To restore the default behavior of automatic summarization of subnet routes into network-level routes, use the auto-summary command in router configuration mode. Todisable this function and send subprefix routing information across classful network boundaries, use the no form of this command.

Syntax Description

This command has no arguments or keywords.

Command Default

Enabled (the software summarizes subprefixes to the classful network boundary when crossing classful network boundaries).

Command Modes

Router configuration

Command History

Usage Guidelines

Route summarization reduces the amount of routing information in the routing tables.

RIP Version 1 always uses automatic summarization. If you are using RIP Version 2, you can turn off automatic summarization by specifying the no auto-summary command. Disable automatic summarization if you must perform routing between disconnected subnets. When automatic summarization is off, subnets are advertised.

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.

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)

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.

Related Commands

To delete routes from the IPv6 Routing Information Protocol (RIP) routing table, use the clear ipv6 rip command in privileged EXEC mode.

Cisco IOS Release XE 3.9S, Cisco IOS Release 15.3(2)S, and Later Releases

Syntax Description

Command Modes

Privileged EXEC

Command History

Usage Guidelines

When the name argument is specified, only routes for the specified IPv6 RIP process are deleted from the IPv6 RIP routing table. If no name argument is specified, all IPv6 RIP routes are deleted.

Use the show ipv6 rip command to display IPv6 RIP routes.

Use the clear ipv6 rip name vrf vrf-name command to delete the specified VRF instances for the specified IPv6 RIP process.

Related Commands

To display debug messages for IPv6 Routing Information Protocol (RIP) transactions, use the debug ipv6 rip command in privileged EXEC mode. To disable debug messages for IPv6 RIP routing transactions, use the no form of this command.

Cisco IOS XE Release 3.9S, Cisco IOS Release 15.3(2)S, and Later Releases

Syntax Description

Command Modes

Privileged EXEC (#)

Command History

Usage Guidelines

The debug ipv6 rip command is similar to the debug ip rip command, except that it is IPv6-specific.

Note

By default, the network server sends the output from debug commands and system error messages to the console. To redirect debug output, use the logging command in global configuration mode. Destinations include the console, virtual terminals, internal buffer, and UNIX hosts running a syslog server. For complete information on debug commands and redirecting debug output, refer to the Cisco IOS Debug Command Reference.

Use the debug ipv6 rip command to enable IPv6 RIP debugging for RIP packets that are sent and received on all device interfaces. Use the debug ipv6 rip interface-type interface-number command to enable IPv6 RIP debugging for RIP packets that are sent and received only on the specified interface.

Use the debug ipv6 rip vrf vrf-name command to troubleshoot issues in the IPv6 RIP functionality when the VRF has already been enabled using a vrf definition vrf-name command. Ensure that the specified VRF name has already been defined. If a VRF name has not been defined, the following message is displayed:

% VRF <undefined VRF name> does not exist or does not have a RD.

Related Commands

To generate a default route into Routing Information Protocol (RIP), use the default-information originate command in router configuration mode. To disable this feature, use the no form of this command.

Syntax Description

Command Default

No default routes are generated into RIP.

Command Modes

Router configuration (config-router)

Command History

Usage Guidelines

The route map referenced in the default-information originate command cannot use an extended access list; it can use a standard access list.

When you configure the default-information originate on-passive command, RIP sends the default route on a passive interface. A default route is the network route with which a router communicates when no other known route exists for a given IP packet’s destination address. Before a RIP provider edge (PE) router can send the default route to the customer edge (CE) router, you must configure the interfaces facing the CE as passive interfaces by using the default-information originate on-passive command.

Once you configure the default-information originate on-passive command, the output of the show ip protocols command displays that RIP default routes are sent on passive interfaces.

Applying a condition to determine when the default route is originated is called conditional default origination.

Related Commands

To set default metric values for Routing Information Protocol ( RIP), use the default-metric command in router configuration mode. To return to the default state, use the no form of this command.

Syntax Description

Command Default

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

Command Modes

Router configuration

Command History

Usage Guidelines

T he default-metric command is used in conjunction with the redistribute router configuration command to cause the current routing protocol to use the same metric value for all redistributed routes. A default metric helps solve the problem of redistributing routes with incompatible metrics. Whenever metrics do not convert, using a default metric provides a reasonable substitute and enables the redistribution to proceed.

Related Commands

To suppress regularly scheduled flash updates, use the flash-update-threshold command in router configuration mode. To return to the default state, use the no form of this command.

Syntax Description

Command Default

This command is disabled by default.

Command Modes

Router configuration

Command History

Usage Guidelines

This command suppresses flash updates when the arrival of a regularly scheduled update matches the number of seconds that is configured with the seconds argument. The range of seconds that can be configure is from 0 to 30 seconds. If the number of seconds matches the number of seconds or is less than the number seconds that is configured with the seconds argument, the flash update is suppressed. If the numbers seconds until the flash update arrives exceeds the number of seconds that is configured with the seconds argument, the flash update is not suppressed. The regular scheduled interval for flash updates and the configuration of the suppression of flash updates can be verified with the show ip protocol command.

Related Commands

The input-queue command defines the number of received, but not yet processed RIP update packets contained in the Routing Information Protocol (RIP) input queue. Use the input-queuecommand in router configuration mode. To remove the configured depth and restore the default depth, use the no form of this command.

Syntax Description

Command Default

A depth of 50.

Command Modes

Router configuration

Command History

Usage Guidelines

Consider using the input-queue command if you have a high-end router that is sending at high speed to a low-speed router that might not be able to receive at the high speed. Configuring this command will help prevent the routing table from losing information.

Another way to prevent the routing table from losing information is to use the output-delay command to change the interpacket delay for RIP updates.

Related Commands

To configure the interval in which Routing Information Protocol (RIP) updates are advertised from a specific RIP-enabled interface, use the ip rip advertise command in interface configuration mode. To remove the configured interval in which RIP updates are advertised from a specific RIP-enabled interface, use the no form of this command.

Syntax Description

Command Default

RIP updates are advertised every 30 seconds, which is the default global periodic interval for a Cisco device.

Command Modes

Interface configuration (config-if)
        
      

Command History

Usage Guidelines

RIP uses broadcast UDP data packets to exchange routing information. RIP sends routing information updates every 30 seconds, which is the default global periodic advertisement interval for a Cisco device.

Use the ip rip advertise command to override the default global periodic advertisement interval on a specific RIP-enabled interface and configure the required periodic advertisement interval on that interface.

If you have to configure a specific periodic advertisement interval on all RIP-enabled interfaces in a Cisco device, use the timers basic command. If you have to configure a specific periodic advertisement interval on a specific interface, use the ip rip advertise command.

Related Commands

To enable authentication for Routing Information Protocol (RIP) Version 2 packets and to specify the set of keys that can be used on an interface, use the ip rip authentication key-chain command in interface configuration mode. To prevent authentication, use the no form of this command.

Syntax Description

Command Default

No authentication is provided for RIP packets.

Command Modes

Interface configuration

Command History

Usage Guidelines

If no key chain is configured with the key-chain command, no authentication is performed on the interface (not even the default authentication).

Related Commands

To specify the type of authentication used in Routing Information Protocol (RIP) Version 2 packets, use the ip rip authentication mode command in interface configuration mode. To restore clear text authentication, use the no form of this command.

Syntax Description

Command Default

Clear text authentication is provided for RIP packets.

Command Modes

Interface configuration

Command History

Usage Guidelines

RIP Version 1 does not support authentication.

Related Commands

To delay the initiation of RIPv2 neighbor sessions using MD5 authentication until the network connectivity between the neighbor routers is fully operational, use the ip rip initial-delay command in interface, or subinterface configuration mode. To remove the configured delay, use the no form of this command.

Syntax Description

Command Default

The delay of RIPv2 neighbor sessions is not configured.

Command Modes

Interface configuration (config-if)
Subinterface configuration (config-subif)

Command History

Usage Guidelines

Some non-Cisco routers will not allow an MD5-authenticated RIPv2 neighbor session to start when the sequence number of the first MD5 packet received from the Cisco router is greater than 0. The IP-RIP Delay Start feature is used on Cisco routers to delay the initiation of RIPv2 neighbor sessions using MD5 authentication until the network connectivity between the neighbor routers is fully operational. This ensures the sequence number of the first MD5 packet that the router sends to the non-Cisco neighbor router is 0.

Related Commands

To specify a Routing Information Protocol ( RIP) version to receive on an interface basis, use the ip rip receive version command in interface configuration mode. To follow the global version rules, use the no form of this command.

Syntax Description

Command Default

This command is disabled by default.

Command Modes

Interface configuration

Command History

Usage Guidelines

Use this command to override the default behavior of RIP as specified by the version command. This command applies only to the interface being configured. You can configure the interface to accept both RIP versions.

Related Commands

To specify a Routing Information Protocol ( RIP) version to send on an interface basis, use the ip rip send version command in interface configuration mode. To follow the global version rules, use the no form of this command.

Syntax Description

Command Default

This command is disabled by default.

Command Modes

Interface configuration

Command History

Usage Guidelines

Use this command to override the default behavior of RIP as specified by the version command. This command applies only to the interface being configured.

Related Commands

To enable triggered extensions to Routing Information Protocol (RIP), use the ip rip triggered command in interface configuration mode. To disable triggered extensions to RIP, use the no form of this command.

Syntax Description

This command has no arguments or keywords.

Command Default

This command is disabled by default.

Command Modes

Interface configuration

Command History

Usage Guidelines

When triggered extensions to RIP are enabled, routing updates are sent on the WAN only if one of the following events occurs:

• The router receives a specific request for a routing update. (Full database is sent.)

• Information from another interface modifies the routing database. (Only latest changes are sent.)

• The interface comes up or goes down. (Partial database is sent.)

• The router is first powered on, to ensure that at least one update is sent. (Full database is sent.)

You might want to enable this feature if you are using an on-demand circuit and you are charged for usage time. Fewer routing updates will incur lower usage costs.

Entries in the routing database can be either temporary or semipermanent. Entries learned from broadcasts on LANs are temporary; they will expire if not periodically refreshed by more broadcasts.

Entries learned from a triggered response on the WAN are semipermanent; they do not time out like other entries. Certain events can cause these routes to time out, such as the interface going down, or if the outgoing interface is the same as the incoming interface. Neighbor updates of the routes with a metric of 16 (infinity) mean the route is unreachable, and those routes are eventually removed from the routing table.

Related Commands

To allow Routing Information Protocol (RIP) Version 2 update packets to be sent as broadcast packets instead of multicast packets, use the ip rip v2-broadcast command in interface configuration mode. To disable the broadcast of IP RIP Version 2 update packets that are sent as broadcast packets, use the no form of this command.

Syntax Description

This command has no arguments or keywords.

Command Default

This command is disabled by default. Unless the ip rip v2-broadcast commend is entered, RIP Version 2 update packets are sent as multicast packets.

Command Modes

Interface configuration (config-if)

Command History

Usage Guidelines

Use the ip rip v2-broadcast command to broadcast RIP Version 2 broadcast updates to hosts that do not listen to multicast broadcasts. Version 2 updates (requests and responses) will be sent to the IP broadcast address 255.255.255.255 instead of the IP multicast address 224.0.0.9.

In order to reduce unnecessary load on those hosts that are not listening to RIP Version 2 broadcasts, the system uses an IP multicast address for periodic broadcasts. The IP multicast address is 224.0.0.9.

Note	It is not necessary to configure Internet Group Management Protocol (IGMP) because the periodic broadcasts are interrouter messages that are not forwarded.

Related Commands

To enable the split horizon mechanism, use the ip split-horizon command in interface configuration mode. To disable the split horizon mechanism, use the no form of this command.

Syntax Description

This command has no arguments or keywords.

Command Default

Default behavior varies with media type.

Command Modes

Interface configuration

Command History

Usage Guidelines

For all interfaces except those for which either Frame Relay or Switched Multimegabit Data Service (SMDS) encapsulation is enabled, the default condition for this command is ip split-horizon; in other words, the split horizon feature is active. If the interface configuration includes either the encapsulation frame-relay or encapsulation smds command, then the default is for split horizon to be disabled. Split horizon is not disabled by default for interfaces using any of the X.25 encapsulations.

Note

For networks that include links over X.25 packet switched networks (PSNs), the neighbor router configuration command can be used to defeat the split horizon feature. You can as an alternative explicitly specify the no ip split-horizon command in your configuration. However, if you do so you must similarly disable split horizon for all routers in any relevant multicast groups on that network.

Note	If split horizon has been disabled on an interface and you want to enable it, use the ip split-horizon command to restore the split horizon mechanism.

Note

In general, changing the state of the default for the ip split-horizon command is not recommended, unless you are certain that your application requires a change in order to properly advertise routes. If split horizon is disabled on a serial interface (and that interface is attached to a PSN), you must disable split horizon for all routers and access servers in any relevant multicast groups on that network.

Related Commands

To configure a summary aggregate address under an interface for the Routing Information Protocol (RIP), use the ip summary-address rip command in interface configuration mode. To disable summarization of the specified address or subnet, use the no form of this command.

Syntax Description

Command Default

RIP automatically summarizes to classful network boundaries.

Command Modes

Interface configuration

Command History

Usage Guidelines

The ip summary-address rip command is used to summarize an address or subnet under a specific interface. RIP automatically summarizes to classful network boundaries. Only one summary address can be configured for each classful subnet.

Related Commands

To enable VRF-aware support for IPv6 Routing Information Protocol (RIP), use the ipv6 rip vrf-mode enable command in global configuration mode. To disable VRF-aware support for IPv6 RIP, use the no form of this command.

Syntax Description

This command has no arguments or keywords.

Command Default

VRF-aware support is not enabled in IPv6 RIP.

Command Modes

Global configuration (config)

Usage Guidelines

When VRF-aware support is enabled in IPv6 RIP, you can configure only one RIP instance at a given time. More than one RIP instance is not allowed.

Related Commands

To define a neighboring router for exchanging routing information, use the neighbor command in router configuration mode. To remove a neighboring router entry, use the no form of this command.

Syntax Description

Command Default

No neighboring routers are defined.

Command Modes

Router configuration (config-router)

Command History

Usage Guidelines

This command permits point-to-point (nonbroadcast) exchange of routing information. When it is used in combination with the passive-interface command, routing information can be exchanged between a subset of routers and access servers on a LAN.

Use multiple neighbor commands to specify additional neighbors or peers.

Related Commands

To specify a list of networks for the Routing Information Protocol (RIP) routing process, use the network command in router configuration mode. To remove an entry, use the no form of this command.

Syntax Description

Command Default

No networks are specified.

Command Modes

Router configuration

Command History

Usage Guidelines

The network number specified must not contain any subnet information. There is no limit to the number of network commands you can use on the router. RIP routing updates will be sent and received only through interfaces on this network.

RIP sends updates to the interfaces in the specified networks. Also, if the network of an interface is not specified, the interface will not be advertised in any RIP update.

Related Commands

To add an offset to incoming and outgoing metrics to routes learned via Routing Information Protocol (RIP), use the offset-listcommand in router configuration mode. To remove an offset list, use the no form of this command.

Syntax Description

Command Default

This command is disabled by default.

Command Modes

Router configuration

Command History

Usage Guidelines

The offset value is added to the routing metric. An offset list with an interface type and interface number is considered extended and takes precedence over an offset list that is not extended. Therefore, if an entry passes the extended offset list and the normal offset list, the offset of the extended offset list is added to the metric.

To change the interpacket delay for Routing Information Protocol (RIP) updates sent, use the output-delay command in router configuration mode. To remove the delay, use the no form of this command.

Syntax Description

Command Default

The default interpacket delay is 0 milliseconds.

Command Modes

Router configuration

Command History

Usage Guidelines

Consider using this command if you have a high-end router that is sending at high speed to a low-speed router that might not be able to receive at the high speed. Configuring this command will help prevent the routing table from losing information.

To configure the Routing Information Protocol (RIP) routing process, use the route r rip command in global configuration mode. To turn off the RIP routing process, use the no form of this command.

Syntax Description

This command has no arguments or keywords.

Command Default

No RIP routing process is defined.

Command Modes

Global configuration

Command History

Related Commands

To enable the delivery of RIP update messages from a Cisco IOS router containing an integrated cable modem or a cable modem HWIC to a Hybrid Fiber-Coaxial (HFC) CMTS when they are on different subnets, use the service-module ip rip relay command in interface configuration mode. To disable RIP relay, use the no form of this command.

Syntax Description

This command has no keywords or arguments.

Command Default

RIP relay is disabled.

Command Modes

Interface configuration (config-if)

Command History

Usage Guidelines

The service-module ip rip relay command is used to enable the HFC RIP Relay feature that allows the delivery of RIP messages from a Cisco IOS router containing an integrated cable modem or a cable modem High-Speed WAN Interface Card (HWIC) to the Cable Modem Termination system (CMTS) when they are on different subnets. In Cisco IOS releases prior to 12.4(15)XY and 12.4(20)T, RIP messages were rejected by the CMTS because the interface on the Cisco IOS router was in a different subnet from the CMTS.

Related Commands

To display summary address entries in the Routing Information Protocol (RIP) routing database entries if relevant are routes being summarized based upon a summary address, use the show ip rip database command in privileged EXEC mode.

Syntax Description

Command Default

No default behavior or values.

Command Modes

Privileged EXEC

Command History

Usage Guidelines

Summary address entries will appear in the database only if relevant child routes are being summarized. When the last child route for a summary address becomes invalid, the summary address is also removed from the routing table.

The RIP private database is populated only if triggered extensions to RIP are enabled with the ip rip triggered command.

Related Commands

To display Routing Information Protocol (RIP) neighbors for which Bidirectional Forwarding Detection (BFD) sessions are created, use the show ip rip neighbors command in privileged EXEC mode.

Syntax Description

This command has no argument or keywords.

Command Modes

Privileged EXEC (#)

Command History

Usage Guidelines

Use the show ip rip neighbors command to display RIP neighbors for which BFD sessions are created.

Related Commands

To display information about current IPv6 Routing Information Protocol (RIP) processes, use the show ipv6 rip command in user EXEC or privileged EXEC mode.

Cisco IOS XE Release 3.9S, Cisco IOS Release 15.3(2)S, and Later Releases