Cisco IOS IP Routing: Protocol-Independent Command Reference

IP Routing Protocol-Independent Commands

accept-lifetime

To set the time period during which the authentication key on a key chain is received as valid, use the accept-lifetime command in key chain key configuration mode. To revert to the default value, use the no form of this command.

accept-lifetime start-time {infinite | end-time | duration seconds}

no accept-lifetime [start-time {infinite | end-time | duration seconds}]

Syntax Description

Command Default

Forever (the starting time is January 1, 1993, and the ending time is infinite)

Command Modes

Key chain key configuration

Command History

Usage Guidelines

Only DRP Agent, Enhanced Interior Gateway Routing Protocol (EIGRP), and Routing Information Protocol (RIP) Version 2 use key chains.

Specify a start-time value and one of the following values: infinite, end-time, or duration seconds.

We recommend running Network Time Protocol (NTP) or some other time synchronization method if you assign a lifetime to a key.

If the last key expires, authentication will continue and an error message will be generated. To disable authentication, you must manually delete the last valid key.

Examples

The following example configures a key chain called keychain1. The key named string1 will be accepted from 1:30 p.m. to 3:30 p.m. and be sent from 2:00 p.m. to 3:00 p.m. The key named string2 will be accepted from 2:30 p.m. to 4:30 p.m. and be sent from 3:00 p.m. to 4:00 p.m. The overlap allows for migration of keys or discrepancies in the set time of the router. There is a 30-minute leeway on each side to handle time differences.

interface ethernet 0

 ip rip authentication key-chain keychain1

 ip rip authentication mode md5

!

router rip

 network 172.19.0.0

 version 2

!

key chain keychain1

 key 1

 key-string string1

 accept-lifetime 13:30:00 Jan 25 1996 duration 7200

 send-lifetime 14:00:00 Jan 25 1996 duration 3600

 key 2

 key-string string2

 accept-lifetime 14:30:00 Jan 25 1996 duration 7200

 send-lifetime 15:00:00 Jan 25 1996 duration 3600

Related Commands

bfd

To set the baseline Bidirectional Forwarding Detection (BFD) session parameters on an interface, use the bfd command in interface configuration mode. To remove the baseline BFD session parameters, use the no form of this command.

bfd interval milliseconds min_rx milliseconds multiplier multiplier-value

no bfd interval milliseconds min_rx milliseconds multiplier multiplier-value

Syntax Description

Command Default

No baseline BFD session parameters are set.

Command Modes

Interface configuration (config-if)

Command History

Usage Guidelines

The bfd command can be configured on the following interfaces:

•ATM

•Dot1Q VLAN subinterfaces (with an IP address on the Dot1Q subinterface)

•Ethernet

•Frame Relay

•IMA

•PoS

•Serial

Other interface types are not supported by BFD.

Note The bfd interval command is not supported on ATM and IMA interfaces in Cisco IOS Release 15.0(1)M and later releases.

Examples

The following example shows the BFD session parameters set for Fast Ethernet interface 3/0:

Router> enable

Router# configure terminal

Router(config)# interface fastethernet 3/0

Router(config-if)# bfd interval 50 min_rx 50 multiplier 3

Router(config-if)# end

Related Commands

bfd all-interfaces

To enable Bidirectional Forwarding Detection (BFD) for all interfaces participating in the routing process, use the bfd all-interfaces command in router configuration or address-family interface configuration mode. To disable BFD for all neighbors on a single interface, use the no form of this command.

bfd all-interfaces

no bfd all-interfaces

Syntax Description

This command has no arguments or keywords.

Command Default

BFD is disabled on the interfaces participating in the routing process.

Command Modes

Router configuration (config-router) and address-family interface configuration (config-router-af)

Command History

Usage Guidelines

There are two methods to configure routing protocols to use BFD for failure detection. To enable BFD for all interfaces, enter the bfd all-interfaces command in router configuration mode. In Cisco IOS Release 12.4(24)T, Cisco IOS 12.2(33)SRA and earlier releases, the bfd all-interfaces command works in router configuration mode and address-family interface mode.

In Cisco IOS Release 15.0(1)M and later releases, the bfd all-interfaces command in named router configuration mode is replaced by the bfd command in address-family interface configuration mode. Use the bfd command in address-family interface configuration mode to achieve the same functionality as that of the bfd all interfaces command in router configuration mode.

Examples

The following example shows how to enable BFD for all Enhanced Interior Gateway Routing Protocol (EIGRP) neighbors:

Router> enable

Router# configure terminal

Router(config)# router eigrp 123

Router(config-router)# bfd all-interfaces

Router(config-router)# end

The following example shows how to enable BFD for all Intermediate System-to-Intermediate System (IS-IS) neighbors:

Router> enable

Router# configure terminal

Router(config)# router isis tag1

Router(config-router)# bfd all-interfaces

Router(config-router)# end

The following example shows how to enable BFD for all Open Shortest Path First (OSPF) neighbors:

Router> enable

Router# configure terminal

Router(config)# router ospf 123

Router(config-router)# bfd all-interfaces

Router(config-router)# end

The following example shows how to enable BFD for all EIGRP neighbors, using the bfd command in address-family interface configuration mode:

Router> enable

Router# configure terminal

Router(config)# router eigrp my_eigrp

Router(config-router)# address-family ipv4 autonomous-system 100 

Router(config-router-af)# af-interface FastEthernet 0/0

Router(config-router-af-interface)# bfd

The following example shows how to enable BFD for all Routing Information Protocol (RIP) neighbors:

Router> enable

Router# configure terminal

Router(config)# router rip

Router(config-router)# bfd all-interfaces

Router(config-router)# end

Related Commands

bfd echo

To enable Bidirectional Forwarding Detection (BFD) echo mode, use the bfd echo command in interface configuration mode. To disable BFD echo mode, use the no form of this command.

bfd echo

no bfd echo

Syntax Description

This command has no arguments or keywords.

Command Default

BFD echo mode is enabled by default.

Command Modes

Interface configuration (config-if)

Command History

Usage Guidelines

Echo mode is enabled by default. Entering the no bfd echo command without any keywords turns off the sending of echo packets and signifies that the router is unwilling to forward echo packets received from BFD neighbor routers.

When echo mode is enabled, the desired minimum echo transmit interval and required minimum transmit interval values are taken from the bfd interval milliseconds min_rx milliseconds parameters, respectively.

Note If the no ip route-cache same-interface command is configured, the bfd echo accept command will not be accepted.

Note Before using BFD echo mode, you must disable the sending of Internet Control Message Protocol (ICMP) redirect messages by entering the no ip redirects command, in order to avoid high CPU utilization.

The bfd echo command is not supported on ATM and IMA interfaces Cisco IOS Release 15.0(1)M and later releases.

Echo Mode Without Asymmetry

Echo mode is described as without asymmetry when it is running on both sides (both BFD neighbors are running echo mode).

Examples

The following example configures echo mode between BFD neighbors:

Router> enable

Router# configure terminal

Router(config)# interface Ethernet 0/1

Router(config-if)# bfd echo

The following output from the show bfd neighbors details command shows that the BFD session neighbor is up and using BFD echo mode. The relevant command output is shown in bold in the output.

Router# show bfd neighbors details

OurAddr       NeighAddr      LD/RD  RH/RS    Holdown(mult)State    Int

172.16.1.2    172.16.1.1     1/6    Up       0    (3 )    Up       Fa0/1       

Session state is UP and using echo function with 50 ms interval.

Local Diag: 0, Demand mode: 0, Poll bit: 0

MinTxInt: 1000000, MinRxInt: 1000000, Multiplier: 3

Received MinRxInt: 1000000, Received Multiplier: 3

Holdown (hits): 3000(0), Hello (hits): 1000(337)

Rx Count: 341, Rx Interval (ms) min/max/avg: 1/1008/882 last: 364 ms ago

Tx Count: 339, Tx Interval (ms) min/max/avg: 1/1016/886 last: 632 ms ago

Registered protocols: EIGRP

Uptime: 00:05:00

Last packet: Version: 1            - Diagnostic: 0

             State bit: Up         - Demand bit: 0

             Poll bit: 0           - Final bit: 0

             Multiplier: 3         - Length: 24

             My Discr.: 6          - Your Discr.: 1

             Min tx interval: 1000000    - Min rx interval: 1000000

             Min Echo interval: 50000

Related Commands

bfd interface

To enable Bidirectional Forwarding Detection (BFD) on a per-interface basis for a BFD peer, use the bfd interface command in router configuration mode. To disable BFD on a per-interface basis, use the no form of this command.

bfd interface type number

no bfd interface type number

Syntax Description

Command Default

BFD is not enabled on the interface.

Command Modes

Router configuration

Command History

Usage Guidelines

There are two methods to configure routing protocols to use BFD for failure detection. To enable BFD for all neighbors of a routing protocol, enter the bfd all-interfaces command in router configuration mode. If you do not want to enable BFD on all interfaces, enter the bfd interface command in router configuration mode.

Examples

The following example shows BFD enabled for the Enhanced Interior Gateway Routing Protocol (EIGRP) neighbor Fast Ethernet interface 3/0:

Router> enable

Router# configure terminal

Router(config)# router eigrp 123

Router(config-router)# bfd interface fastethernet 3/0

Router(config-if)# end

Related Commands

bfd slow-timers

To configure the Bidirectional Forwarding Detection (BFD) slow timers value, use the bfd slow-timers command in global configuration mode. This command does not have a no form.

bfd slow-timers [milliseconds]

Syntax Description

Command Default

The BFD slow timer value is 1000 milliseconds.

Command Modes

Global configuration (config)

Command History

Examples

The following example shows how to configure the BFD slow timers value to 14,000 milliseconds:

Router(config)# bfd slow-timers 14000

The following output from the show bfd neighbors details command shows that the BFD slow timers value of 14,000 milliseconds has been implemented. The values for the MinTxInt and MinRxInt will correspond to the configured value for the BFD slow timers. The relevant command output is shown in bold.

Router# show bfd neighbors details

OurAddr       NeighAddr     LD/RD  RH/RS   Holdown(mult)  State     Int

172.16.10.1   172.16.10.2   1/1    Up      0    (3 )      Up        Et2/0

Session state is UP and using echo function with 50 ms interval.

Local Diag: 0, Demand mode: 0, Poll bit: 0

MinTxInt: 14000, MinRxInt: 14000, Multiplier: 3

Received MinRxInt: 10000, Received Multiplier: 3

Holdown (hits): 3600(0), Hello (hits): 1200(418)

Rx Count: 422, Rx Interval (ms) min/max/avg: 1/1480/1087 last: 112 ms ago

Tx Count: 420, Tx Interval (ms) min/max/avg: 1/2088/1090 last: 872 ms ago

Registered protocols: OSPF

Uptime: 00:07:37

Last packet: Version: 1            - Diagnostic: 0

             State bit: Up         - Demand bit: 0

             Poll bit: 0           - Final bit: 0

             Multiplier: 3         - Length: 24

             My Discr.: 1          - Your Discr.: 1

             Min tx interval: 14000 - Min rx interval: 14000

             Min Echo interval: 4000

Related Commands

bfd-template

To create a Bidirectional Forwarding Detection (BFD) template and to enter BFD configuration mode, use the bfd-template command in global configuration mode. To disable a BFD template, use the no form of this command.

bfd-template single-hop template-name

no bfd-template single-hop template-name

Syntax Description

Command Default

The BFD template does not exist.

Command Modes

Global configuration (config)

Command History

Usage Guidelines

The bfd-template command allows you to create a BFD template and enter BFD configuration mode. The template can be used to specify a set of BFD interval values. BFD interval values specified as part of the BFD template are not specific to a single interface.

Examples

The following example shows how to create a BFD template and specify BFD interval values:

Router(config)# bfd-template single-hop node1 

Router(bfd-config)# interval min-tx 100 min-rx 100 multiplier 3

Related Commands

dampening

To configure a router to automatically dampen a flapping interface, use the dampening command in interface configuration mode. To disable automatic route dampening, use the no form of this command.

dampening [half-life-period reuse-threshold] [suppress-threshold max-suppress-time [restart-penalty]]

no dampening

Syntax Description

Defaults

This command is disabled by default. To manually configure the timer for the restart-penalty argument, the value for all arguments must be manually entered.

Command Modes

Interface configuration

Command History

Usage Guidelines

The IP Event Dampening feature will function on a subinterface but cannot be configured on only the subinterface. Only the primary interface can be configured with this feature. Primary interface configuration is applied to all subinterfaces by default.

When an interface is dampened, the interface is dampened to both IP and Connectionless Network Services (CLNS) routing equally. The interface is dampened to both IP and CLNS because integrated routing protocols such as Intermediate System-to-Intermediate System (IS-IS), IP, and CLNS routing protocols are closely interconnected, so it is impossible to apply dampening separately.

Copying a dampening configuration from virtual templates to virtual access interfaces is not supported because dampening has limited usefulness to existing applications using virtual templates. Virtual access interfaces are released when an interface flaps, and new connections and virtual access interfaces are acquired when the interface comes up and is made available to the network. Because dampening states are attached to the interface, the dampening states would not survive an interface flap.

If the dampening command is applied to an interface that already has dampening configured, all dampening states are reset and the accumulated penalty will be set to 0. If the interface has been dampened, the accumulated penalty will fall into the reuse threshold range, and the dampened interface will be made available to the network. The flap counts, however, are retained.

Examples

The following example sets the half life to 30 seconds, the reuse threshold to 1500, the suppress threshold to 10000, and the maximum suppress time to 120 seconds:

interface Ethernet 0/0

 dampening 30 1500 10000 120

The following example configures the router to apply a penalty of 500 on Ethernet interface 0/0 when the interface comes up for the first time after the router is reloaded:

interface Ethernet 0/0

 dampening 5 500 1000 20 500 

Related Commands

distance (IP)

To define an administrative distance for routes that are inserted into the routing table, use the distance command in router configuration mode. To return the administrative distance to its default distance definition, use the no form of this command.

distance distance ip-address wildcard-mask [ip-standard-acl | ip-extended-acl | access-list-name]

no distance distance ip-address wildcard-mask [ip-standard-acl | ip-extended-acl | access-list-name]

Syntax Description

Command Default

For information on default administrative distances, see the "Usage Guidelines" section.

Command Modes

Router configuration (config-router)

Command History

Usage Guidelines

Table 1 lists default administrative distances.

An administrative distance is a rating of the trustworthiness of a routing information source, such as an individual router or a group of routers. Numerically, an administrative distance is an integer from 0 to 255. In general, the higher the value, the lower the trust rating. An administrative distance of 255 means the routing information source cannot be trusted at all and should be ignored.

When the optional access list name is used with this command, it is applied when a network is being inserted into the routing table. This behavior allows filtering of networks according to the IP address of the router that supplies the routing information. This option could be used, for example, to filter possibly incorrect routing information from routers that are 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.

For BGP, the distance command sets the administrative distance of the External BGP (eBGP) route.

The show ip protocols privileged EXEC command displays the default administrative distance for the active routing processes.

Always set the administrative distance from the least to the most specific network.

Note The weight of a route can no longer be set with the distance command. To set the weight for a route,
use a route map.

Examples

In the following example, the router eigrp global configuration command sets up EIGRP routing in autonomous system number 109. The network router configuration commands specify EIGRP routing on networks 192.168.7.0 and 172.16.0.0. The first distance command sets the administrative distance to 90 for all routers on the Class C network 192.168.7.0. The second distance command sets the administrative distance to 120 for the router with the address 172.16.1.3.

Router> enable

Router# configure terminal

Router(config)# router eigrp 109

Router(config-router)# network 192.168.7.0

Router(config-router)# network 172.16.0.0

Router(config-router)# distance 90 192.168.7.0 0.0.0.255

Router(config-router)# distance 120 172.16.1.3 0.0.0.255

Router(config-router)# end

In the following example, the set distance is from the least to the most specific network:

Router> enable

Router# configure terminal

Router(config)# router eigrp 109

Router(config-router)# distance 22 10.0.0.0 0.0.0.255

Router(config-router)# distance 33 10.11.0.0 0.0.0.255

Router(config-router)# distance 44 10.11.12.0 0.0.0.255

Router(config-router)# end

Note In this example, adding distance 255 to the end of the list would override the distance values for all networks within the range specified in the example. The result would be that the distance values are set to 255.

Entering the show ip protocols command displays the default administrative distance for the active routing processes, as well as the user-configured administrative distances:

Router# show ip protocols

.

.

.

Routing Protocol is "isis tag1"

  Invalid after 0 seconds, hold down 0, flushed after 0

  Outgoing update filter list for all interfaces is not set

  Incoming update filter list for all interfaces is not set

  Redistributing: isis

  Address Summarization:

    None

  Maximum path: 4

  Routing for Networks:

  Routing Information Sources:

    Gateway         Distance      Last Update

  Distance: (default is 115)

    Address         Wild mask       Distance  List

    10.11.0.0             0.0.0.255       45

    10.0.0.0              0.0.0.255       22

    Address         Wild mask       Distance  List

    10.11.0.0             0.0.0.255       33

    10.11.12.0            0.0.0.255       44

Related Commands

distribute-list in (IP)

To filter networks received in updates, use the distribute-list in command in the appropriate configuration mode. To change or cancel the filter, use the no form of this command.

distribute-list [[access-list-number | name] | [route-map map-tag]] in [interface-type | interface-number]

no distribute-list [[access-list-number | name] | [route-map map-tag]] in [interface-type | interface-number]

Syntax Description

Defaults

This command is disabled by default.

Command Modes

Address family configuration (config-af)
Router address family topology configuration (config-router-af-topology)
Router configuration (config-router)

Command History

Usage Guidelines

This command must specify either an access list or a map-tag name of a route map. The route map is supported for OSPF and EIGRP filtering.

The interface-type and interface-number arguments cannot be used in address family configuration mode.

OSPF routes cannot be filtered from entering the OSPF database. If you use this command for OSPF, it only filters routes from the routing table; it does not prevent link-state packets from being propagated.

If a route map is specified, the route map can be based on the following match options:

•match interface

•match ip address

•match ip next-hop

•match ip route-source

•match metric

•match route-type

•match tag

Configure the route map before specifying it in the distribute-list in command.

Release 12.2(33)SRB

If you plan to configure the Multi-Topology Routing (MTR) feature, you need to enter the distribute-list in command in router address family topology configuration mode in order for this OSPF router configuration command to become topology-aware.

Examples

In the following example, EIGRP process 1 is configured to accept two networks—network 0.0.0.0 and network 10.108.0.0:

access-list 1 permit 0.0.0.0

access-list 1 permit 10.108.0.0

access-list 1 deny 0.0.0.0 255.255.255.255

router eigrp 1 

 network 10.108.0.0

 distribute-list 1 in

In the following example, OSPF external LSAs have a tag. The value of the tag is examined before the prefix is installed in the routing table. All OSPF external prefixes that have the tag value of 777 are filtered (prevented from being installed in the routing table). The permit statement with sequence number 20 has no match conditions, and there are no other route-map statements after sequence number 20, so all other conditions are permitted.

route-map tag-filter deny 10

 match tag 777

route-map tag-filter permit 20

!

router ospf 1

 router-id 10.0.0.2

 log-adjacency-changes

 network 172.16.2.1 0.0.0.255 area 0

 distribute-list route-map tag-filter in

Related Commands

distribute-list out (IP)

To suppress networks from being advertised in updates, use the distribute-list out command in the appropriate configuration mode. To cancel this function, use the no form of this command.

distribute-list {access-list-number | access-list-name} out [interface-name | routing-process | as-number]

no distribute-list {access-list-number | access-list-name} out [interface-name | routing-process | as-number]

Syntax Description

Defaults

This command is disabled by default. Networks are advertised in updates.

Command Modes

Address family configuration (config-af)
Router address family topology configuration (config-router-af-topology)
Router configuration (config-router)

Command History

Usage Guidelines

When networks are redistributed, a routing process name can be specified as an optional trailing argument to the distribute-list command. Specifying this option causes the access list to be applied to only those routes derived from the specified routing process. After the process-specific access list is applied, any access list specified by a distribute-list command without a process name argument will be applied. Addresses not specified in the distribute-list command will not be advertised in outgoing routing updates.

The interface-name argument cannot be used in address family configuration mode.

Note To filter networks received in updates, use the distribute-list in command.

Release 12.2(33)SRB

If you plan to configure the Multi-Topology Routing (MTR) feature, you need to enter the distribute-list out command in router address family topology configuration mode in order for this OSPF router configuration command to become topology-aware.

Examples

The following example would cause only one network to be advertised by a RIP routing process, network 10.108.0.0:

access-list 1 permit 10.108.0.0

access-list 1 deny 0.0.0.0 255.255.255.255

router rip

 network 10.108.0.0

 distribute-list 1 out

The following example applies access list 1 to outgoing routing updates. Only network 10.10.101.0 will be advertised in outgoing EIGRP routing updates.

router eigrp 100

 distribute-list 1 out

access-list 1 permit 10.10.101.0 0.0.0.255

Related Commands

interval (BFD)

To configure the transmit and receive intervals between BFD packets, and to specify the number of consecutive BFD control packets that must be missed before BFD declares that a peer is unavailable, use the interval command in BFD configuration mode. To disable interval values use the no form of this command.

interval {both milliseconds | min-tx milliseconds min-rx milliseconds} [multiplier multiplier-value]

no interval

Syntax Description

Command Default

No session parameters are set.

Command Modes

BFD configuration (config-bfd)

Command History

Usage Guidelines

The interval command allows you to configure the session parameters for a BFD template.

Examples

The following example shows how to configure interval settings for the node1 BFD template:

Router(config)# bfd-template single-hop node1 

Router(bfd-config)# interval min-tx 120 min-rx 100 multiplier 3

Related Commands

ip default-network

To select a network as a candidate route for computing the gateway of last resort, use the ip default-network command in global configuration mode. To remove a route, use the no form of this command.

ip default-network network-number

no ip default-network network-number

Syntax Description

Command Default

If the router has a directly connected interface onto the specified network, the dynamic routing protocols running on that router will generate (or source) a default route. For Router Information Protocol (RIP), this is flagged as the pseudonetwork 0.0.0.0.

Command Modes

Global configuration

Command History

Usage Guidelines

The Cisco IOS software uses both administrative distance and metric information to determine the default route. Multiple ip default-network commands can be given. All candidate default routes, both static (that is, flagged by the ip default-network command) and dynamic, appear in the routing table preceded by an asterisk.

If the IP routing table indicates that the specified network number is subnetted and a nonzero subnet number is specified, then the system will automatically configure a static summary route. This static summary route is configured instead of a default network. The effect of the static summary route is to cause traffic destined for subnets that are not explicitly listed in the IP routing table to be routed using the specified subnet.

Examples

The following example defines a static route to network 10.0.0.0 as the static default route:

ip route 10.0.0.0 255.0.0.0 10.108.3.4

ip default-network 10.0.0.0

If the following command was issued on a router not connected to network 10.140.0.0, the software might choose the path to that network as a default route when the network appeared in the routing table:

ip default-network 10.140.0.0

Related Commands

ip gdp

To configure the router discovery mechanism, use the ip gdp command in global configuration mode. To disable the configuration, use the no form of this command.

ip gdp {eigrp | irdp [multicast] | rip}

no ip gdp {eigrp | irdp [multicast] | rip}

Syntax Description

Command Default

The router discovery mechanism is not configured.

Command Modes

Global configuration (config)

Command History

Usage Guidelines

You must disable IP routing to configure the ip gdp command.

Examples

The following example shows how to configure the RIP router discovery mechanism:

Router# configure terminal

Router(config)# ip gdp rip

Related Commands

ip local policy route-map

To identify a route map to use for local policy routing, use the ip local policy route-map command in global configuration mode. To disable local policy routing, use the no form of this command.

ip local policy route-map map-tag

no ip local policy route-map map-tag

Syntax Description

Defaults

Packets that are generated by the router are not policy routed.

Command Modes

Global configuration

Command History

Usage Guidelines

Packets that are generated by the router are not normally policy routed. However, you can use this command to policy route such packets. You might enable local policy routing if you want packets originated at the router to take a route other than the obvious shortest path.

The ip local policy route-map command identifies a route map to use for local policy routing. Each route-map command has a list of match and set commands associated with it. The match commands specify the match criteria—the conditions under which packets should be policy routed. The set commands specify the set actions—the particular policy routing actions to perform if the criteria enforced by the match commands are met. The no ip local policy route-map command deletes the reference to the route map and disables local policy routing.

Examples

The following example sends packets with a destination IP address matching that allowed by extended access list 131 to the router at IP address 172.30.3.20:

ip local policy route-map xyz

!

route-map xyz

 match ip address 131

 set ip next-hop 172.30.3.20

Related Commands

ip policy route-map

To identify a route map to use for policy routing on an interface, use the ip policy route-map command in interface configuration mode. To disable policy routing on the interface, use the no form of this command.

ip policy route-map map-tag

no ip policy route-map

Syntax Description

Defaults

No policy routing occurs on the interface.

Command Modes

Interface configuration

Command History

Usage Guidelines

You might enable policy routing if you want your packets to take a route other than the obvious shortest path.

The ip policy route-map command identifies a route map to use for policy routing. Each route-map command has a list of match and set commands associated with it. The match commands specify the match criteria—the conditions under which policy routing is allowed for the interface, based on the destination IP address of the packet. The set commands specify the set actions—the particular policy routing actions to perform if the criteria enforced by the match commands are met. The no ip policy route-map command deletes the pointer to the route map.

Policy routing can be performed on any match criteria that can be defined in an extended IP access list when using the match ip address command and referencing an extended IP access list.

Examples

The following example sends packets with the destination IP address of 172.21.16.18 to a router at IP address 172.30.3.20:

interface serial 0

 ip policy route-map policy_marketing

!

route-map policy_marketing

 match ip address 172.21.16.18

 set ip next-hop 172.30.3.20

Related Commands

ip route

To establish static routes, use the ip route command in global configuration mode. To remove static routes, use the no form of this command.

ip route [vrf vrf-name] prefix mask {ip-address | interface-type interface-number [ip-address]} [dhcp] [distance] [name next-hop-name] [permanent | track number] [tag tag]

no ip route [vrf vrf-name] prefix mask {ip-address | interface-type interface-number [ip-address]} [dhcp] [distance] [name next-hop-name] [permanent | track number] [tag tag]

Syntax Description

Command Default

No static routes are established.

Command Modes

Global configuration (config)

Command History

Usage Guidelines

The establishment of a static route is appropriate when the Cisco IOS software cannot dynamically build a route to the destination.

When you specify a DHCP server to assign a static route, the interface type and number and administrative distance may be configured also.

If you specify an administrative distance, you are flagging a static route that can be overridden by dynamic information. For example, routes derived with Enhanced Interior Gateway Routing Protocol (EIGRP) have a default administrative distance of 90. To have a static route that would be overridden by an EIGRP dynamic route, specify an administrative distance greater than 100. Static routes have a default administrative distance of 100.

Static routes that point to an interface on a connected router will be advertised by way of Routing Information Protocol (RIP) and EIGRP regardless of whether redistribute static commands are specified for those routing protocols. This situation occurs because static routes that point to an interface are considered in the routing table to be connected and hence lose their static nature. Also, the target of the static route should be included in the network (DHCP) command. If this condition is not met, no dynamic routing protocol will advertise the route unless a redistribute static command is specified for these protocols. With the following configuration:

rtr1 (serial 172.16.188.1/30)--------------> rtr2(Fast Ethernet 172.31.1.1/30) ------>

router [rip | eigrp]

 network 172.16.188.0

 network 172.31.0.0 

•RIP and EIGRP redistribute the route if the route is pointing to the Fast Ethernet interface:

ip route 172.16.188.252 255.255.255.252 FastEthernet 0/0 

RIP and EIGRP do not redistribute the route with the following ip route command because of the split horizon algorithm:

ip route 172.16.188.252 255.255.255.252 serial 2/1 

•EIGRP redistributes the route with both of the following commands:

ip route 172.16.188.252 255.255.255.252 FastEthernet 0/0

ip route 172.16.188.252 255.255.255.252 serial 2/1 

With the Open Shortest Path First (OSPF) protocol, static routes that point to an interface are not advertised unless a redistribute static command is specified.

Adding a static route to an Ethernet or other broadcast interface (for example, ip route 0.0.0.0 0.0.0.0 Ethernet 1/2) will cause the route to be inserted into the routing table only when the interface is up. This configuration is not generally recommended. When the next hop of a static route points to an interface, the router considers each of the hosts within the range of the route to be directly connected through that interface, and therefore it will send Address Resolution Protocol (ARP) requests to any destination addresses that route through the static route.

A logical outgoing interface, for example, a tunnel, needs to be configured for a static route. If this outgoing interface is deleted from the configuration, the static route is removed from the configuration and hence does not show up in the routing table. To have the static route inserted into the routing table again, configure the outgoing interface once again and add the static route to this interface.

The practical implication of configuring the ip route 0.0.0.0 0.0.0.0 ethernet 1/2 command is that the router will consider all of the destinations that the router does not know how to reach through some other route as directly connected to Ethernet interface 1/2. So the router will send an ARP request for each host for which it receives packets on this network segment. This configuration can cause high processor utilization and a large ARP cache (along with memory allocation failures). Configuring a default route or other static route that directs the router to forward packets for a large range of destinations to a connected broadcast network segment can cause your router to reload.

Specifying a numerical next hop that is on a directly connected interface will prevent the router from using proxy ARP. However, if the interface with the next hop goes down and the numerical next hop can be reached through a recursive route, you may specify both the next hop and interface (for example, ip route 0.0.0.0 0.0.0.0 ethernet 1/2 10.1.2.3) with a static route to prevent routes from passing through an unintended interface.

Note Configuring a default route that points to an interface, such as ip route 0.0.0.0 0.0.0.0 ethernet 1/2, displays a warning message. This command causes the router to consider all the destinations that the router cannot reach through an alternate route, as directly connected to Ethernet interface 1/2. Hence, the router sends an ARP request for each host for which it receives packets on this network segment. This configuration can cause high processor utilization and a large ARP cache (along with memory allocation failures). Configuring a default route or other static route that directs the router to forward packets for a large range of destinations to a connected broadcast network segment can cause the router to reload.

The name next-hop-name keyword and argument combination allows you to associate static routes with names in your running configuration. If you have several static routes, you can specify names that describe the purpose of each static route in order to more easily identify each one.

The track number keyword and argument combination specifies that the static route will be installed only if the state of the configured track object is up.

Recursive Static Routing

In a recursive static route, only the next hop is specified. The output interface is derived from the next hop.

For the following recursive static route example, all destinations with the IP address prefix address prefix 192.168.1.1/32 are reachable via the host with address 10.0.0.2:

ip route 192.168.1.1 255.255.255.255 10.0.0.2

A recursive static route is valid (that is, it is a candidate for insertion in the IPv4 routing table) only when the specified next hop resolves, either directly or indirectly, to a valid IPv4 output interface, provided the route does not self-recurse, and the recursion depth does not exceed the maximum IPv4 forwarding recursion depth.

The following example defines a valid recursive IPv4 static route:

interface serial 2/0

 ip address 10.0.0.1 255.255.255.252

 exit

ip route 192.168.1.1 255.255.255.255 10.0.0.2

The following example defines an invalid recursive IPv4 static route. This static route will not be inserted into the IPv4 routing table because it is self-recursive. The next hop of the static route, 192.168.1.0/30, resolves via the first static route 192.168.1.0/24, which is itself a recursive route (that is, it only specifies a next hop). The next hop of the first route, 192.168.1.0/24, resolves via the directly connected route via the serial interface 2/0. Therefore, the first static route would be used to resolve its own next hop.

interface serial 2/0

 ip address 10.0.0.1 255.255.255.252

 exit

ip route 192.168.1.0 255.255.255.0 10.0.0.2

ip route 192.168.1.0 255.255.255.252 192.168.1.100

It is not normally useful to manually configure a self-recursive static route, although it is not prohibited. However, a recursive static route that has been inserted in the IPv4 routing table may become self-recursive as a result of some transient change in the network learned through a dynamic routing protocol. If this situation occurs, the fact that the static route has become self-recursive will be detected and the static route will be removed from the IPv4 routing table, although not from the configuration. A subsequent network change may cause the static route to no longer be self-recursive, in which case it will be re-inserted in the IPv4 routing table.

Note IPv4 recursive static routes are checked at one-minute intervals. Therefore, a recursive static route may take up to a minute to be inserted into the routing table once its next hop becomes valid. Likewise, it may take a minute or so for the route to disappear from the table if its next hop becomes invalid.

Examples

The following example shows how to choose an administrative distance of 110. In this case, packets for network 10.0.0.0 will be routed to a router at 172.31.3.4 if dynamic information with an administrative distance less than 110 is not available.

ip route 10.0.0.0 255.0.0.0 172.31.3.4 110

Note Specifying the next hop without specifying an interface when configuring a static route can cause traffic to pass through an unintended interface if the default interface goes down.

The following example shows how to route packets for network 172.31.0.0 to a router at 172.31.6.6:

ip route 172.31.0.0 255.255.0.0 172.31.6.6 

The following example shows how to route packets for network 192.168.1.0 directly to the next hop at 10.1.2.3. If the interface goes down, this route is removed from the routing table and will not be restored unless the interface comes back up.

ip route 192.168.1.0 255.255.255.0 Ethernet 0 10.1.2.3 

The following example shows how to install the static route only if the state of track object 123 is up:

ip route 0.0.0.0 0.0.0.0 Ethernet 0/1 10.1.1.242 track 123

The following example shows that using the dhcp keyword in a configuration of Ethernet interfaces 1 and 2 enables the interfaces to obtain the next-hop router IP addresses dynamically from a DHCP server:

ip route 10.165.200.225 255.255.255.255 ethernet1 dhcp

ip route 10.165.200.226 255.255.255.255 ethernet2 dhcp 20

The following example shows that using the name next-hop-name keyword and argument combination for each static route in the configuration helps you remember the purpose for each static route.

ip route 172.0.0.0 255.0.0.0 10.0.0.1 name Seattle2Detroit

The name for the static route will be displayed when the show running-configuration command is entered:

Router# show running-config | include ip route

ip route 172.0.0.0 255.0.0.0 10.0.0.1 name Seattle2Detroit

Related Commands

ip route profile

To enable IP routing table statistics collection, use the ip route profile command in global configuration mode. To disable collection of routing table statistics, use the no form of the command.

ip route profile

no ip route profile

Syntax Description

This command has no arguments or keywords.

Defaults

The time interval for each sample, or sampling interval, is a fixed value and is set at 5 seconds.

Command Modes

Global configuration

Command History

Usage Guidelines

The ip route profile command helps you to monitor routing table fluctuations that can occur as the result of route flapping, network failure, or network restoration.

This command identifies route flapping over brief time intervals. The time interval for each sample, or sampling interval, is a fixed value and is set at 5 seconds.

Two sets of statistics are collected. The per-interval statistics are collected over a sampling interval, while the routing table change statistics are the result of aggregating the per-interval statistics. The per-interval statistics are collected as a single set of counters, with one counter tracking one event. All counters are initialized at the beginning of each sampling interval; counters are incremented as corresponding events occur anywhere in the routing table.

At the end of a sampling interval, the per-interval statistics for that sampling interval are integrated with the routing table change statistics collected from the previous sampling intervals. The counters holding the per-interval statistics are reset and the process is repeated.

Routing table statistics are collected for the following events:

•Forward-Path Change. This statistic is the number of changes in the forwarding path, which is the accumulation of prefix-add, next-hop change, and pathcount change statistics.

•Prefix-Add. A new prefix was added to the routing table.

•Next-Hop Change. A prefix is not added or removed, but the next hop changes. This statistic is only seen with recursive routes that are installed in the routing table.

•Pathcount Change. The number of paths in the routing table has changed. This statistic is the result of an increase in the number of paths for an Interior Gateway Protocol (IGP) prefix in the routing table.

•Prefix Refresh. Standard routing table maintenance; the forwarding behavior is not changed.

Use the show ip route profile command to display the routing table change statistics.

Examples

The following example enables the collection of routing table statistics:

ip route profile

Related Commands

ip route static adjust-time

To change the time interval for IP static route adjustments during convergence, use the ip route static adjust-time command in global configuration mode. To reinstate the default adjustment time of 60 seconds, use the no form of this command.

ip route static adjust-time seconds

no ip route static adjust-time seconds

Syntax Description

Defaults

seconds: 60

Command Modes

Global configuration

Command History

Usage Guidelines

By default, static route adjustments are made every 60 seconds. To adjust the timer to any interval from 1 to 60 seconds, enter the ip route static adjust-time command.

The benefit of reducing the timer from the 60-second default value is to increase the convergence when static routes are used. However, reducing the interval can be CPU intensive if the value is set very low and a large number of static routes are configured.

Examples

In the following example, the adjustment time for static routes has been changed from the default 60 seconds to 30 seconds:

Router(config)# ip route static adjust-time 30

To remove the 30-second adjusted time interval and reinstate the default 60-second value, enter the no route ip static adjust-time command:

Router(config)# no ip route static adjust-time 30

Related Commands

ip route static bfd

To specify static route Bidirectional Forwarding Detection (BFD) neighbors, use the ip route static bfd command in global configuration mode. To remove a static route BFD neighbor, use the no form of this command.

ip route static bfd interface-type interface-number ip-address [group group-name [passive]]

no ip route static bfd {interface-type interface-number ip-address [group group-name [passive]] | group group-name}

Syntax Description

Command Default

No static BFD neighbors are specified.

Command Modes

Global configuration (config)

Command History

Usage Guidelines

Use the ip route static bfd command to specify static route BFD neighbors. All static routes that have the same interface and gateway specified in the configuration share the same BFD session for reachability notification.

All static routes that specify the same values for the interface-type, interface-number, and ip-address arguments will automatically use BFD to determine gateway reachability and take advantage of fast failure detection.

The interface-type, interface-number, and ip-address arguments are required because BFD supports only directly connected neighbors for the Cisco IOS 12.2(33)SRC and 15.1(2)S releases.

The group keyword assigns a BFD group. The static BFD configuration is added to the VPN routing and forwarding (VRF) instance with which the interface is associated. The passive keyword specifies the passive member of the group. Adding a static BFD in a group without the passive keyword makes it an active member of the group. A static route should be tracked by the active BFD configuration in order to trigger a BFD session for the group. To remove all the static BFD configurations (active and passive) of a specific group, use the no ip route static bfd command and specify the BFD group name.

BFD requires that BFD sessions are initiated on both endpoint routers. Therefore, this command must be configured on each endpoint router.

Examples

The following example shows how to configure the use of BFD for all static routes via a specified neighbor, group, and active member of the group:

Router# configure terminal

Router(config)# ip route static bfd GigabitEthernet 1/1 10.1.1.1 group group1

The following example shows how to configure the use of BFD for all static routes via a specified neighbor, group, and passive member of the group:

Router# configure terminal

Router(config)# ip route static bfd GigabitEthernet 1/2 10.2.2.2 group group1 passive

Related Commands

ip routing

To enable IP routing, use the ip routing command in global configuration mode. To disable IP routing, use the no form of this command.

ip routing

no ip routing

Syntax Description

This command has no arguments or keywords.

Defaults

IP routing is enabled.

Command Modes

Global configuration (config)

Command History

Usage Guidelines

To bridge IP, the no ip routing command must be configured to disable IP routing. However, you need not specify no ip routing in conjunction with concurrent routing and bridging to bridge IP.

The ip routing command is disabled on the Cisco VG200 voice over IP gateway.

Disabling IP routing is not allowed if you are running Cisco IOS Release 12.2SX on a Catalyst 6000 platform. The workaround is to not assign an IP address to the SVI.

Examples

The following example enables IP routing:

Router# configure terminal

Router(config)# ip routing

ip routing protocol purge interface

To purge the routes of the routing protocols when an interface goes down, use the ip routing protocol purge interface command in global configuration mode. To disable the purging of the routes, use the no form of this command.

ip routing protocol purge interface

no ip routing protocol purge interface

Syntax Description

This command has no arguments or keywords.

Command Default

Routing protocols purge the routes by default when an interface goes down.

Command Modes

Global configuration (config)

Command History

Usage Guidelines

The ip routing protocol purge interface command allows the Routing Information Base (RIB) to ignore interface events for protocols that can respond to interface failures, thus eliminating any unnecessary deletion by the RIB. This in turn results in a single modify event to the Cisco Express Forwarding plane.

If the no ip routing protocol purge interface command is executed and a link goes down, the RIB process is automatically triggered to delete all prefixes that have the next hop on this interface from the RIB. The protocols on all the routers are notified, and if there is a secondary path, the protocols will update the RIB with the new path. When the process works through a large routing table, the process can consume many CPU cycles and increase the convergence time.

Examples

The following example shows how to disable the purge interface function for a routing protocol:

Router# configure terminal

Enter configuration commands, one per line.  End with CNTL/Z.

Router(config)# no ip routing protocol purge interface

Router(config)# end

key

To identify an authentication key on a key chain, use the key command in key-chain configuration mode. To remove the key from the key chain, use the no form of this command.

key key-id

no key key-id

Syntax Description

Command Default

No key exists on the key chain.

Command Modes

Key-chain configuration

Command History

Usage Guidelines

Only DRP Agent, Enhanced Interior Gateway Routing Protocol (EIGRP), and Routing Information Protocol (RIP) Version 2 use key chains.

It is useful to have multiple keys on a key chain so that the software can sequence through the keys as they become invalid after time, based on the accept-lifetime and send-lifetime key chain key command settings.

Each key has its own key identifier, which is stored locally. The combination of the key identifier and the interface associated with the message uniquely identifies the authentication algorithm and Message Digest 5 (MD5) authentication key in use. Only one authentication packet is sent, regardless of the number of valid keys. The software starts looking at the lowest key identifier number and uses the first valid key.

If the last key expires, authentication will continue and an error message will be generated. To disable authentication, you must manually delete the last valid key.

To remove all keys, remove the key chain by using the no key chain command.

Examples

The following example configures a key chain named chain1. The key named key1 will be accepted from 1:30 p.m. to 3:30 p.m. and be sent from 2:00 p.m. to 3:00 p.m. The key named key2 will be accepted from 2:30 p.m. to 4:30 p.m. and be sent from 3:00 p.m. to 4:00 p.m. The overlap allows for migration of keys or a discrepancy in the set time of the router. There is a 30-minute leeway on each side to handle time differences.

interface ethernet 0

 ip rip authentication key-chain chain1

 ip rip authentication mode md5

!

router rip

 network 172.19.0.0

 version 2

!

key chain chain1

 key 1

 key-string key1

 accept-lifetime 13:30:00 Jan 25 1996 duration 7200

 send-lifetime 14:00:00 Jan 25 1996 duration 3600

 key 2

 key-string key2

 accept-lifetime 14:30:00 Jan 25 1996 duration 7200

 send-lifetime 15:00:00 Jan 25 1996 duration 3600

Related Commands

key chain

To enable authentication for routing protocols, identify a group of authentication keys by using the key chain command in global configuration mode. To remove the key chain, use the no form of this command.

key chain name-of-chain

no key chain name-of-chain

Syntax Description

Command Default

No key chain exists.

Command Modes

Global configuration

Command History

Usage Guidelines

Only DRP Agent, Enhanced Interior Gateway Routing Protocol (EIGRP), and Routing Information Protocol (RIP) Version 2 use key chains.

You must configure a key chain with keys to enable authentication.

Although you can identify multiple key chains, we recommend using one key chain per interface per routing protocol. Upon specifying the key chain command, you enter key-chain configuration mode.

Examples

The following example configures a key chain named chain1. The key named key1 will be accepted from 1:30 p.m. to 3:30 p.m. and be sent from 2:00 p.m. to 3:00 p.m. The key named key2 will be accepted from 2:30 p.m. to 4:30 p.m. and be sent from 3:00 p.m. to 4:00 p.m. The overlap allows for migration of keys or a discrepancy in the set time of the router. There is a 30-minute leeway on each side to handle time differences.

interface ethernet 0

 ip rip authentication key-chain chain1

 ip rip authentication mode md5

!

router rip

 network 172.19.0.0

 version 2

!

key chain chain1

 key 1

 key-string key1

 accept-lifetime 13:30:00 Jan 25 1996 duration 7200

 send-lifetime 14:00:00 Jan 25 1996 duration 3600

  key 2

  key-string key2

  accept-lifetime 14:30:00 Jan 25 1996 duration 7200

  send-lifetime 15:00:00 Jan 25 1996 duration 3600

Related Commands

key-string (authentication)

To specify the authentication string for a key, use the key-string command in key chain key configuration mode. To remove the authentication string, use the no form of this command.

key-string text

no key-string text

Syntax Description

Command Default

No key exists.

Command Modes

Key chain key configuration

Command History

Usage Guidelines

Only DRP Agent, Enhanced Interior Gateway Routing Protocol (EIGRP), and Routing Information Protocol (RIP) Version 2 use key chains. Each key can have only one key string.

If password encryption is configured (with the service password-encryption command), the software saves the key string as encrypted text. When you write to the terminal with the more system:running-config command, the software displays key-string 7 encrypted text.

Examples

The following example configures a key chain named chain1. The key named key1 will be accepted from 1:30 p.m. to 3:30 p.m. and be sent from 2:00 p.m. to 3:00 p.m. The key named key2 will be accepted from 2:30 p.m. to 4:30 p.m. and be sent from 3:00 p.m. to 4:00 p.m. The overlap allows for migration of keys or a discrepancy in the set time of the router. There is a 30-minute leeway on each side to handle time differences.

interface ethernet 0

 ip rip authentication key-chain chain1

 ip rip authentication mode md5

!

router rip

 network 172.19.0.0

 version 2

!

key chain chain1

 key 1

 key-string key1

 accept-lifetime 13:30:00 Jan 25 1996 duration 7200

 send-lifetime 14:00:00 Jan 25 1996 duration 3600

 key 2

 key-string key2

 accept-lifetime 14:30:00 Jan 25 1996 duration 7200

 send-lifetime 15:00:00 Jan 25 1996 duration 3600

Related Commands

match interface (IP)

To distribute any routes that have their next hop out one of the interfaces specified, use the match interface command in route-map configuration mode. To remove the match interface entry, use the no form of this command.

match interface interface-type interface-number [... interface-type interface-number]

no match interface interface-type interface-number [... interface-type interface-number]

Syntax Description

Defaults

No match interfaces are defined.

Command Modes

Route-map configuration

Command History

Usage Guidelines

An ellipsis (...) in the command syntax indicates that your command input can include multiple values for the interface-type interface-number arguments.

Use the route-map global configuration command, and the match and set route-map configuration commands, to define the conditions for redistributing routes from one routing protocol into another. Each route-map command has a list of match and set commands associated with it. The match commands specify the match criteria—the conditions under which redistribution is allowed for the current route-map command. The set commands specify the set actions—the particular redistribution actions to perform if the criteria enforced by the match commands are met. The no route-map command deletes the route map.

The match route-map configuration command has multiple formats. The match commands may be given in any order, and all match commands must "pass" to cause the route to be redistributed according to the set actions given with the set commands. The no forms of the match commands remove the specified match criteria.

A route map can have several parts. Any route that does not match at least one match clause relating to a route-map command will be ignored; that is, the route will not be advertised for outbound route maps and will not be accepted for inbound route maps. If you want to modify only some data, you must configure a second route map section with an explicit match specified.

Examples

In the following example, routes that have their next hop out Ethernet interface 0 will be distributed:

route-map name

 match interface ethernet 0

Related Commands

match ip address

To distribute any routes that have a destination network number address that is permitted by a standard access list, an extended access list, or a prefix list, or to perform policy routing on packets, use the match ip address command in route-map configuration mode. To remove the match ip address entry, use the no form of this command.

match ip address {access-list-number [access-list-number... | access-list-name...] | access-list-name [access-list-number...| access-list-name] | prefix-list prefix-list-name [prefix-list-name...]}

no match ip address {access-list-number [access-list-number... | access-list-name...] | access-list-name [access-list-number...| access-list-name] | prefix-list prefix-list-name [prefix-list-name...]}

Syntax Description

Defaults

No access list numbers or prefix lists are specified.

Command Modes

Route-map configuration

Command History

Usage Guidelines

An ellipsis (...) in the command syntax indicates that your command input can include multiple values for the access-list-number, access-list-name, or prefix-list-name arguments.

Like matches in the same route map subblock are filtered with "or" semantics. If any one match clause is matched in the entire route map subblock, this match is treated as a successful match. Dissimilar match clauses are filtered with "and" semantics. So dissimilar matches are filtered logically. If the first set of conditions is not met, the second match clause is filtered. This process continues until a match occurs or there are no more match clauses.

Use route maps to redistribute routes or to subject packets to policy routing. Both purposes are described in this section.

Redistribution

Use the route-map global configuration command, and the match and set route-map configuration commands, to define the conditions for redistributing routes from one routing protocol into another. Each route-map command has a list of match and set commands associated with it. The match commands specify the match criteria—the conditions under which redistribution is allowed for the current route-map command. The set commands specify the set actions—the particular redistribution actions to perform if the criteria enforced by the match commands are met. The no route-map command deletes the route map.

The match route-map configuration command has multiple formats. The match commands can be given in any order, and all match commands must "pass" to cause the route to be redistributed according to the set actions given with the set commands. The no forms of the match commands remove the specified match criteria.

When you are passing routes through a route map, a route map can have several sections that contain specific match clauses. Any route that does not match at least one match clause relating to a route-map command will be ignored; that is, the route will not be advertised for outbound route maps and will not be accepted for inbound route maps. If you want to modify only some data, you must configure a second route map section with an explicit match specified.

Policy Routing

Another purpose of route maps is to enable policy routing. The match ip address command allows you to policy route packets based on criteria that can be matched with an extended access list; for example, a protocol, protocol service, and source or destination IP address. To define the conditions for policy routing packets, use the ip policy route-map interface configuration command, in addition to the route-map global configuration command, and the match and set route-map configuration commands. Each route-map command has a list of match and set commands associated with it. The match commands specify the match criteria—the conditions under which policy routing occurs. The set commands specify the set actions—the particular routing actions to perform if the criteria enforced by the match commands are met. You might want to policy route packets based on their source, for example, using an access list.

Examples

In the following example, routes that have addresses specified by access list numbers 5 or 80 will be matched:

route-map name

 match ip address 5 80

Route maps that use prefix lists can be used for route filtering, default origination, and redistribution in other routing protocols. In the following example, a default route 0.0.0.0/0 is conditionally originated when there exists a prefix 10.1.1.0/24 in the routing table:

ip prefix-list cond permit 10.1.1.0/24

!

route-map default-condition permit 10

match ip address prefix-list cond

!

router rip

default-information originate route-map default-condition

!

In the following policy routing example, packets that have addresses specified by access list numbers 6 or 25 will be routed to Ethernet interface 0:

interface serial 0

 ip policy route-map chicago

!

route-map chicago

 match ip address 6 25 

 set interface ethernet 0

Related Commands

match ip next-hop

To redistribute any routes that have a next hop router address passed by one of the access lists specified, use the match ip next-hop command in route-map configuration mode. To remove the next hop entry, use the no form of this command.

match ip next-hop {access-list-number | access-list-name} [...access-list-number | ...access-list-name]

no match ip next-hop {access-list-number | access-list-name} [...access-list-number | ...access-list-name]

Syntax Description

Defaults

Routes are distributed freely, without being required to match a next hop address.

Command Modes

Route-map configuration

Command History

Usage Guidelines

An ellipsis (...) in the command syntax indicates that your command input can include multiple values for the access-list-number or access-list-name argument.

Use the route-map global configuration command, and the match and set route-map configuration commands, to define the conditions for redistributing routes from one routing protocol into another. Each route-map command has a list of match and set commands associated with it. The match commands specify the match criteria—the conditions under which redistribution is allowed for the current route-map command. The set commands specify the set actions—the particular redistribution actions to perform if the criteria enforced by the match commands are met. The no route-map command deletes the route map.

The match route-map configuration command has multiple formats. The match commands can be given in any order, and all match commands must "pass" to cause the route to be redistributed according to the set actions given with the set commands. The no forms of the match commands remove the specified match criteria.

When you are passing routes through a route map, a route map can have several parts. Any route that does not match at least one match clause relating to a route-map command will be ignored; that is, the route will not be advertised for outbound route maps and will not be accepted for inbound route maps. If you want to modify only some data, you must configure a second route map section with an explicit match specified.

Examples

The following example distributes routes that have a next hop router address passed by access list 5 or 80 will be distributed:

route-map name

 match ip next-hop 5 80

Related Commands

match ip redistribution-source

To match the external Enhanced Interior Gateway Routing Protocol (EIGRP) routes that have been advertised by routers and access servers at the address specified by the access lists, use the match ip redistribution-source command in route-map configuration mode. To remove the redistribution-source entry, use the no form of this command.

match ip redistribution-source [access-list-number [...access-list-number]] [expanded-access-list [...expanded-access-list]] [access-list-name [...access-list-name]] [prefix-list name [...prefix-list name]]

no match ip redistribution-source [access-list-number [...access-list-number]] [expanded-access-list [...expanded-access-list]] [access-list-name [...access-list-name]] [prefix-list name [...prefix-list name]]

Syntax Description

Command Default

No filtering of the routes is applied on the redistribution source.

Command Modes

Route-map configuration (config-route-map)

Command History

Usage Guidelines

An ellipsis (...) in the command syntax indicates that your command input can include multiple values for the access-list-number argument, the expanded-access-list argument, the access-list-name argument, and the prefix-list name keyword and argument pair.

Use the route-map global configuration command, and the match and set route-map configuration commands, to define the conditions for redistributing routes from one routing protocol into another. Each route-map command has a list of match and set commands associated with it. The match commands specify the match criteria—the conditions under which redistribution is allowed for the current route-map command. The set commands specify the set actions—the particular redistribution actions to perform if the criteria enforced by the match commands are met. The no route-map command deletes the route map.

The match route-map configuration command has multiple formats. The match commands can be given in any order, and all match commands must "pass" to cause the route to be redistributed according to the set actions given with the set commands. The no forms of the match commands remove the specified match criteria.

Any route that does not match at least one match clause relating to a route-map command will be ignored; that is, the route will not be advertised for outbound route maps and will not be accepted for inbound route maps. If you want to modify only some data, you must configure the second route map section with an explicit match specified.

Examples

The following example shows how to filter the EIGRP routes that are advertised by routers and access servers at the address specified by access list 5 and expanded access list 1335:

Router(config)# route-map R1

Router(config-route-map)# match ip redistribution-source 5 1335

Related Commands

match ip route-source

To match routes that have been advertised by routers and access servers at the address specified by the access lists, use the match ip route-source command in route-map configuration mode. To remove the route-source entry, use the no form of this command.

match ip route-source [access-list-number [...access-list-number]] [expanded-access-list [...expanded-access-list]] [access-list-name [...access-list-name]] [prefix-list name [...prefix-list name]] [redistribution-source]

no match ip route-source [access-list-number [...access-list-number]] [expanded-access-list [...expanded-access-list]] [access-list-name [...access-list-name]] [prefix-list name [...prefix-list name]] [redistribution-source]

Syntax Description

Command Default

No filtering of the routes is applied on the route source.

Command Modes

Route-map configuration (config-route-map)

Command History

Usage Guidelines

An ellipsis (...) in the command syntax indicates that your command input can include multiple values for the access-list-number argument, the expanded-access-list argument, the access-list-name argument, and the prefix-list name keyword and argument pair.

Use the route-map global configuration command, and the match and set route-map configuration commands, to define the conditions for redistributing routes from one routing protocol into another. Each route-map command has a list of match and set commands associated with it. The match commands specify the match criteria—the conditions under which redistribution is allowed for the current route-map command. The set commands specify the set actions—the particular redistribution actions to perform if the criteria enforced by the match commands are met. The no route-map command deletes the route map.

The match route-map configuration command has multiple formats. The match commands can be given in any order, and all match commands must "pass" to cause the route to be redistributed according to the set actions given with the set commands. The no forms of the match commands remove the specified match criteria.

A route map can have several parts. Any route that does not match at least one match clause relating to a route-map command will be ignored; that is, the route will not be advertised for outbound route maps and will not be accepted for inbound route maps. If you want to modify only some data, you must configure the second route map section with an explicit match specified.

Examples

The following example shows how to match routes that are advertised by routers and access servers at the address specified by access list 5 and expanded access list 1335:

Router(config)# route-map R1

Router(config-route-map)# match ip route-source 5 1335

Related Commands

match length

To base policy routing on the Level 3 length of a packet, use the match length command in route-map configuration mode. To remove the entry, use the no form of this command.

match length minimum-length maximum-length

no match length minimum-length maximum-length

Syntax Description

Command Default

No policy routing occurs on the length of a packet.

Command Modes

Route-map configuration

Command History

Usage Guidelines

In IPv4, use the ip policy route-map interface configuration command, the route-map global configuration command, and the match and set route-map configuration commands, to define the conditions for policy routing packets. The ip policy route-map command identifies a route map by name. Each route-map has a list of match and set commands associated with it. The match commands specify the match criteria—the conditions under which policy routing occurs. The set commands specify the set actions—the particular routing actions to perform if the criteria enforced by the match commands are met.

In PBR for IPv6, use the ipv6 policy route-map or ipv6 local policy route-map command to define conditions for policy routing packets.

In IPv4, the match route-map configuration command has multiple formats. The match commands can be given in any order, and all match commands must "pass" to cause the packet to be routed according to the set actions given with the set commands. The no forms of the match commands remove the specified match criteria.

In IPv4, you might want to base your policy routing on the length of packets so that your interactive traffic and bulk traffic are directed to different routers.

Examples

In the following example, packets 3 to 200 bytes long, inclusive, will be routed to FDDI interface 0:

interface serial 0

 ip policy route-map interactive

!

route-map interactive

 match length 3 200

 set interface fddi 0

In the following example for IPv6, packets 3 to 200 bytes long, inclusive, will be routed to FDDI interface 0:

interface Ethernet0/0

  ipv6 policy-route-map interactive

!

route-map interactive

 match length 3 200

 set interface fddi 0

Related Commands

match metric (IP)

To redistribute routes with the specified metric, use the match metric command in route-map configuration mode. To remove the entry for the redistributed route from the routing table, use the no form of this command.

match metric {metric-value | external metric-value} [+- deviation-number]

no match metric {metric-value | external metric-value} [+- deviation-number]

Syntax Description

Command Default

No filtering is performed on a metric value.

Command Modes

Route-map configuration

Command History