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Cisco IOS IP Routing Protocols Command Reference
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Introduction
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BGP Commands: A through B
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BGP Commands: C through I
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BGP Commands: M through neighbor soo
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BGP Commands: neighbor timers through show bgp nsap summary
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BGP Commands: show ip bgp through T
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EIGRP Commands: A through I
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EIGRP Commands: M through V
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Integrated IS-IS Commands: A through I
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Integrated IS-IS Commands: L through V
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On-Demand Routing Commands
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OSPF Commands: A through ip ospf demand-circuit
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OSPF Commands: ip ospf flood-reduction through R
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OSPF Commands: show ip ospf through T
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IP Routing Protocol-Independent Commands: A through R
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IP Routing Protocol-Independent Commands: S through T
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RIP Commands
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Table Of Contents
Routing Information Protocol Commands
default-information originate (RIP)
ip rip authentication key-chain
Routing Information Protocol Commands
auto-summary (RIP)
To restore the default behavior of automatic summarization of subnet routes into network-level routes, use the auto-summary command in router configuration mode. To disable this function and send subprefix routing information across classful network boundaries, use the no form of this command.
auto-summary
no auto-summary
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.
Examples
In the following example, network numbers are not summarized automatically:
router ripversion 2no auto-summarydefault-information originate (RIP)
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.
default-information originate [route-map map-name]
no default-information originate
Syntax Description
route-map map-name
(Optional) Routing process will generate the default route if the route map is satisfied.
Command Default
No default routes are generated into RIP.
Command Modes
Router configuration
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.
Examples
The following example originates a default route (0.0.0.0/0) over a certain interface when 172.17.0.0/16 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 ripversion 2network 172.17.16.0default-information originate route-map condition!route-map condition permit 10match ip address 10set interface s1/0!access-list 10 permit 172.17.16.0 0.0.0.255!default-metric (RIP)
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.
default-metric number-value
no default-metric [number-value]
Syntax Description
Defaults
Built-in, automatic metric translations, as appropriate for each routing protocol
Command Modes
Router configuration
Command History
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 Open Shortest Path First (OSPF) routing protocols. The example advertises OSPF-derived routes using RIP and assigns the OSPF-derived routes a RIP metric of 10.
router ripdefault-metric 10redistribute ospf 109Related Commands
redistribute (IP)
Redistributes routes from one routing domain into another routing domain.
flash-update-threshold
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.
flash-update-threshold seconds
no flash-update-threshold
Syntax Description
seconds
The time interval in seconds for which the suppression of flash updates can be configured. The range is from 1 to 30 seconds.
Defaults
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.
Examples
The following example configures a router to suppress a regularly scheduled flash update if the update is due in 10 seconds or less:
router ripflash-update-threshold 10Related Commands
show ip protocols
Displays the parameters and current state of the active routing protocol process.
input-queue
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-queue command in router configuration mode. To remove the configured depth and restore the default depth, use the no form of this command.
input-queue depth
no input-queue
Syntax Description
Defaults
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.
Examples
The following example sets the depth of the RIP input queue to 100:
router ripinput-queue 100Related Commands
ip rip authentication key-chain
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.
ip rip authentication key-chain name-of-chain
no ip rip authentication key-chain [name-of-chain]
Syntax Description
Defaults
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).
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 treesRelated Commands
ip rip authentication mode
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.
ip rip authentication mode {text | md5}
no ip rip authentication mode
Syntax Description
Defaults
Clear text authentication is provided for RIP packets.
Command Modes
Interface configuration
Command History
Usage Guidelines
RIP Version 1 does not support authentication.
Examples
The following example configures the interface to use MD5 authentication:
ip rip authentication mode md5Related Commands
ip rip initial-delay
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.
ip rip initial-delay delay
no ip rip initial-delay
Syntax Description
delay
The number of seconds to wait before sending the first MD5 authentication packet to the RIPv2 neighbor. Range: 0 to 1800.
Command Default
This command is not enabled by default.
Command Modes
Interface
Subinterface configurationCommand 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 thereby ensuring that the sequence number of the first MD5 packet that the router sends to the non-Cisco neighbor router is 0.
Examples
The following example configures the router to wait 45 seconds before sending the first MD5 authentication packet to a non-Cisco device:
Router(config)# interface serial 3/0.1Router(config-subif)# ip rip initial-delay 45Related Commands
ip rip receive version
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.
ip rip receive version [1] [2]
no ip rip receive version
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
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.
Examples
The following example configures the interface to receive both RIP Version 1 and Version 2 packets:
ip rip receive version 1 2The following example configures the interface to receive only RIP Version 1 packets:
ip rip receive version 1Related Commands
ip rip send version
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.
ip rip send version [1] [2]
no ip rip send version
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
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.
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 2The following example configures the interface to send only RIP Version 2 packets out the interface:
ip rip send version 2Related Commands
ip rip receive version
Specifies a RIP version to receive on an interface basis.
version
Specifies a RIP version used globally by the router.
ip rip triggered
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.
ip rip triggered
no ip rip triggered
Syntax Description
This command has no arguments or keywords.
Defaults
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:
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The router receives a specific request for a routing update. (Full database is sent.)
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•
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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 0ip rip triggeredRelated Commands
show ip rip database
Displays the contents of the RIP private database when triggered extensions to RIP are enabled.
ip rip v2-broadcast
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.
ip rip v2-broadcast
no ip rip v2-broadcast
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
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 244.0.0.9.
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 244.0.0.9.
Note
Examples
The following example configures Version 2 IP broadcast updates on RIP Ethernet interface 3/1:
Router(config) interface ethernet3/1Router(config-if) ip address 172.16.1.1 255.255.255.0Router(config-if) ip rip v2-broadcast...Router(config-if) router ripRouter(config-if) version 2Router(config-if) network 172.0.0.0Enter debug ip rip command to verify that RIP Version 2 IP broadcast updates are being sent to the IP broadcast address 255.255.255 instead of IP multicast address 244.0.0.9:
Router# debug ip rip14:41:59: RIP: sending v2 update to 255.255.255.255 via Ethernet3/1 (172.16.1.1)If the ip rip v2-broadcast command has not been entered, the output from the debug ip rip command verifies that the RIP Version 2 IP broadcast updates are being sent to the IP multicast address 244.0.0.9:
Router# debug ip rip15:45:16: RIP: sending v2 update to 244.0.0.9 via Ethernet3.1 (172.16.1.1)Related Commands
ip split-horizon (RIP)
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.
ip split-horizon
no ip split-horizon
Syntax Description
This command has no arguments or keywords.
Defaults
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
Note
Note
Examples
The following simple example disables split horizon on a serial link. The serial link is connected to an X.25 network.
interface serial 0encapsulation x25no ip split-horizonRelated Commands
neighbor (RIP)
Defines a neighboring router with which to exchange routing information.
ip summary-address rip
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.
ip summary-address rip ip-address ip-network-mask
no 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.
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.
Examples
In the following example the major network 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 Ethernet interface 1 and 10.0.0.0 is not advertised.
Note
interface Ethernet1ip address 10.1.1.1 255.255.255.0ip summary-address rip 10.2.0.0 255.255.0exitrouter ripnetwork 10.0.0.0endRelated Commands
auto-summary (RIP)
Restores the default behavior of automatic summarization of subnet routes into network-level routes.
ip split-horizon (RIP)
Enables the split horizon mechanism.
neighbor (RIP)
To define a neighboring router with which to exchange routing information, use the neighbor command in router configuration mode. To remove an entry, use the no form of this command.
neighbor ip-address
no neighbor ip-address
Syntax Description
Command Default
No neighboring routers are defined.
Command Modes
Router configuration
Command History
Usage Guidelines
This command permits the point-to-point (nonbroadcast) exchange of routing information. When it is 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 10.108.0.0 except Ethernet interface 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 ripnetwork 10.108.0.0passive-interface ethernet 1neighbor 10.108.20.4Related Commands
network (RIP)
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.
network ip-address
no network ip-address
Syntax Description
Defaults
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.
Examples
The following example defines RIP as the routing protocol to be used on all interfaces connected to networks 10.99.0.0 and 192.168.7.0:
router ripnetwork 10.99.0.0network 192.168.7.0Related Commands
offset-list (RIP)
To add an offset to incoming and outgoing metrics to routes learned via Routing Information Protocol (RIP), use the offset-list command in router configuration mode. To remove an offset list, use the no form of this command.
offset-list {access-list-number | access-list-name} {in | out} offset [interface-type interface-number]
no offset-list {access-list-number | access-list-name} {in | out} offset [interface-type interface-number]
Syntax Description
Defaults
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.
Examples
In the following example, the router applies an offset of 10 to the delay component of a router only to access list 21:
offset-list 21 out 10In the following example, the router applies an offset of 10 to routes learned from Ethernet interface 0:
offset-list 21 in 10 ethernet 0output-delay
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.
output-delay delay
no output-delay
Syntax Description
delay
Delay between packets in a multiple-packet RIP update (in milliseconds). The range is from 8 to 50. The default is 0.
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.
Examples
The following example sets the interpacket delay to 10 milliseconds:
router ripoutput-delay 10router rip
To configure the Routing Information Protocol (RIP) routing process, use the router rip command in global configuration mode. To turn off the RIP routing process, use the no form of this command.
router rip
no router rip
Syntax Description
This command has no arguments or keywords.
Command Default
No RIP routing process is defined.
Command Modes
Global configuration
Command History
Examples
The following example shows how to begin the RIP routing process:
router ripRelated Commands
service-module ip rip relay
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.
service-module ip rip relay
no service-module ip rip relay
Syntax Description
This command has no keywords or arguments.
Command Default
RIP relay is disabled.
Command Modes
Interface configuration (config-if)
Command History
12.4(15)XY
This command was introduced.
12.4(20)T
This command was integrated into Cisco IOS Release 12.4(20)T.
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.
Examples
The following example enables RIP relay on an Integrated Services Router (ISR) cable modem. A static IP address is configured for the cable modem interface, and RIP relay is enabled on the interface. To allow RIP updates from unknown sources, the normal validation of the source IP address of incoming RIP routing updates is disabled. RIP is defined as the routing protocol to be used on all interfaces that are connected to networks 10.0.0.0 and 172.20.0.0.
interface Cable-Modem0/3/0ip address 10.5.5.5 255.255.255.0service-module ip rip relayexitrouter ripversion 2no validate-update-sourcenetwork 10.0.0.0network 172.18.0.0Related Commands
show ip rip database
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.
show ip rip database [ip-address mask]
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.
Examples
The following output shows a summary address entry for route 10.11.0.0/16, with three child routes active:
Router# show ip rip database10.0.0.0/8 auto-summary10.11.11.0/24 directly connected, Ethernet210.1.0.0/8 auto-summary10.11.0.0/16 int-summary^^^^^^^^^^^^^^^^^^^^^^^^^^^10.11.10.0/24 directly connected, Ethernet310.11.11.0/24 directly connected, Ethernet410.11.12.0/24 directly connected, Ethernet5The following is sample output from the show ip rip database command with a prefix and mask:
Router# show ip rip database 172.19.86.0 255.255.255.0172.19.86.0/24[1] via 172.19.67.38, 00:00:25, Serial0[2] via 172.19.70.36, 00:00:14, Serial1Table 135 describes the fields in the display.
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