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This chapter describes how to configure the Routing Information Protocol (RIP) on the Cisco NX-OS device.
This section includes the following topics:
RIP uses User Datagram Protocol (UDP) data packets to exchange routing information in small internetworks. RIPv2 supports IPv4. RIPv2 uses an optional authentication feature supported by the RIPv2 protocol (see the “RIPv2 Authentication” section).
RIP uses the following two message types:
RIP uses a hop count for the routing metric. The hop count is the number of routers that a packet can traverse before reaching its destination. A directly connected network has a metric of 1; an unreachable network has a metric of 16. This small range of metrics makes RIP an unsuitable routing protocol for large networks.
You can configure authentication on RIP messages to prevent unauthorized or invalid routing updates in your network. Cisco NX-OS supports a simple password or an MD5 authentication digest.
You can configure the RIP authentication per interface by using keychain management for the authentication keys. Keychain management allows you to control changes to the authentication keys used by an MD5 authentication digest or simple text password authentication. See the Cisco Nexus 9000 Series NX-OS Security Configuration Guide for more details about creating keychains.
To use an MD5 authentication digest, you configure a password that is shared at the local router and all remote RIP neighbors. Cisco NX-OS creates an MD5 one-way message digest based on the message itself and the encrypted password and sends this digest with the RIP message (Request or Response). The receiving RIP neighbor validates the digest by using the same encrypted password. If the message has not changed, the calculation is identical and the RIP message is considered valid.
An MD5 authentication digest also includes a sequence number with each RIP message to ensure that no message is replayed in the network.
You can use split horizon to ensure that RIP never advertises a route out of the interface where it was learned.
Split horizon is a method that controls the sending of RIP update and query packets. When you enable split horizon on an interface, Cisco NX-OS does not send update packets for destinations that were learned from this interface. Controlling update packets in this manner reduces the possibility of routing loops.
You can use split horizon with poison reverse to configure an interface to advertise routes learned by RIP as unreachable over the interface that learned the routes. Figure 11-1 shows a sample RIP network with split horizon and poison reverse enabled.
Figure 11-1 RIP with Split Horizon Poison Reverse
Router C learns about route X and advertises that route to Router B. Router B in turn advertises route X to Router A but sends a route X unreachable update back to Router C.
You can configure a route policy on a RIP-enabled interface to filter the RIP updates. Cisco NX-OS updates the route table with only those routes that the route policy allows.
You can configure multiple summary aggregate addresses for a specified interface. Route summarization simplifies route tables by replacing a number of more-specific addresses with an address that represents all the specific addresses. For example, you can replace 10.1.1.0/24, 10.1.2.0/24, and 10.1.3.0/24 with one summary address, 10.1.0.0/16.
If more specific routes are in the routing table, RIP advertises the summary address from the interface with a metric equal to the maximum metric of the more specific routes.
Note Cisco NX-OS does not support automatic route summarization.
You can use RIP to redistribute static routes or routes from other protocols. You must configure a route map with the redistribution to control which routes are passed into RIP. A route policy allows you to filter routes based on attributes such as the destination, origination protocol, route type, route tag, and so on. For more information, see Chapter15, “Configuring Route Policy Manager”
Whenever you redistribute routes into a RIP routing domain, Cisco NX-OS does not, by default, redistribute the default route into the RIP routing domain. You can generate a default route into RIP, which can be controlled by a route policy.
You also configure the default metric that is used for all imported routes into RIP.
You can use load balancing to allow a router to distribute traffic over all the router network ports that are the same distance from the destination address. Load balancing increases the usage of network segments and increases effective network bandwidth.
Cisco NX-OS supports the Equal Cost Multiple Path (ECMP) feature with up to 16 equal-cost paths in the RIP route table and the unicast RIB. You can configure RIP to load balance traffic across some or all of those paths.
Cisco NX-OS supports stateless restarts for RIP. After a reboot or supervisor switchover, Cisco NX-OS applies the running configuration and RIP immediately sends request packets to repopulate its routing table.
Cisco NX-OS supports multiple instances of the RIP protocol that run on the same system. RIP supports virtual routing and forwarding (VRF) instances.
The following table shows the licensing requirements for this feature:
RIP has the following prerequisites:
RIP has the following configuration guidelines and limitations:
Table 11-1 lists the default settings for RIP parameters.
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This section includes the following topics:
Note If you are familiar with the Cisco IOS CLI, be aware that the Cisco NX-OS commands for this feature might differ from the Cisco IOS commands that you would use.
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To disable the RIP feature and remove all associated configurations, use the following command in global configuration mode.
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Disables the RIP feature and removes all associated configurations. |
You can create a RIP instance and configure the address family for that instance.
You must enable RIP (see the “Enabling RIP” section).
3. address-family ipv4 unicast
4. (Optional) show ip rip [ instance instance-tag ] [ vrf vrf-name ]
To remove the RIP instance and the associated configurations, use the following command in global configuration mode.
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Note You must also remove any RIP commands configured in interface mode.
You can configure the following optional parameters for RIP in address-family configuration mode:
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Sets the administrative distance for RIP. The range is from 1 to 255. The default is 120. See the “Administrative Distance” section. |
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Configures the maximum number of equal-cost paths that RIP maintains in the route table. The range is from 1 to 64. The default is 16. |
This example shows how to create a RIP instance for IPv4 and set the number of equal-cost paths for load balancing:
switch(config)# router rip Enterprise
switch(config-router)# address-family ipv4 unicast
switch(config-router-af)# max-paths 10
switch(config-router-af)# copy running-config startup-config
You can restart a RIP instance. This clears all neighbors for the instance.
To restart an RIP instance and remove all associated neighbors, use the following command:
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You must enable RIP (see the “Enabling RIP” section).
2. interface interface-type slot/port
4. (Optional) show ip rip [ instance instance-tag ] interface [ interface-type slot/port ] [ vrf vrf-name ] [ detail ]
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interface interface-type slot/port |
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show ip rip [ instance instance-tag ] interface [ interface-type slot/port ] [ vrf vrf-name ] [ detail ] |
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This example shows how to add Ethernet 1/2 interface to a RIP instance:
switch(config)# interface ethernet 1/2
switch(config-if)# ip router rip Enterprise
switch(config)# copy running-config startup-config
You can configure authentication for RIP packets on an interface.
You must enable RIP (see the “Enabling RIP” section).
Configure a keychain if necessary before enabling authentication. See the Cisco Nexus 9000 Series NX-OS Security Configuration Guide for details on implementing keychains.
2. interface interface-type slot/port
3. ip rip authentication mode { text | md5 }
This example shows how to create a keychain and configure MD5 authentication on a RIP interface:
switch(config)# key chain RIPKey
switch(config-keychain)# key 2
switch(config-keychain-key)# accept-lifetime 00:00:00 Jan 01 2000 infinite
switch(config-keychain-key)# send-lifetime 00:00:00 Jan 01 2000 infinite
switch(config-keychain-key)# exit
switch(config)# interface ethernet 1/2
switch(config-if)# ip rip authentication mode md5
You can configure a RIP interface to receive routes but not send route updates by setting the interface to passive mode.
To configure a RIP interface in passive mode, use the following command in interface configuration mode:
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You can configure an interface to advertise routes learned by RIP as unreachable over the interface that learned the routes by enabling poison reverse.
To configure split horizon with poison reverse on an interface, use the following command in interface configuration mode:
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Enables split horizon with poison reverse. Split horizon with poison reverse is disabled by default. |
You can create aggregate addresses that are represented in the routing table by a summary address. Cisco NX-OS advertises the summary address metric that is the smallest metric of all the more-specific routes.
To configure a summary address on an interface, use the following command in interface configuration mode:
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You can configure RIP to accept routing information from another routing protocol and redistribute that information through the RIP network. Redistributed routes can optionally be assigned a default route.
You must enable RIP (see the “Enabling RIP” section).
Configure a route map before configuring redistribution. See the“Configuring Route Maps” section for details on configuring route maps.
3. address-family ipv4 unicast
4. redistribute { bgp as | direct | eigrp | isis | ospf | ospfv3 | rip } instance-tag | static } route-map map-name
5. (Optional) default-information originate [ always ] [ route-map map-name ]
6. (Optional) default-metric value
7. (Optional) show ip rip route [{ ip-prefix [ longer -prefixes | shorter-prefixes]] [ vrf vrf-name ] [ summary ]
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Creates a new RIP instance with the configured instance-tag. |
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redistribute { bgp as | direct |{ eigrp | isis | ospf | ospfv3 | rip } instance-tag | static } route-map map-name switch(config-router-af)# redistribute eigrp 201 route-map RIPmap |
Redistributes routes from other protocols into RIP. See the “Configuring Route Maps” section for more information about route maps. |
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default-information originate [ always ] [ route-map map-name ] switch(config-router-af)# default-information originate always |
(Optional) Generates a default route into RIP, optionally controlled by a route map. |
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(Optional) Sets the default metric for all redistributed routes. The range is from 1 to 15. The default is 1. |
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show ip rip route [ ip-prefix [ longer-prefixes | shorter-prefixes ] [ vrf vrf-name] [summary ] |
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copy running-config startup-config switch(config-router-af)# copy running-config startup-config |
This example shows how to redistribute EIGRP into RIP:
switch(config)# router rip Enterprise
switch(config-router)# address-family ipv4 unicast
switch(config-router-af)# redistribute eigrp 201 route-map RIPmap
switch(config-router-af)# copy running-config startup-config
You can configure Cisco NX-OS RIP to behave like Cisco IOS RIP in the way that routes are advertised and processed.
Directly connected routes are treated with cost 1 in Cisco NX-OS RIP and with cost 0 in Cisco IOS RIP. When routes are advertised in Cisco NX-OS RIP, the receiving device adds a minimum cost of +1 to all received routes and installs the routes in its routing table. In Cisco IOS RIP, this cost increment is done on the sending router, and the receiving router installs the routes without any modification. This difference in behavior can cause issues when both Cisco NX-OS and Cisco IOS devices are working together. You can prevent these compatibility issues by configuring Cisco NX-OS RIP to advertise and process routes like Cisco IOS RIP.
You must enable RIP (see the “Enabling RIP” section).
This example shows how to disable Cisco NX-OS RIP compatibility with Cisco IOS RIP by returning all direct routes from cost 0 to cost 1:
switch(config)# router rip 100
switch(config-router)# no metric direct 0
You can configure multiple RIP instances, create multiple VRFs, and use the same or multiple RIP instances in each VRF. You assign a RIP interface to a VRF.
Note Configure all other parameters for an interface after you configure the VRF for an interface. Configuring a VRF for an interface deletes all the configurations for that interface.
You must enable RIP (see the “Enabling RIP” section).
6. (Optional) address-family ipv4 unicast
7. (Optional) redistribute {bgp as | direct | {eigrp | isis | ospf | ospfv3 | rip} instance-tag | static} route-map map-name
8. interface ethernet slot/port
10. ip-address ip-prefix/length
11. ip router rip instance-tag
12. (Optional) show ip rip [ instance instance-tag ] interface [ interface-type slot/port ] [ vrf vrf-name ]
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Creates a new RIP instance with the configured instance tag. |
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(Optional) Configures the VRF address family for this RIP instance. |
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redistribute { bgp as | direct | { eigrp | isis | ospf | ospfv3 | rip } instance-tag | static } route-map map-name switch(config-router-vrf-af)# redistribute eigrp 201 route-map RIPmap |
(Optional) Redistributes routes from other protocols into RIP. See the “Configuring Route Maps” section for more information about route maps. |
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Configures an IP address for this interface. You must do this step after you assign this interface to a VRF. |
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show ip rip [ instance instance -tag ] interface [ interface-type slot/port ] [ vrf vrf-name ] |
(Optional) Displays RIP information for an interface in a VRF. |
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This example shows how to create a VRF and add an interface to the VRF:
switch(config)# vrf context RemoteOfficeVRF
switch(config)# router rip Enterprise
switch(config-router)# vrf RemoteOfficeVRF
switch(config-router-vrf)# address-family ipv4 unicast
switch(config-router-vrf-af)# redistribute eigrp 201 route-map RIPmap
switch(config-router-vrf-af)# interface ethernet 1/2
switch(config-if)# vrf member RemoteOfficeVRF
switch(config-if)# ip address 192.0.2.1/16
You can tune RIP to match your network requirements. RIP uses several timers that determine the frequency of routing updates, the length of time before a route becomes invalid, and other parameters. You can adjust these timers to tune routing protocol performance to better suit your internetwork needs.
Note You must configure the same values for the RIP timers on all RIP-enabled routers in your network.
You can use the following optional commands in address-family configuration mode to tune RIP:
You can use the following optional commands in interface configuration mode to tune RIP:
To display RIP configuration, perform one of the following tasks:
To display RIP statistics, use the following commands:
Use the clear ip rip policy statistics redistribute protocol process-tag command to clear policy statistics.
Use the clear ip rip statistics command to clear RIP statistics.
This example creates the Enterprise RIP instance in a VRF and adds Ethernet interface 1/2 to this RIP instance. The example also configures authentication for Ethernet interface 1/2 and redistributes EIGRP into this RIP domain.
redistribute eigrp 201 route-map RIPmap
ip rip authentication mode md5
See Chapter 15, “Configuring Route Policy Manager” for more information on route maps.