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Use the commands in this chapter to configure and monitor Routing Information Protocol (RIP). For RIP configuration information and examples, refer to the "Configuring RIP" chapter of the Cisco IOS IP and IP Routing Configuration Guide.
To restore the default behavior of automatic summarization of subnet routes into network-level routes, use the auto-summary router configuration command. To disable this function and send subprefix routing information across classful network boundaries, use the no form of this command.
auto-summarySyntax Description
This command has no arguments or keywords.
Defaults
Enabled (the software summarizes subprefixes to the classful network boundary when crossing classful network boundaries).
Command Modes
Router configuration
Command History
10.0 This command was introduced.
Release
Modification
Usage Guidelines
Route summarization reduces the amount of routing information in the routing tables.
Examples
In the following example, network numbers are not summarized automatically:
router rip version 2 no auto-summary
To generate a default route into Routing Information Protocol (RIP), use the default-information originate router configuration command. To disable this feature, use the no form of this command.
default-information originate [route-map mapname]
Syntax Description
route-map mapname (Optional) Routing process will generate the default route if the route map is satisfied.
Defaults
Disabled
Command Modes
Router configuration
Command History
11.2 This command was introduced.
Release
Modification
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.
Examples
The following example originates a default route (0.0.0.0/0) over a certain interface when 172.68.0.0/16 is present. Applying a condition (in this case a route map) to determine when the default route is originated is called "conditional default origination."
router rip version 2 network 172.68.16.0 default-information originate route-map condition ! route-map condition permit 10 match ip address 10 set interface s1/0 ! access-list 10 permit 172.68.16.0 0.0.0.255 !
To set default metric values for Routing Information Protocol (RIP), use the default-metric router configuration command. To return to the default state, use the no form of this command.
default-metric number
Syntax Description
number Default metric value.
Defaults
Built-in, automatic metric translations, as appropriate for each routing protocol
Command Modes
Router configuration
Command History
10.0 This command was introduced.
Release
Modification
Usage Guidelines
The default-metric command is used in conjunction with the redistribute router configuration command to cause the current routing protocol to use the same metric value for all redistributed routes. A default metric helps solve the problem of redistributing routes with incompatible metrics. Whenever metrics do not convert, using a default metric provides a reasonable substitute and enables the redistribution to proceed.
Examples
The following example shows a router in autonomous system 109 using both the RIP and the OSPF routing protocols. The example advertises OSPF-derived routes using the RIP protocol and assigns the OSPF-derived routes a RIP metric of 10.
router rip default-metric 10 redistribute ospf 109
Related Commands
redistribute (IP) Redistributes routes from one routing domain into another routing domain.
Command
Description
Syntax Description
name-of-chain Enables authentication and specifies the group of keys that are valid.
Defaults
No authentication is provided for RIP packets.
Command Modes
Interface configuration
Command History
11.1 This command was introduced.
Release
Modification
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).
Examples
The following example configures the interface to accept and send any key belonging to the key chain named trees:
ip rip authentication key-chain trees
Related Commands
key chain Enables authentication for routing protocols.
Command
Description
Syntax Description
text Clear text authentication. md5 Keyed MD5 authentication.
Defaults
Clear text authentication is provided for RIP packets.
Command Modes
Interface configuration
Command History
11.1 This command was introduced.
Release
Modification
Usage Guidelines
RIP Version 1 does not support authentication.
Examples
The following example configures the interface to use MD5 authentication:
ip rip authentication mode md5
Related Commands
Enables authentication for RIP Version 2 packets and specifies the set of keys that can be used on an interface. key chain Enables authentication for routing protocols.
Command
Description
To specify a Routing Information Protocol (RIP) version to receive on an interface basis, use the ip rip receive version interface configuration command. To follow the global version rules, use the no form of this command.
ip rip receive version [1] [2]
Syntax Description
1 (Optional) Accepts only RIP Version 1 packets on the interface. 2 (Optional) Accepts only RIP Version 2 packets on the interface.
Defaults
The software behaves according to the version command.
Command Modes
Interface configuration
Command History
11.1 This command was introduced.
Release
Modification
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.
Examples
The following example configures the interface to receive both RIP Version 1 and Version 2 packets:
ip rip receive version 1 2
The following example configures the interface to receive only RIP Version 1 packets:
ip rip receive version 1
Related Commands
Specifies a RIP version to send on an interface basis. Specifies a RIP version used globally by the router. Enables authentication for RIP Version 2 packets and specifies the set of keys that can be used on an interface. key chain Enables authentication for routing protocols.
Command
Description
To specify a Routing Information Protocol (RIP) version to send on an interface basis, use the ip rip send version interface configuration command. To follow the global version rules, use the no form of this command.
ip rip send version [1] [2]
Syntax Description
1 (Optional) Sends only RIP Version 1 packets out the interface. 2 (Optional) Sends only RIP Version 2 packets out the interface.
Defaults
The software behaves according to the router version command.
Command Modes
Interface configuration
Command History
11.1 This command was introduced.
Release
Modification
Usage Guidelines
Use this command to override the default behavior of RIP as specified by the router version command. This command applies only to the interface being configured.
Examples
The following example configures the interface to send both RIP Version 1 and Version 2 packets out the interface:
ip rip send version 1 2
The following example configures the interface to send only RIP Version 2 packets out the interface:
ip rip send version 2
Related Commands
Specifies a RIP version to receive on an interface basis. Specifies a RIP version used globally by the router.
Command
Description
To enable triggered extensions to Routing Information Protocol (RIP), use the ip rip triggered interface configuration command. To disable triggered extensions to RIP, use the no form of this command.
ip rip triggeredSyntax Description
This command has no arguments or keywords.
Defaults
The software behaves according to the router version command.
Command Modes
Interface configuration
Command History
12.0(1)T This command was introduced.
Release
Modification
Usage Guidelines
When triggered extensions to RIP are enabled, routing updates are transmitted on the WAN only if one of the following 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.
Examples
The following example enables triggered extensions to RIP:
interface serial 0 ip rip triggered
Related Commands
show ip rip database Displays the contents of the RIP private database when triggered extensions to RIP are enabled.
Command
Description
To enable the split horizon mechanism, use the ip split-horizon interface configuration command. To disable the split horizon mechanism, use the no form of this command.
ip split-horizonSyntax Description
This command has no arguments or keywords.
Defaults
Varies with media
Command Modes
Interface configuration
Command History
10.0 This command was introduced.
Release
Modification
Usage Guidelines
For all interfaces except those for which either Frame Relay or 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 commands, 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.
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Note For networks that include links over X.25 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. |
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Note If split horizon has been disabled on an interface and you wish to enable it, use the ip split-horizon command to restore the split horizon mechanism. |
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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 packet-switched network), you must disable split horizon for all routers and access servers in any relevant multicast groups on that network. |
The following simple example disables split horizon on a serial link. The serial link is connected to an X.25 network:
interface serial 0 encapsulation x25 no ip split-horizon
Related Commands
Defines a neighboring router with which to exchange routing information.
Command
Description
To configure a Cisco router running Routing Information Protocol (RIP) to advertise a summarized local IP address pool on a network access server so that the address pool can be provided to dialup clients and specify the IP address and network mask that identify the routes to be summarized, use the ip summary-address rip router configuration command. To disable the split horizon mechanism, use the no form of this command.
ip summary-address rip ip-address ip-network-mask
Syntax Description
ip-address IP address to be summarized. ip-network-mask IP network mask that drives route summarization for the specified IP address.
Defaults
No default behavior or values.
Command Modes
Router configuration
Command History
12.0(6)T This command was introduced.
Release
Modification
Usage Guidelines
The host name entries are not removed from NVRAM but are cleared in running memory.
Examples
In the following example the major net is 10.0.0.0. The summary address 10.2.0.0 overrides the autosummary address of 10.0.0.0, so that 10.2.0.0 is advertised out interface e1 and 10.0.0.0 is not advertised.
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Note If split horizon is enabled, neither autosummary nor interface summary addresses (those configured with the ip summary-address rip command) are advertised. |
router rip router int e1 ip address 10.1.1.1 255.255.255.0 (config-if)# ip summary-address rip 10.2.0.0 255.255.0.0 no ip split-horizon router rip network 10.0.0.0 neighbor 2.2.2.2 peer-group mygroup
Related Commands
Restores the default behavior of automatic summarization of subnet routes into network-level routes. Enables the split horizon mechanism.
Command
Description
To define a neighboring router with which to exchange routing information, use the neighbor router configuration command. To remove an entry, use the no form of this command.
neighbor ip-address
Syntax Description
ip-address IP address of a peer router with which routing information will be exchanged.
Defaults
No neighboring routers are defined.
Command Modes
Router configuration
Command History
10.0 This command was introduced.
Release
Modification
Usage Guidelines
This command permits the point-to-point (nonbroadcast) exchange of routing information. When used in combination with the passive-interface router configuration command, routing information can be exchanged between a subset of routers and access servers on a LAN.
Multiple neighbor commands can be used to specify additional neighbors or peers.
Examples
In the following example, RIP updates are sent to all interfaces on network 131.108.0.0 except interface Ethernet 1. However, in this case a neighbor router configuration command is included. This command permits the sending of routing updates to specific neighbors. One copy of the routing update is generated per neighbor.
router rip network 131.108.0.0 passive-interface ethernet 1 neighbor 131.108.20.4
Related Commands
passive-interface Disables sending routing updates on an interface.
Command
Description
To specify a list of networks for the Routing Information Protocol (RIP) routing process, use the network router configuration command. To remove an entry, use the no form of this command.
network network-number
Syntax Description
network-number IP address of the network of directly connected networks.
Defaults
No networks are specified.
Command Modes
Router configuration
Command History
10.0 This command was introduced.
Release
Modification
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 an interface's network is not specified, it will not be advertised in any RIP update.
Examples
The following example defines RIP as the routing protocol to be used on all interfaces connected to networks 128.99.0.0 and 192.31.7.0:
router rip network 128.99.0.0 network 192.31.7.0
Related Commands
Configures the RIP routing process.
Command
Description
To add an offset to incoming and outgoing metrics to routes learned via Routing Information Protocol (RIP), use the offset-list router configuration command. To remove an offset list, use the no form of this command.
offset-list {access-list-number | name} {in | out} offset [type number]
Syntax Description
access-list-number | name Standard access list number or name to be applied. Access list number 0 indicates all access lists. If offset is 0, no action is taken. For IGRP, the offset is added to the delay component only. in Applies the access list to incoming metrics. out Applies the access list to outgoing metrics. offset Positive offset to be applied to metrics for networks matching the access list. If the offset is 0, no action is taken. type (Optional) Interface type to which the offset-list is applied. number (Optional) Interface number to which the offset-list is applied.
Defaults
Disabled
Command Modes
Router configuration
Command History
10.0 This command was introduced. 10.3 The type and number arguments were added. 11.2 The name argument was added.
Release
Modification
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 extended offset-list's offset is added to the metric.
Examples
In the following example, the router applies an offset of 10 to the router's delay component only to access list 21:
offset-list 21 out 10
In the following example, the router applies an offset of 10 to routes learned from Ethernet interface 0:
offset-list 21 in 10 ethernet 0
To change the interpacket delay for Routing Information Protocol (RIP) updates sent, use the output-delay router configuration command. To remove the delay, use the no form of this command.
output-delay delay
Syntax Description
delay Delay, in milliseconds, between packets in a multiple-packet RIP update. The range is 8 to 50 milliseconds. The default is no delay.
Defaults
0 milliseconds
Command Modes
Router configuration
Command History
10.0 This command was introduced.
Release
Modification
Usage Guidelines
Consider using this command if you have a high-end router sending at high speed to a low-speed router that might not be able to receive at that fast a rate. Configuring this command will help prevent the routing table from losing information.
Examples
The following example sets the interpacket delay to 10 milliseconds:
output-delay 10
To configure the Routing Information Protocol (RIP) routing process, use the router rip global configuration command. To turn off the RIP routing process, use the no form of this command.
router ripSyntax Description
This command has no arguments or keywords.
Defaults
No RIP routing process is defined.
Command Modes
Global configuration
Command History
10.0 This command was introduced.
Release
Modification
Examples
The following example shows how to begin the RIP routing process:
router rip
Related Commands
Specifies a list of networks for the RIP process.
Command
Description
To display summary address entries in the Routing Information Protocol (RIP) routing database entries if there are relevant routes being summarized based upon a summary address, use the show ip rip database EXEC command.
show ip rip databaseSyntax Description
This command has no arguments or keywords.
Defaults
No default behavior or values.
Command Modes
EXEC
Command History
12.0(6)T This command was introduced.
Release
Modification
Usage Guidelines
Summary address entries will appear in the database only if there are relevant child routes 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.
Examples
The following example shows output with a summary address entry for route 12.11.0.0/16, with three child routes active:
router# show ip rip database 11.0.0.0/8 auto-summary 11.11.11.0/24 directly connected, Ethernet2 12.0.0.0/8 auto-summary 12.11.0.0/16 int-summary ^^^^^^^^^^^^^^^^^^^^^^^^^^^ 12.11.10.0/24 directly connected, Ethernet3 12.11.11.0/24 directly connected, Ethernet4 12.11.12.0/24 directly connected, Ethernet5
The following is sample output of the show ip rip database command with a prefix and mask:
Router# show ip rip database 172.19.86.0 255.255.255.0
172.19.86.0/24
[1] via 172.19.67.38, 00:00:25, Serial0
[1] via 172.19.70.36, 00:00:14, Serial1
Table 42 describes the fields in the displays.
| Field | Description |
|---|---|
172.19.0.0/16 auto-summary | Summary address entry. |
172.19.64.0/24 directly connected, Ethernet0 | Directly connected entry for Ethernet 0. |
172.19.65.0/24 [1] via 172.19.70.36, 00:00:17, Serial1 [2] via 172.19.67.38, 00:00:25, Serial0 | The destination 172.19.65.0/24 is learned via RIP. There are two sources advertising it. One is 172.19.70.36 via Serial interface 1, and it was updated 17 seconds ago. The other source is 172.19.67.38 via Serial interface 0, and it was updated 25 seconds ago. |
Related Commands
Enables triggered extensions of RIP. Configures a Cisco router running RIPv2 to advertise a summarized local IP address pool on a network access server so that the address pool can be provided to dialup clients, and specifies the IP address and network mask that identify the routes to be summarized. show ip protocols Displays the parameters and current state of the active routing protocol process.
Command
Description
To adjust RIP network timers, use the timers basic router configuration command. To restore the default timers, use the no form of this command.
timers basic update invalid holddown flush
Syntax Description
update Rate in seconds at which updates are sent. This is the fundamental timing parameter of the routing protocol. The default is 30 seconds. invalid Interval of time in seconds after which a route is declared invalid; it should be at least three times the value of update. A route becomes invalid when there is an absence of updates that refresh the route. The route then enters holddown. The route is marked inaccessible and advertised as unreachable. However, the route is still used for forwarding packets. The default is 180 seconds. holddown Interval in seconds during which routing information regarding better paths is suppressed. It should be at least three times the value of update. A route enters into a holddown state when an update packet is received that indicates the route is unreachable. The route is marked inaccessible and advertised as unreachable. However, the route is still used for forwarding packets. When holddown expires, routes advertised by other sources are accepted and the route is no longer inaccessible. The default is 180 seconds. flush Amount of time in seconds that must pass before the route is removed from the routing table; the interval specified should be greater than the invalid value. If it is less than this sum, the proper holddown interval cannot elapse, which results in a new route being accepted before the holddown interval expires. The default is 240 seconds.
Defaults
update is 30 seconds.
invalid is 180 seconds.
holddown is 180 seconds.
flush is 240 seconds.
Command Modes
Router configuration
Command History
10.0 This command was introduced.
Release
Modification
Usage Guidelines
The basic timing parameters for RIP are adjustable. Because RIP is executing a distributed, asynchronous routing algorithm, it is important that these timers be the same for all routers and access servers in the network.
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Note The current and default timer values can be seen by inspecting the output of the show ip protocols EXEC command. The relationships of the various timers should be preserved as described previously. |
Examples
The following example sets updates to be broadcast every 5 seconds. If a router is not heard from in 15 seconds, the route is declared unusable. Further information is suppressed for an additional 15 seconds. At the end of the suppression period, the route is flushed from the routing table.
router rip timers basic 5 15 15 30
Note that by setting a short update period, you run the risk of congesting slow-speed serial lines. A short update period concern on faster-speed Ethernets and T1-rate serial lines. Also, if you have many routes in your updates, you can cause the routers to spend an excessive amount of time processing updates.
To have the Cisco IOS software validate the source IP address of incoming routing updates for Routing Information Protocol (RIP) and Interior Gateway Routing Protocol (IGRP) routing protocols, use the validate-update-source router configuration command. To disable this function, use the no form of this command.
validate-update-sourceSyntax Description
This command has no arguments or keywords.
Defaults
Enabled
Command Modes
Router configuration
Command History
10.0 This command was introduced.
Release
Modification
Usage Guidelines
This command is only applicable to RIP and IGRP. The software ensures that the source IP address of incoming routing updates is on the same IP network as one of the addresses defined for the receiving interface.
Disabling split horizon on the incoming interface will also cause the system to perform this validation check.
For unnumbered IP interfaces (interfaces configured as ip unnumbered), no checking is performed.
Examples
The following example configures a router not to perform validation checks on the source IP address of incoming RIP updates:
router rip network 128.105.0.0 no validate-update-source
Syntax Description
1 Specifies RIP Version 1. 2 Specifies RIP Version 2.
Defaults
The software receives RIP Version 1 and Version 2 packets, but sends only Version 1 packets.
Command Modes
Router configuration
Command History
11.1 This command was introduced.
Release
Modification
Usage Guidelines
To specify RIP versions used on an interface basis, use the ip rip receive version and ip rip send version commands.
Examples
The following example enables the software to send and receive RIP Version 2 packets:
version 2
Related Commands
Specifies a RIP version to receive on an interface basis. Specifies a RIP version to send on an interface basis. show ip protocols Displays the parameters and current state of the active routing protocol process.
Command
Description
Posted: Mon Aug 14 11:32:58 PDT 2000
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