RIP stands for Routing Information Protocol. RIP is an intra-domain routing protocol used within an autonomous system. Here, intra-domain means routing the packets in a defined domain, for example, web browsing within an institutional area. To understand the RIP protocol, our main focus is to know the structure of the packet, how many fields it contains, and how these fields determine the routing table.
- Routing Information Protocol (RIP) is a true distance-vector routing protocol.
- It sends the complete routing table out to all active interfaces every 30 seconds
- RIP only uses hop count to determine the best way to a remote network
- It has a maximum allowable hop count of 15
- The administrative Distance is 120
- Bellman-ford algorithm
- Works well in small networks, but it’s inefficient on large networks
- RIP version 1 uses only Classful routing, which means that all devices in the network must use the same subnet mask
- RIP version 2 does send subnet mask information with the route updates. This is called classless routing.
Features of RIP
- Updates of the network are exchanged periodically.
- Updates (routing information) are always broadcast.
- Full routing tables are sent in updates.
- Routers always trust routing information received from neighbor routers. This is also known as Routing on rumors.
Versions of RIP:
- Rip V1
- RIP V2
Difference between RIP V1 and V2:
| PARAMETER | RIP v1 | RIP v2 |
|---|---|---|
| RFC | RFC 1058 | RFC 1721,1722 and 2453 |
| Routing | Classful | Classless |
| Routing update address | Broadcast (255.255.255.255) | Multicast (224.0.0.9) |
| Subnet mask | Does not send subnet mask information with routing update | Sends subnet mask information with routing update |
| VLSM | Not Supported | Supported |
| CIDR | Not Supported | Supported |
| Authentication | Not Supported | Supported |
| Discontiguous network | Not Supported | Supported |
How to Configure Routing Information Protocol
Enabling RIP and Configuring RIP Parameters
| Steps | Command or Action | Purpose |
|---|---|---|
| Step 1 | enableExample: Device# enable | Enables privileged EXEC mode. > Enter your password if prompted. |
| Step 2 | configure terminalExample: Device# configure terminal | Enters global configuration mode. |
| Step 3 | router ripExample: Device(config)# router rip | Enables a RIProuting process and enters the router configuration mode. |
| Step 4 | network ip-addressExample: Device(config-router)# network 10.1.1.0 | Associates a network with a RIP routing process. |
| Step 5 | neighbor ip-addressExample: Device(config-router)# neighbor 10.1.1.2 | Defines a neighboring device with which to exchange routing information. |
| Step 6 | auto-summaryExample: Device(config-router)# auto-summary | Restores the default behavior of automatic summarization of subnet routes into network-level routes. |
| Step 7 | offset-list [access-list-number |Example: Device(config-router)# offset-list 98 in 1 Ethernet 1/0 | (Optional) Applies an offset list to routing metrics |
| Step 8 | timers basic update invalid holddown flush [sleeptime]Example: Device(config-router)# timers basic 1 2 3 4 | (Optional) Adjusts routing protocol timers. |
| Step 9 | maximum-paths maximumExample: Device(config-router)# maximum-paths 16 | Configures the maximum number of equal-cost parallel routes that RIP will install into the routing table. |
| Step 10 | distance admin-distance [prefix prefix-lengthExample: Device(config-router)# distance 85 192.168.10.0/24 | Defines the administrative distance assigned to routes discovered by RIP. |
| Step 11 | endExample: Device(config-router)# end | Exits router configuration mode and returns to privileged EXEC mode. |
RIP timers:
- Update timer: The default timing for routing information being exchanged by the routers operating RIP is 30 seconds. Using an Update timer, the routers exchange their routing table periodically.
- Invalid timer: If no update comes until 180 seconds, then the destination router considers it invalid. In this scenario, the destination router mark hop counts as 16 for that router.
- Hold down timer: This is the time for which the router waits for a neighbor router to respond. If the router isn’t able to respond within a given time then it is declared dead. It is 180 seconds by default.
- Flush time: It is the time after which the entry of the route will be flushed if it doesn’t respond within the flush time. It is 60 seconds by default. This timer starts after the route has been declared invalid and after 60 seconds i.e time will be 180 + 60 = 240 seconds.