optional) Advertises stub links in router-LSA with the max-metric value (0xFFFF).

on-proc-migration time

(Optional) Sets the maximum metric temporarily after a process migration to originate router-LSAs with the max-metric value. The time range is 5 to 86400 seconds.

on-proc-restart time

(Optional) Sets the maximum metric temporarily after a process restart to originate router-LSAs with the max-metric value. The time range is 5 to 86400 seconds.

on-startup time

(Optional) Sets the maximum metric temporarily after a reboot to originate router-LSAs with the max-metric value. The time range is 5 to 86400 seconds.

on-switchover time

(Optional) Sets the maximum metric temporarily after a switchover to originate router-LSAs with the max-metric value. The time range is 5 to 86400 seconds.

Note

OSPF will not populate maximum metric on the router's generated LSAs, when the OSPF routing process is configured to support Nonstop Routing (NSR) or Nonstop Forwarding/Graceful restart (NSF/GR).

wait-for-bgp

(Optional) Causes OSPF to originate router LSAs with the maximum metric and allows Border Gateway Protocol (BGP) to decide when to start originating router LSAs with a normal metric instead of the maximum metric.

summary-lsa

(Optional) specifies the number of in summary-LSAs. The range is 1 to 16777215. The default is 16711680.

Command Default

Router LSAs are originated with normal link metrics.

overriding-metric :16711680

Command Modes

Router configuration

Command History


Release	Modification
Release 5.0.0	This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

Use the max-metric command to cause the software to originate router LSAs with router link metrics set to LSInfinity (0XFFFF). This feature can be useful in Internet backbone routers that run both OSPF and BGP because OSPF converges more quickly than BGP and may begin attracting traffic before BGP has converged, resulting in dropped traffic.

If this command is configured, the router advertises its locally generated router LSAs with a metric of 0XFFFF. This action allows the router to converge but not attract transit traffic if there are better, alternative paths around this router. After the specified announce-time value or notification from BGP has expired, the router advertises the local router LSAs with the normal metric (interface cost).

If this command is configured with the on-startup keyword, then the maximum metric is temporarily set only after reboot is initiated. If this command is configured without the on-startup keyword, then the maximum metric is permanently used until the configuration is removed.

If the include-stub keyword is enabled, the stub-links in the router LSA will be sent with the max-metric. If the summary-lsa keyword is enabled, all self-generated summary LSAs will have a metric set to 0xFF0000, unless the metric value is specified with the max-metric value parameter. If the external-lsa keyword is enabled, all self-generated external LSAs will have a metric set to 0xFF0000, unless the metric value is specified with the max-metric value parameter.

This command might be useful when you want to connect a router to an OSPF network, but do not want real traffic flowing through it if there are better, alternative paths. If there are no alternative paths, this router still accepts transit traffic as before.

Some cases where this command might be useful are as follows:

During a router reload, you prefer that OSPF wait for BGP to converge before accepting transit traffic. If there are no alternative paths, the router still accepts transit traffic.
A router is in critical condition (for example, it has a very high CPU load or does not have enough memory to store all LSAs or build the routing table).
When you want to gracefully introduce or remove a router to or from the network.
When you have a test router in a lab, connected to a production network.

Note

For older OSPF implementations (RFC 1247), router links in received router LSAs with a metric and cost of LSInfinity are not used during SPF calculations. Hence, no transit traffic is set to the routers originating such router LSAs.

Task ID


Task ID	Operations
ospf	read, write

Examples

The following example shows how to configure OSPF to originate router LSAs with the maximum metric until BGP indicates that it has converged:


RP/0/RP0/CPU0:router# configure
RP/0/RP0/CPU0:router(config)# router ospf 109
RP/0/RP0/CPU0:router(config-ospf)# max-metric router-lsa on-startup wait-for-bgp

maximum interfaces (OSPF)

To limit the number of interfaces that can be configured for an Open Shortest Path First (OSPF) process, use the maximum interfaces command in the appropriate mode. To return to the default limit, use the no form of this command.

maximum interfaces number-interfaces

no maximum interfaces

Syntax Description


`number-interfaces`	Number of interfaces. Range is 1 to 4294967295.

Command Default

If the command is not specified, the default is 1024.

Command Modes

Router configuration

Command History


Release	Modification
Release 5.0.0	This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

Use the maximum interface command to increase or decrease the limit on the number of interfaces configured for an OSPF process.

You cannot configure a limit lower than the number of interfaces currently configured for the OSPF process. To lower the limit, remove interfaces from the OSPF configuration until the number of configured interfaces is at or below the desired limit. You may then apply the new, lower limit.

Task ID


Task ID	Operations
ospf	read, write

Examples

This example shows how to configure a maximum interface limit of 1500 on a router:


  RP/0/RP0/CPU0:router# configure
  RP/0/RP0/CPU0:router(config)# router ospf 109
  RP/0/RP0/CPU0:router(config-ospf)# maximum interfaces 1500

Related Commands


Command	Description
show ospf interface	Displays OSPF interface information.

maximum paths (OSPF)

To control the maximum number of parallel routes that the Open Shortest Path First (OSPF) protocol can support, use the maximum paths command in an appropriate configuration mode. To remove the maximum paths command from the configuration file and restore the system to its default condition with respect to the routing protocol, use the no form of this command.

maximum paths maximum-routes-number

no maximum paths

Syntax Description

maximum-routes-number

Maximum number of parallel routes that OSPF can install in a routing table. Range is 1 to 64.

Note

The maximum number of paths that can be configured is 64.

Command Default

64 paths

Command Modes

Router configuration

Command History


Release	Modification
Release 5.0.0	This command was introduced.
Release 6.1.2	This command was modified. The maximum number of paths that can be configured has increased from 32 to 64 paths. The command default has increased from 32 to 64 paths.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

The default value for maximum-path depends on the platform supported maximum-path value. Any custom value you define for the maximum-path parameter must be within the maximum value supported by platform. The configuration will be rejected if the value you have specified is more then what the platform supports.

When the maximum number of parallel routes is reduced, all existing paths are pruned and paths reinstalled at the new maximum number. During this route-reduction period, you may experience some packet loss for a few seconds. This may impact route traffic.

Task ID


Task ID	Operations
ospf	read, write

Examples

The following example shows how to allow a maximum of two paths to a destination:


RP/0/RP0/CPU0:router# configure
RP/0/RP0/CPU0:router(config)# router ospf 109
RP/0/RP0/CPU0:router(config-ospf)# maximum paths 2

maximum redistributed-prefixes (OSPF)

To limit the aggregate number of prefixes that can be redistributed into an Open Shortest Path First (OSPF) process, use the maximum redistributed-prefix command in the appropriate mode. To return to the default limit, use the no form of this command.

maximum redistributed-prefixes maximum [threshold-value] [warning-only]

no maximum redistributed-prefixes

Syntax Description


`maximum`	Number of routes. Range is 1 to 4294967295.
`threshold-value`	(Optional) Threshold value (as a percentage) at which to generate a warning message. Range is 1 to 100.
warning-only	(Optional) Gives only a warning when the limit is exceeded.

Command Default

If the command is not specified, the default is 10000.

The threshold value defaults to 75 percent.

Command Modes

Router configuration

Command History


Release	Modification
Release 5.0.0	This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

Use the maximum redistributed-prefixes command to increase or decrease the maximum number of prefixes (also referred to as routes) redistributed for an OSPF process.

If the maximum value is less than the existing number of routes, existing routes remain configured, but no new routes are redistributed.

Task ID


Task ID	Operations
ospf	read, write

Examples

The following example shows how to configure a maximum number of routes that can be redistributed for an OSPF routing process:


  RP/0/RP0/CPU0:router# configure
  RP/0/RP0/CPU0:router(config)# router ospf 109
  RP/0/RP0/CPU0:router(config-ospf)# maximum redistributed-prefixes 15000

Related Commands


Command	Description
show ospf routes	Displays the OSPF topology table.

message-digest-key

To specify a key used with Open Shortest Path First (OSPF) Message Digest 5 (MD5) authentication, use the message-digest-key command in the appropriate mode. To remove an old MD5 key, use the no form of this command.

message-digest-key key-id md5 {key | clear key | encrypted key}

no message-digest-key key-id

Syntax Description


`key-id`	Key number. Range is 1 to 255.
md5	Enables OSPF MD5 authentication.
`key`	Alphanumeric string of up to 16 characters.
clear	Specifies that the key be clear text.
encrypted	Specifies that the key be encrypted using a two-way algorithm.

Command Default

If this command is not specified in interface configuration mode, then the interface adopts the message digest key parameter specified by the area.

If this command is not specified in area configuration mode, then the interface adopts the message digest key parameter specified for the process.

If this command is not specified at any level, then OSPF MD5 authentication is disabled.

Command Modes

Interface configuration

Area configuration

Router configuration

Virtual-link configuration

Multi-area configuration

Sham-link configuration

Command History


Release	Modification
Release 5.0.0	This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

Usually, one key individual interface is used to generate authentication information when packets are sent and to authenticate incoming packets. The same key identifier on the neighbor router must have the same key value.

For authentication to be enabled, you must configure the message-digest-key command together with the authentication command and its message-digest keyword. Both the message-digest-key and authentication commands can be inherited from a higher configuration level.

The process of changing keys is as follows. Suppose the current configuration is:


  interface GigabitEthernet 0/3/0/2
   message-digest-key 100 md5 OLD

You change the configuration to the following:


  interface GigabitEthernet 0/3/0/2
   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 after 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 ospf message-digest-key 100

Then, only key 101 is used for authentication on interface 1.

We recommend that you not keep more than one key individual 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

The MD5 key is always stored in encrypted format on the router. The clear and encrypted keywords inform the router whether the value that is entered is encrypted or unencrypted.

Task ID


Task ID	Operations
ospf	read, write

Examples

The following example shows how to set a new key 19 with the password 8ry4222 :


  RP/0/RP0/CPU0:router# configure
  RP/0/RP0/CPU0:router(config)# router ospf 109
  RP/0/RP0/CPU0:router(config-ospf)# area 0 
  
  RP/0/RP0/CPU0:router(config-ospf-ar)# interface GigabitEthernet 0/1/0/1
  RP/0/RP0/CPU0:router(config-ospf-ar-if)# message-digest-key 19 md5 8ry4222

Related Commands


Command	Description
area (OSPF)	Configures an OSPF area.
authentication (OSPF)	Enables plain text, MD5 authentication, or null authentication for an OSPF interface.
default-cost (OSPF)	Enables authentication for an OSPF area.

mpls ldp auto-config (OSPF)

To enable Label Distribution Protocol (LDP)-Interior Gateway Protocol (IGP) interface automatic configuration, use the mpls ldp auto-config command in the appropriate mode. To disable LDP-IGP interface automatic configuration, use the no form of this command.

mpls ldp auto-config

no mpls ldp auto-config

Command Default

LDP-IGP interface automatic configuration is disabled for OSPF.

Command Modes

Interface configuration

Area configuration

Router configuration

Command History


Release	Modification
Release 5.0.0	This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

Task ID


Task ID	Operations
ospf	read, write

Examples

The following example shows how to enable LDP-IGP interface automatic configuration:


  RP/0/RP0/CPU0:router# configure
  RP/0/RP0/CPU0:router(config)# router ospf o1
  RP/0/RP0/CPU0:router(config-ospf)# mpls ldp auto-config

mpls ldp sync (OSPF)

To enable Label Distribution Protocol (LDP)-Interior Gateway Protocol (IGP) synchronization, use the mpls ldp sync command in the appropriate mode. To disable LDP-IGP synchronization, use the no form of this command.

mpls ldp sync [disable]

no mpls ldp sync

Syntax Description


disable	(Optional) Disables MPLS LDP synchronization from within the OSPF interface and area configuration submodes only. For the OSPF router configuration mode, use the no form of the command.

Command Default

LDP-IGP synchronization is disabled for OSPF.

Command Modes

Interface configuration

Area configuration

Router configuration

Command History


Release	Modification
Release 5.0.0	This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

Task ID


Task ID	Operations
ospf	read, write

Examples

The following example shows how to enable LDP-IGP synchronization:


  RP/0/RP0/CPU0:router# configure
  RP/0/RP0/CPU0:router(config)# router ospf o1
  RP/0/RP0/CPU0:router(config-ospf)# mpls ldp sync

mpls ldp sync-igp-shortcuts

To configure and enable Label Distribution Protocol- Interior Gateway Protocol (LDP-IGP) synchronization on Multiprotocol Label Switching (MPLS) shortcuts (auto-route announced tunnels) only, use the mpls ldp sync-igp-shortcuts command in the appropriate OSPF configuration mode. To disable the use of LDP-IGP synchronization on MPLS shortcuts, use the no form of this command.

mpls ldp sync-igp-shortcuts [disable]

no mpls ldp sync-igp-shortcuts

Syntax Description


disable	(Optional) Disables MPLS LDP synchronization with IGP shortcuts from within the OSPF interface and area configuration submodes only. For the OSPF router configuration mode, use the no form of the command.

Command Default

LDP-IGP synchronization is disabled on MPLS tunnels.

Command Modes

OSPF interface configuration

OSPF router configuration

OSPF area configuration

Command History


Release	Modification
Release 5.0.0	This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

When mpls ldp sync-igp-shortcuts is configured at a higher mode (area or instance level), you can selectively disable LDP-IGP synchronization on specific interfaces or areas by using the disable form of the command.

Task ID


Task ID	Operations
ospf	read, write

Examples

The following example shows how to enable LDP-IGP synchronization shortcuts under OSPF interface configuration, using the mpls ldp sync-igp-shortcuts command on a tunnel-te interface. However, the command applies to all interfaces under the applicable configuration mode.


RP/0/RP0/CPU0:router(config)# router ospf 100 
RP/0/RP0/CPU0:router(config-ospf)# area 0  
RP/0/RP0/CPU0:router(config-ospf-ar)# interface tunnel-te 1 
RP/0/RP0/CPU0:router(config-ospf-ar-if)# mpls ldp sync-igp-shortcuts

When mpls ldp sync-igp-shortcuts is configured at a higher mode (area or instance level), you can selectively disable LDP-IGP synchronization on specific interfaces or areas by using the disable form of the command:

The following example shows how to enable the use of LDP-IGP synchronization across all interfaces in all areas except area 10:


RP/0/RP0/CPU0:router(config)# router ospf foo 
RP/0/RP0/CPU0:router(config-ospf)# mpls ldp sync-igp-shortcuts 
RP/0/RP0/CPU0:router(config-ospf)# area 10 
RP/0/RP0/CPU0:router(config-ospf-ar)# mpls ldp sync-igp-shortcuts disable

Related Commands


Command	Description
mpls ldp sync (OSPF)	Enables Label Distribution Protocol (LDP)-Interior Gateway Protocol (IGP) synchronization.

mpls traffic-eng ldp-sync-update (OSPF)

To enable Label Distribution Protocol (LDP)-OSPF Type 1 and Type 10 link-state advertisement (LSA) synchronization, use the mpls traffic-eng ldp-sync-update command in the appropriate mode. To disable LDP-LSA synchronization, use the no form of this command.

mpls traffic-eng ldp-sync-update

no mpls traffic-eng ldp-sync-update

Command Default

LDP-LSA synchronization is disabled for OSPF.

Command Modes

Router configuration

Interface configuration

Area configuration

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

Whenever there is a change in the network (link failure, addition, new nodes, cost change or router cost out), the Type 1 and Type 10 LSA should be in sync. In most of the cases Type 1 and Type 10 are in sync, however it was observed that when IGP-LDP sync is not established, the Type 1 indicates the high cost while the Type 10 shows the normal cost. Use the mpls traffic-eng ldp-sync-update command to synchronize Label Distribution Protocol (LDP)-OSPF Type 1 and Type 10 link-state advertisement (LSA).

Task ID


Task ID	Operations
ospf	read, write

Examples

The following example shows how to enable LDP-IGP OSPF Type 1 and Type 10 link-state advertisement (LSA) synchronization:


  RP/0/RP0/CPU0:router# configure
  RP/0/RP0/CPU0:router(config)# router ospf o1
  RP/0/RP0/CPU0:router(config-ospf)# mpls traffic-eng ldp-sync-update

mtu-ignore (OSPF)

To prevent Open Shortest Path First (OSPF) from checking whether neighbors are using the same maximum transmission unit (MTU) on a common interface when exchanging database descriptor (DBD) packets, use the mtu-ignore command in the appropriate mode. To reset to default, use the no form of this command.

mtu-ignore [disable | enable]

no mtu-ignore

Syntax Description


disable	(Optional) Enables checking for whether OSPF neighbors are using the MTU on a common interface.
enable	(Optional) Disables checking for whether OSPF neighbors are using the MTU on a common interface.

Command Default

The default is mtu-ignore with no keywords, which disables MTU checking.

If this command is not specified in interface configuration mode,

then the interface adopts the MTU ignore parameter specified by the area.

If this command is not specified in area configuration mode,

then the interface adopts the MTU ignore parameter specified for the process.

If this command is not specified at any level,

then OSPF checks the MTU received from neighbors when exchanging DBD packets.

Command Modes

Interface configuration

Area configuration

Router configuration

Multi-area configuration

Command History


Release	Modification
Release 5.0.0	This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

OSPF checks whether OSPF 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 MTU configured on the incoming interface, OSPF adjacency is not established.

The keywords, disable and enable , do not need to be used. If no keywords are used, the mtu-ignore command disables MTU checking. You can then use the no mtu-ignore command to activate MTU checking.

Task ID


Task ID	Operations
ospf	read, write

Examples

The following example shows how to disable MTU mismatch detection on receiving DBD packets:


  RP/0/RP0/CPU0:router# configure
  RP/0/RP0/CPU0:router(config)# router ospf 109
  RP/0/RP0/CPU0:router(config-ospf)# area 0 
  RP/0/RP0/CPU0:router(config-ospf-ar)# interface GigabitEthernet 0/1/0/3
  RP/0/RP0/CPU0:router(config-ospf-ar-if)# mtu-ignore

multi-area-interface

To enable multiple adjacencies for different Open Shortest Path First (OSPF) areas and enter multi-area interface configuration mode, use the multi-area-interface command in the area configuration mode. To reset to the default, use the no form of this command.

multi-area-interface type interface-path-id

no multi-area-interface type interface-path-id

Syntax Description

type

Interface type. For more information, use the question mark (?) online help function.

interface-path-id

Physical interface or virtual interface.

Note

Use the show interfaces command to see a list of all interfaces currently configured on the router.

For more information about the syntax for the router, use the question mark (?) online help function.

Command Default

An OSPF network is enabled for one area only.

Command Modes

Area configuration

Command History


Release	Modification
Release 5.0.0	This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

Use the multi-area-interface command to enable area border routers (ABRs) to establish multiple adjacencies for different OSPF areas.

Each multiple area adjacency is announced as a point-to-point unnumbered link in the configured area. This point-to-point link provides a topological path for that area. The first or primary adjacency using the link advertises the link consistent with draft-ietf-ospf-multi-area-adj-06.txt.

You can configure multi-area adjacency on any interface where only two OSF speakers are attached. In the case of native broadcast networks, the interface must be configured as an OPSF point-to-point type using the network point-to-point command to enable the interface for a multi-area adjacency.

Task ID


Task ID	Operations
ospf	read, write

Examples

The following example shows how to enable multiple area adjacency for OSPF 109:


RP/0/RP0/CPU0:router# configure
RP/0/RP0/CPU0:router(config)# router ospf 109
RP/0/RP0/CPU0:router(config-ospf)# area 0
RP/0/RP0/CPU0:router(config-ospf-ar)# interface GigabitEthernet 0/1/0/3
RP/0/RP0/CPU0:router(config-ospf-ar-if)# area 1
RP/0/RP0/CPU0:router(config-ospf-ar)# multi-area-interface GigabitEthernet 0/1/0/3
RP/0/RP0/CPU0:router(config-ospf-ar-mif)# ?
  
    authentication       Enable authentication
    authentication-key   Authentication password (key)
    commit               Commit the configuration changes to running
    cost                 Interface cost
    database-filter      Filter OSPF LSA during synchronization and flooding
    dead-interval        Interval after which a neighbor is declared dead
    describe             Describe a command without taking real actions
    distribute-list      Filter networks in routing updates
    do                   Run an exec command
    exit                 Exit from this submode
    hello-interval       Time between HELLO packets
    message-digest-key   Message digest authentication password (key)
    mtu-ignore           Enable/Disable ignoring of MTU in DBD packets
    no                   Negate a command or set its defaults
    packet-size          Customize size of OSPF packets upto MTU
    pwd                  Commands used to reach current submode
    retransmit-interval  Time between retransmitting lost link state advertisements
    root                 Exit to the global configuration mode
    show                 Show contents of configuration
    transmit-delay       Estimated time needed to send link-state update packet
RP/0/RP0/CPU0:router(config-ospf-ar-mif)#

Related Commands


Command	Description
show ospf interface	Displays OSPF interface information.

neighbor (OSPF)

To configure Open Shortest Path First (OSPF) routers interconnecting to nonbroadcast networks, use the neighbor command in interface configuration mode. To remove a configuration, use the no form of this command.

neighbor ip-address [cost number] [priority number] [poll-interval seconds]

no neighbor ip-address [cost number] [priority number] [poll-interval seconds]

Syntax Description


`ip-address`	Interface IP address of the neighbor.
cost `number`	(Optional) Assigns a cost to the neighbor, in the form of an integer from 1 to 65535. Neighbors with no specific cost configured assume the cost of the interface, based on the cost command. On point-to-multipoint interfaces, cost number is the only keyword and argument combination that works. The cost keyword does not apply to nonbroadcast multiaccess (NBMA) networks.
priority `number`	(Optional) Specifies an 8-bit number indicating the router priority value of the nonbroadcast neighbor associated with the IP address specified. The priority keyword does not apply to point-to-multipoint interfaces.
poll-interval `seconds`	(Optional) Specifies an unsigned integer value (in seconds) reflecting the poll interval. RFC 1247 recommends that this value be much larger than the hello interval. The poll-interval keyword does not apply to point-to-multipoint interfaces.

Command Default

No configuration is specified.

priority number : 0

poll-interval seconds : 120 seconds (2 minutes)

Command Modes

Interface configuration

Command History


Release	Modification
Release 5.0.0	This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

You must include one neighbor entry in the 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 are sent at a reduced rate called the poll interval.

When the router 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, the DR and BDR start sending hello packets to all neighbors to form adjacencies.

To filter all outgoing OSPF link-state advertisement (LSA) packets for the neighbor, use the neighbor database-filter all out command.

Task ID


Task ID	Operations
ospf	read, write

Examples

The following example shows how to declare a router at address 172.16.3.4 on a nonbroadcast network, with a priority of 1 and a poll interval of 180 seconds:


  RP/0/RP0/CPU0:router(config-ospf-ar-if)# neighbor 172.16.3.4 priority 1 poll-interval 180

The following example illustrates a network with nonbroadcast:


  RP/0/RP0/CPU0:router# configure
  RP/0/RP0/CPU0:router(config)# interface GigabitEthernet1/0/0/3
  RP/0/RP0/CPU0:router(config-if)# ip address 172.16.3.10 255.255.255.0
  
  RP/0/RP0/CPU0:router(config)# router ospf 1
  RP/0/RP0/CPU0:router(config-ospf)# area 0
  RP/0/RP0/CPU0:router(config-ospf-ar)# interface GigabitEthernet1/0/0/3
  RP/0/RP0/CPU0:router(config-ospf-ar-if)# network nonbroadcast
  RP/0/RP0/CPU0:router(config-ospf-ar-if)# neighbor 172.16.3.4 priority 1 poll-interval 180
  RP/0/RP0/CPU0:router(config-ospf-ar-if)# neighbor 172.16.3.5 cost 10 priority 1 poll-interval 180
  RP/0/RP0/CPU0:router(config-ospf-ar-if)# neighbor 172.16.3.6 cost 15 priority 1 poll-interval 180
  RP/0/RP0/CPU0:router(config-ospf-ar-if)# neighbor 172.16.3.7 priority 1 poll-interval 180

Related Commands


Command	Description
neighbor database-filter all out	Filters all outgoing LSAs to an OSPF neighbor.
network (OSPF)	Configures the OSPF network type to a type other than the default for a given medium.
priority (OSPF)	Sets the router priority, which helps determine the designated router for this network.

neighbor database-filter all out

To filter all outgoing link-state advertisements (LSAs) to an Open Shortest Path First (OSPF) neighbor, use the neighbor database-filter all out command in interface configuration mode. To restore the forwarding of LSAs to the neighbor, use the no form of this command.

neighbor ip-address database-filter all out

no neighbor ip-address database-filter all out

Syntax Description


`ip-address`	IP address of the neighbor to which outgoing LSAs are blocked.

Command Default

Instead of all outgoing LSAs being filtered to the neighbor, they are flooded to the neighbor.

Command Modes

Interface configuration

Command History


Release	Modification
Release 5.0.0	This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

Use the neighbor database-filter all out command to filter all outgoing OSPF LSA packets during synchronization and flooding for point-to-multipoint neighbors on nonbroadcast networks. More neighbor options are available with the neighbor command.

Task ID


Task ID	Operations
ospf	read, write

Examples

The following example shows how to prevent flooding of OSPF LSAs from point-to-multipoint networks to the neighbor at IP address 10.2.3.4:


  RP/0/RP0/CPU0:router# configure
  RP/0/RP0/CPU0:router(config)# router ospf 1
  RP/0/RP0/CPU0:router(config-ospf)# area 0
  RP/0/RP0/CPU0:router(config-ospf-ar)# interface GigabitEthernet1/0/0/3
  RP/0/RP0/CPU0:router(config-ospf-ar-if)# neighbor 10.2.3.4 database-filter all out

Related Commands


Command	Description
neighbor (OSPF)	Configures OSPF routers interconnecting to nonbroadcast networks.

network (OSPF)

To configure the Open Shortest Path First (OSPF) network type to a type other than the default for a given medium, use the network command in the appropriate mode. To return to the default value, use the no form of this command.

network {broadcast | non-broadcast | {point-to-multipoint [non-broadcast] | point-to-point}}

no network

Syntax Description


broadcast	Sets the network type to broadcast.
non-broadcast	Sets the network type to nonbroadcast multiaccess (NBMA).
point-to-multipoint	Sets the network type to point-to-multipoint.
non-broadcast	(Optional) Sets the point-to-multipoint network to be nonbroadcast. If you use this keyword, the neighbor command is required.
point-to-point	Sets the network type to point-to-point.

Command Default

If this command is not specified in interface configuration mode, then the interface adopts the network parameter specified by the area.

If this command is not specified in area configuration mode, then the interface adopts the network parameter specified for the process.

If this command is not specified at any level, then the OSPF network type is the default of the given medium.

POS interfaces default to point-to-point and GigabitEthernt and TenGigEthernet interfaces default to broadcast.

Command Modes

Interface configuration

Area configuration

Router configuration

Command History


Release	Modification
Release 5.0.0	This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

Configuring NBMA networks as either broadcast or nonbroadcast assumes that there are virtual circuits from every router to every router or fully meshed network. 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 go through the router that has virtual circuits to both routers.

If this command is issued on an interface that does not allow it, this command is ignored.

OSPF has two features related to point-to-multipoint networks. One feature applies to broadcast networks; the other feature applies to nonbroadcast networks:

On point-to-multipoint, broadcast networks, you can use the neighbor command, and you must specify a cost to that neighbor.
On point-to-multipoint, nonbroadcast networks, you must use the neighbor command to identify neighbors. Assigning a cost to a neighbor is optional.

Task ID


Task ID	Operations
ospf	read, write

Examples

The following example shows how to configure the OSPF network as a nonbroadcast network:


  RP/0//CPU0:router# configure
  RP/0//CPU0:router(config)# router ospf 1
  RP/0//CPU0:router(config-ospf)# area 0
  RP/0//CPU0:router(config-ospf-ar)# interface GigabitEthernet 0/1/0/3
  RP/0//CPU0:router(config-ospf-ar-if)# network non-broadcast
  RP/0//CPU0:router(config-ospf-ar-if)# neighbor 172.16.3.4 priority 1 poll-interval 180

Related Commands


Command	Description
neighbor (OSPF)	Configures OSPF routers interconnecting to nonbroadcast networks.

nsf (OSPF)

To configure nonstop forwarding (NSF) for the Open Shortest Path First (OSPF) protocol, use the nsf command in the appropriate mode. To remove this command from the configuration file and restore the system to its default condition, use the no form of this command.

nsf {cisco [enforce global] | ietf [helper disable]}

no nsf {cisco [enforce global] | ietf [helper disable]}

Syntax Description


cisco	Enables Cisco Nonstop Forwarding.
enforce global	(Optional) Cancels NSF restart when non-NSF network device neighbors are detected.
ietf	Enables Internet Engineering Task Force (IETF) graceful restart.
helper disable	(Optional) Disables router helper support.

Command Default

NSF is disabled.

Command Modes

Router configuration

Command History


Release	Modification
Release 5.0.0	This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

The NSF feature allows for the forwarding of data packets to continue along known routes while routing protocol information (such as OSPF) is being restored following a switchover.

Use the nsf command if the router is expected to perform NSF during restart. To experience the full benefits of this feature, configure all neighboring routers with NSF.

When this command is used without the optional cisco enforce global keywords and non-NSF neighbors are detected, the NSF restart mechanism aborts on the interfaces of those neighbors and functions properly on others.

When this command is used with the optional cisco enforce global keywords and non-NSF neighbors are detected, NSF restart is canceled for the entire OSPF process.

IETF graceful restart provides an NSF mechanism to allow data traffic to flow seamlessly with no packet drops during the transient period when OSPF attempts to recover after a process restart or RP failover, within the guidelines of RFC 3623.

By default, neighbors in helper mode listen to both the NSF Cisco- and NSF IETF-type LSAs. The nsf command enables one type of mechanism that would undergo an RP failover or, anticipating an OSPF process restart. If the cisco or ietf keyword is not entered, NSF is not enabled, irrespective of neighbors in listening mode for both NSF Cisco and NSF IETF.

Task ID


Task ID	Operations
ospf	read, write

Examples

The following example shows how to cancel NSF restart for the entire OSPF process if non-NSF neighbors are detected on any network interface during restart:


  RP/0/RP0/CPU0:router# configure
  RP/0/RP0/CPU0:router(config)# router ospf 1
  RP/0/RP0/CPU0:router(config-ospf)# nsf cisco enforce global

nsf flush-delay-time (OSPF)

To configure the maximum time allowed for nonstop forwarding (NSF) external route queries for the Open Shortest Path First (OSPF) protocol, use the nsf flush-delay-time command in the appropriate mode. To remove this command from the configuration file and restore the system to its default condition, use the no form of this command.

nsf flush-delay-time seconds

no nsf flush-delay-time seconds

Syntax Description


`seconds`	Length of time (in seconds) allowed for NSF external route queries. Range is 1 to 3600 seconds.

Command Default

seconds : 300

Command Modes

Router configuration

Command History


Release	Modification
Release 5.0.0	This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

Task ID


Task ID	Operations
ospf	read, write

Examples

The following example shows how to configure the maximum time for NSF to learn external routes for OSPF at 60 seconds:


  RP/0/RP0/CPU0:router# configure
  RP/0/RP0/CPU0:router(config)# router ospf 1
  RP/0/RP0/CPU0:router(config-ospf)# nsf flush-delay-time 60

nsf interval (OSPF)

To configure the minimum time between consecutive nonstop forwarding (NSF) restart attempts for the Open Shortest Path First (OSPF) protocol, use the nsf interval command in the appropriate mode. To remove this command from the configuration file and restore the system to its default condition, use the no form of this command.

nsf interval seconds

no nsf interval seconds

Syntax Description


`seconds`	Length of time (in seconds) between consecutive restart attempts. Range is 90 to 3600 seconds.

Command Default

seconds : 90

Command Modes

Router configuration

Command History


Release	Modification
Release 5.0.0	This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

When you use the nsf interval command, the OSPF process must be up for at least 90 seconds before OSPF attempts to perform an NSF restart.

Task ID


Task ID	Operations
ospf	read, write

Examples

The following example shows how to configure the minimum time between consecutive NSF restart attempts at 120 seconds:


  RP/0/RP0/CPU0:router# configure
  RP/0/RP0/CPU0:routerr(config)# router ospf 1
  RP/0/RP0/CPU0:router(config-ospf)# nsf interval 120

nsf lifetime (OSPF)

To configure the maximum time that routes are held in the Routing Information Base (RIB) following an Open Shortest Path First (OSPF) process restart, use the nsf lifetime command in the appropriate mode. To remove this command from the configuration file and restore the system to its default condition, use the no form of this command.

nsf lifetime seconds

no nsf lifetime seconds

Syntax Description


`seconds`	The length of time (in seconds) that routes are held in the RIB. Range is 90 to 3600 seconds.

Command Default

seconds : 95

Command Modes

Router configuration

Command History


Release	Modification
Release 5.0.0	This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

When you use this command, the OSPF process must reconverge within the maximum length of time configured. If the convergence exceeds this length of time, routes are purged from RIB and nonstop forwarding (NSF) restart may fail.

Task ID


Task ID	Operations
ospf	read, write

Examples

The following example shows how to configure the maximum lifetime for OSPF NSF at 120 seconds:


  RP/0/RP0/CPU0:router# configure
  RP/0/RP0/CPU0:router(config)# router ospf 1
  RP/0/RP0/CPU0:router(config-ospf)# nsf lifetime 120

nssa (OSPF)

To configure an area as a not-so-stubby area (NSSA), use the nssa command in area configuration mode. To remove the NSSA distinction from the area, use the no form of this command.

nssa [no-redistribution] [default-information-originate [metric metric-value] [metric-type type-value]] [no-summary]

no nssa

Syntax Description


no-redistribution	(Optional) Imports routes only into the normal areas, but not into the NSSA area, by the redistribute command when the router is an NSSA Area Border Router (ABR).
default-information- originate	(Optional) Generates a Type 7 default into the NSSA area. This keyword takes effect only on an NSSA ABR or NSSA Autonomous System Boundary Router (ASBR).
metric `metric-value`	(Optional) Specifies the metric used for generating the default route. If you omit a value and do not specify a value using the defaultmetric command, the default metric value is 10. Range is 1 to 16777214.
metric-type `type-value`	(Optional) Specifies the 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
no-summary	(Optional) Prevents an ABR from sending summary link advertisements into the NSSA.

Command Default

No NSSA area is defined.

Command Modes

Area configuration

Command History


Release	Modification
Release 5.0.0	This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

An NSSA does not flood Type 5 external LSAs from the core into the area, but can import autonomous system external routes in a limited fashion within the area.

Task ID


Task ID	Operations
ospf	read, write

Examples

The following example shows how to configure area 1 as an NSSA area:


  RP/0/RP0/CPU0:router# configure
  RP/0/RP0/CPU0:router(config)# router ospf 1
  RP/0/RP0/CPU0:router(config-ospf)# area 1
  RP/0/RP0/CPU0:router(config-ospf-ar)# nssa

ospf name-lookup

To configure the Open Shortest Path First (OSPF) protocol to look up Domain Name System (DNS) names, use the ospf name-lookup command in XR Config mode. To disable this function, use the no form of this command.

ospf name-lookup

no ospf name-lookup

Command Default

Routers are displayed by router ID or neighbor ID.

Command Modes

XR Config

Command History


Release	Modification
Release 5.0.0	This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

Use the ospf name-lookup command to easily identify a router when executing all OSPF show command displays. The router is displayed by name rather than by its router ID or neighbor ID.

Task ID


Task ID	Operations
ospf	read, write

Examples

The following example shows how to configure OSPF to identify a router by name:


  RP/0/RP0/CPU0:router# configure
  RP/0/RP0/CPU0:router(config)# ospf name-lookup

packet-size (OSPF)

To configure the size of Open Shortest Path First (OSPF) packets up to the size specified by the maximum transmission unit (MTU), use the packet-size command in the appropriate configuration mode. To disable this function and reestablish the default packet size, use the no form of this command.

packet-size bytes

no packet-size

Syntax Description


`bytes`	Size, in bytes. Range is 576 to 10000 bytes.

Command Default

If the command is not specified, the default packet size is either the interface IP MTU size (if that is lower than 9000 bytes) or 9000 bytes.

Command Modes

Router configuration

Area configuration

Interface configuration

Multi-area configuration

Command History


Release	Modification
Release 5.0.0	This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

Use the packet-size command to customize the size of OSPF packets. The OSPF protocol compares the packet size and the MTU size and uses the lower packet size value.

If the command is not configured, the default packet size is equal to the interface IP MTU size (if that is lower than 9000 bytes) or 9000 bytes. For example, if the interface IP MTU size is 1500 bytes, OSPF uses packet size of 1500 bytes on the interface because the byte size is lower than 9000 bytes. If the interface IP MTU size is 9500 bytes, OSPF uses packet size of 9000 bytes on the interface because the byte size exceeds 9000 bytes. The interface IP MTU size depends on the interface and the platform. In most cases, the default interface IP MTU value will be lower than 9000 bytes.

Task ID


Task ID	Operations
ospf	read, write

Examples

The following example shows how to configure the packet size on an interface:


RP/0/RP0/CPU0:router# configure
RP/0/RP0/CPU0:router(config)# router ospf 1
RP/0/RP0/CPU0:router(config-ospf)# area 0
RP/0/RP0/CPU0:router(config-ospf-ar)# interface GigabitEthernet 1/0/0/2
RP/0/RP0/CPU0:router(config-ospf-ar-if)# packet-size 3500

passive (OSPF)

To suppress the sending of Open Shortest Path First (OSPF) protocol operation on an interface, use the passive command in the appropriate mode. To remove the passive configuration, use the no form of this command.

passive [disable | enable]

no passive

Syntax Description


disable	(Optional) Sends OSPF updates.
enable	(Optional) Disables sending OSPF updates.

Command Default

If this command is not specified in interface configuration mode, then the interface adopts the passive parameter specified by the area.

If this command is not specified in area configuration mode, then the interface adopts the passive parameter specified for the process.

If this command is not specified at any level, then the passive parameter is disabled and OSPF updates are sent on the interface.

Command Modes

Interface configuration

Area configuration

Router configuration

Command History


Release	Modification
Release 5.0.0	This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

OSPF routing information is neither sent nor received through the specified interface. The interface appears as a stub network in the OSPF router (Type 1) link-state advertisement (LSA).

Task ID


Task ID	Operations
ospf	read, write

Examples

The following example shows that GigabitEthernet interface 1/0/0/2 reduces OSPF updates because passive mode is enabled; however, GigabitEthernet interface 0/1/0/3 receives normal OSPF traffic flow:


  RP/0/RP0/CPU0:router# configure
  RP/0/RP0/CPU0:router(config)# router ospf 1
  RP/0/RP0/CPU0:router(config-ospf)# area 0
  RP/0/RP0/CPU0:router(config-ospf-ar)# interface GigabitEthernet1/0/0/2
  RP/0/RP0/CPU0:router(config-ospf-ar-if)# passive
  RP/0/RP0/CPU0:router(config-ospf-ar-if)# exit
  RP/0/RP0/CPU0:router(config-ospf-ar)# interface GigabitEthernet1/0/0/3
  RP/0/RP0/CPU0:router(config-ospf-ar-if)# end

priority (OSPF)

To set the router priority for an interface, which helps determine the designated router for an Open Shortest Path First (OSPF) link, use the priority command in the appropriate mode. To return to the default value, use the no form of this command.

priority value

no priority value

Syntax Description


`value`	8-bit unsigned integer indicating the router priority value. Range is 0 to 255.

Command Default

If this command is not specified in interface configuration mode, then the interface adopts the priority parameter specified by the area.

If this command is not specified in area configuration mode, then the interface adopts the priority parameter specified for the process.

If this command is not specified at any level, then the default priority is 1.

Command Modes

Interface configuration

Area configuration

Router configuration

Command History


Release	Modification
Release 5.0.0	This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

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 point-to-point networks).

This priority value is used when you configure the Open Shortest Path First (OSPF) protocol for nonbroadcast networks using the neighbor command for OSPF.

Task ID


Task ID	Operations
ospf	read, write

Examples

The following example shows that priority is set through the priority and neighbor commands for Routers A and B and that the neighbor priority value must reflect that of the neighbor router:


  RP/0/RP0/CPU0:router# configure
  RP/0/RP0/CPU0:router(config)# interface GigabitEthernet 0/1/0/1
  RP/0/RP0/CPU0:router(config-if)# ipv4 address 10.0.0.2 255.255.255.0
  RP/0/RP0/CPU0:router(config-if)# exit
  RP/0/RP0/CPU0:router(config)# router ospf 1
  RP/0/RP0/CPU0:router(config-ospf)# area 0
  RP/0/RP0/CPU0:router(config-ospf-ar)# interface GigabitEthernet 0/1/0/1
  RP/0/RP0/CPU0:router(config-ospf-ar-if)# network non-broadcast
  RP/0/RP0/CPU0:router(config-ospf-ar-if)# priority 4
  RP/0/RP0/CPU0:router(config-ospf-ar-if)# neighbor 10.0.0.1 priority 6


  RP/0/RP0/CPU0:router# configure
  RP/0/RP0/CPU0:router(config)# interface GigabitEthernet POS 0/2/0/1
  RP/0/RP0/CPU0:router(config-if)# ipv4 address 10.0.0.1 255.255.255.0
  RP/0/RP0/CPU0:router(config-if)# exit
  RP/0/RP0/CPU0:router(config)# router ospf 1
  RP/0/RP0/CPU0:router(config-ospf)# area 0
  RP/0/RP0/CPU0:router(config-ospf-ar)# interface GigabitEthernet 0/2/0/1
  RP/0/RP0

Results

Chapter: OSPF Commands

OSPF Commands

address-family (OSPF)

Syntax Description

Command Default

Command Modes

Command History

Usage Guidelines

Task ID

Examples

adjacency stagger

Syntax Description

Command Default

Command Modes

Command History

Usage Guidelines

Task ID

Examples

area (OSPF)

Syntax Description

Command Default

Command Modes

Command History

Usage Guidelines

Task ID

Examples

authentication (OSPF)

Syntax Description

Command Default

Command Modes

Command History

Usage Guidelines

Task ID

Examples

Related Commands

authentication-key (OSPF)

Syntax Description

Command Default

Command Modes

Command History

Usage Guidelines

Task ID

Examples

Related Commands

auto-cost (OSPF)

Syntax Description

Command Default

Command Modes

Command History

Usage Guidelines

Task ID

Examples

Related Commands

capability opaque disable

Command Default

Command Modes

Command History

Usage Guidelines

Task ID

Examples

clear ospf process

Syntax Description

Command Default

Command Modes

Command History

Usage Guidelines

Task ID

Examples

Related Commands

clear ospf redistribution

Syntax Description

Command Default

Command Modes

Command History

Usage Guidelines

Task ID

Examples

clear ospf routes