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Routing Information Protocol (RIP)1. RIP is a distance vector routing protocol that uses hop count as its metric. 39912
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2. RIP has two versions: RIP Version 1 (RIP-1), defined by RFC 1058, and RIP Version 2 (RIP-2), defined by RFC 2453. RIP-1 is the default version of RIP.
3. RIP-1 uses broadcasts to send routing information out on all defined network inter- faces. RIP-2 uses multicasts to send out routing advertisements on all defined net- works.
4. RIP-1 is classful and does not support variable length subnet masks (VLSM). RIP-2 is classless and supports VLSM.
5. The maximum hop count for either version is 15 hops. A route with a hop count of 16 is considered unreachable.
6. When redistributing, a default metric must be defined, or 15 will be used as the default, and any redistributed route will be inaccessible.
7. RIP advertises a full routing table every 30 seconds. Routes are marked as unusable if no updates are received in 180 seconds. Routes are removed if no update occurs after 240 seconds.
Note RIP uses UDP port 520 to communicate. RIP-1 broadcasts out the defined broadcast address for participating interfaces (the default defined address is 255.255.255.255). RIP-2 sends out multicast to the well-known address 224.0.0.9 on participating interfaces. If a neigh- bor is defined, Versions 1 and 2 send out as a unicast message to the neighbor address.
Configuration
1. Enable the RIP routing process:
(global) router rip
This command enables the RIP process and places the device in router configuration mode. If no networks are assigned to the process, RIP does not function.
2. Associate the network with the RIP process:
(router) network network-number
The network command associates the classful networks to be advertised with the routing process. If a subnet is entered, it is reduced to the major class address in the configuration. Therefore, any interface on the router that has an address assigned to the major class network becomes an active RIP interface unless configured otherwise.
3. (Optional) Specify the version of RIP that is used:
(router) version { 1 | 2 }
This configures the router to send and receive only the specified version of RIP pack- ets.
Note By default, when the RIP protocol is enabled, the router sends Version 1 packets but receives and processes both RIP-1 and RIP-2 packets. When you use the version command, the router sends and receives only the specified version. This behavior can be changed on a per-interface basis, as described in Steps 4 and 5.
4. (Optional) Change the RIP send parameters for a given interface:
(interface) ip rip send version [ 1 | 2 | 1 2]
In interface configuration mode, the router can be configured to send only Version 1 updates with the 1 option, only Version 2 updates with the 2 option, or both Version
1 and Version 2 updates with the 1 2 option. This command overrides both the default behavior and the global behavior assigned with the router version command.
5. (Optional) Change the RIP receive parameters for a given interface:
(interface) ip rip receive version [ 1 | 2 | 1 2]
In interface configuration mode, the router can be configured to receive only Version 1 updates with the 1 option, only Version 2 updates with the 2 option, or both Version 1 and Version 2 updates with the 1 2 option. This command overrides both the default behavior and the global behavior assigned with the router version command.