Routing Information Protocol (RIP)

Routing Information Protocol (RIP) is a dynamic routing protocol that uses hop count as a routing metric to find the best path between the source and the destination network. It is a distance-vector routing protocol that has an AD value of 120 and works on the Network layer of the OSI model. RIP uses port number 520.

Hop Count

Hop count is the number of routers occurring in between the source and destination network. The path with the lowest hop count is considered as the best route to reach a network and therefore placed in the routing table. RIP prevents routing loops by limiting the number of hops allowed in a path from source and destination. The maximum hop count allowed for RIP is 15 and a hop count of 16 is considered as network unreachable.

Features of RIP

1. Updates of the network are exchanged periodically.
2. Updates (routing information) are always broadcast.
3. Full routing tables are sent in updates.
4. Routers always trust routing information received from neighbor routers. This is also known as Routing on rumors.

RIP versions:

There are three versions of routing information protocol – RIP Version1, RIP Version2, and RIPng.

RIP v1 is known as Classful Routing Protocol because it doesn’t send information of subnet mask in its routing update.
RIP v2 is known as Classless Routing Protocol because it sends information of subnet mask in its routing update.

>> Use debug command to get the details :

# debug ip rip

>> Use this command to show all routes configured in router, say for router R1 :

R1# show ip route

>> Use this command to show all protocols configured in router, say for router R1 :

R1# show ip protocols

Configuration :

Consider the above-given topology which has 3-routers R1, R2, R3. R1 has IP address 172.16.10.6/30 on s0/0/1, 192.168.20.1/24 on fa0/0. R2 has IP address 172.16.10.2/30 on s0/0/0, 192.168.10.1/24 on fa0/0. R3 has IP address 172.16.10.5/30 on s0/1, 172.16.10.1/30 on s0/0, 10.10.10.1/24 on fa0/0.

Configure RIP for R1 :

R1(config)# router rip R1(config-router)# network 192.168.20.0 R1(config-router)# network 172.16.10.4 R1(config-router)# version 2 R1(config-router)# no auto-summary

Note: no auto-summary command disables the auto-summarisation. If we don’t select any auto-summary, then the subnet mask will be considered as classful in Version 1.

Configuring RIP for R2:

R2(config)# router rip R2(config-router)# network 192.168.10.0 R2(config-router)# network 172.16.10.0 R2(config-router)# version 2 R2(config-router)# no auto-summary

Similarly, Configure RIP for R3 :

R3(config)# router rip R3(config-router)# network 10.10.10.0 R3(config-router)# network 172.16.10.4 R3(config-router)# network 172.16.10.0 R3(config-router)# version 2 R3(config-router)# no auto-summary

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.

Note that all these times are adjustable. Use this command to change the timers :

R1(config-router)# timers basic R1(config-router)# timers basic 20 80 80 90

Normal utilization of RIP:

1. Small to medium-sized networks: RIP is normally utilized in little to medium-sized networks that have moderately basic directing prerequisites. It is not difficult to design and requires little support, which goes with it a famous decision for little organizations.
2. Legacy organizations: RIP is as yet utilized in some heritage networks that were set up before further developed steering conventions were created. These organizations may not merit the expense and exertion of overhauling, so they keep on involving RIP as their directing convention.
3. Lab conditions: RIP is much of the time utilized in lab conditions for testing and learning purposes. A basic convention is not difficult to set up, which pursues it a decent decision for instructive purposes.
4. Backup or repetitive steering: In certain organizations, RIP might be utilized as a reinforcement or excess directing convention, on the off chance that the essential steering convention falls flat or encounters issues. RIP isn’t generally so productive as other directing conventions, however, it very well may be helpful as a reinforcement if there should be an occurrence of crisis.

Advantages of RIP :

• Simplicity: RIP is a relatively simple protocol to configure and manage, making it an ideal choice for small to medium-sized networks with limited resources.
• Easy implementation: RIP is easy to implement, as it does not require much technical expertise to set up and maintain.
• Convergence: RIP is known for its fast convergence time, meaning that it can quickly adapt to changes in network topology and route packets efficiently.
• Automatic updates: RIP automatically updates routing tables at regular intervals, ensuring that the most up-to-date information is being used to route packets.
• Low bandwidth overhead: RIP uses a relatively low amount of bandwidth to exchange routing information, making it an ideal choice for networks with limited bandwidth.
• Compatibility: RIP is compatible with many different types of routers and network devices, making it easy to integrate into existing networks.

Disadvantages of RIP :

• Limited scalability: RIP has limited scalability, and it may not be the best choice for larger networks with complex topologies. RIP can only support up to 15 hops, which may not be sufficient for larger networks.
• Slow convergence: While RIP is known for its fast convergence time, it can be slower to converge than other routing protocols. This can lead to delays and inefficiencies in network performance.
• Routing loops: RIP can sometimes create routing loops, which can cause network congestion and reduce overall network performance.
• Limited support for load balancing: RIP does not support sophisticated load balancing, which can result in suboptimal routing paths and uneven network traffic distribution.
• Security vulnerabilities: RIP does not provide any native security features, making it vulnerable to attacks such as spoofing and tampering.
• Inefficient use of bandwidth: RIP uses a lot of bandwidth for periodic updates, which can be inefficient in networks with limited bandwidth.