Your Complete Guide to Routing Information Protocol (RIP)
In 1981, the Routing Information Protocol (RIP) was first developed as GWINFO in the Xerox Network Systems (XNS) protocol suite for the Xerox PARC Universal Protocol. RIP, which was first described in RFC 1058 in 1988, has a reputation for being simple to set up and use on small networks.
It is an Interior Gateway Protocol (IGP) designed to distribute routing information within an Autonomous System (AS).
Routing Information Protocol
RIP is a dynamic routing protocol that stands for Routing Information Protocol, it uses hop count as a routing metric to find the best route between a source network and a destination network. It is a distance-vector routing protocol that operates at the Network layer of the OSI model and has an AD value of 120. The 520 port is used by RIP.
How does Routing Information Protocol work?
In order to choose which path to place a packet on to reach its destination, RIP uses a distance vector method. A routing table, or a list of all the locations the router is capable of reaching, is kept by each RIP router. Every 30 seconds, each router broadcasts its whole routing table to the closest neighbours.
The other routers to which a router is directly connected in this sense are the other routers that are on the same network segments as the chosen router. Up until all RIP hosts inside the network are aware of the same routing paths, the neighbours send the information on to their closest neighbours in turn. This shared knowledge is called convergence.
A router will update its table entry with the length and next-hop address of the shorter path if it receives an update on a route and the new path is shorter. If the new path is longer, it will wait for a "hold-down" period to check if subsequent updates also include the longer path. If the new, lengthier path is found to be stable, it will just update the table entry.
The network learns about a router crash or broken network connection when the affected router stops delivering updates to its neighbours or ceases sending and receiving updates across the broken connection. A RIP router will remove a particular route and notify the rest of the network of the issue through its own periodic updates if the routing database for that route isn't updated six times in a row (or for 180 seconds).
Features of Routing Information Protocol:
Here are some features of the Routing Information Protocol:
1. The network exchanges updates on a regular basis.
2. Routing information updates are sent continuously.
3. Updates include full routing tables.
4. Routers always trust routing data obtained from neighbor routers. It's also referred to as "routing on rumors."
Routing Information Protocol Versions
There are three versions of RIP – RIPv1, RIPv2, and RIPng. Let's discuss each one by one.
Routing Information Protocol Version 1 (RIPv1):
RIPv1 was standardized in 1988 and is known as Classful routing protocol as it does not send subnet mask information in the routing updates it sends.
Routing Information Protocol Version 2 (RIPv2):
RIPv2 was standardized in 1998 and is known as Classless routing protocol as it does send subnet mask information in the routing updates it sends.
Routing Information Protocol Next Generation (RIPng):
RIPng is the advanced version of RIPv2 that was made for IPv6. It is designed to provide routing functionalities for an IPv6-based network.
|Updates are sent as Broadcast||Updates are sent as Multicast||Updates are sent as Multicast|
|Broadcast at 255.255.255.255||Multicast at 22.214.171.124||Multicast at FF02::9|
|Authentication is not supported||It supports Authentication||Does not support authentication by itself.|
Classful Routing Protocol doesn't send information on subnet mask in its routing updates, whereas on the other hand, Classless Routing Protocol sends information on subnet mask in its routing updates.
Let's learn a little more about the metric of RIP -
Hop Count is the number of routers between the source and destination networks. The routing table includes the path that has the lowest hops since it is considered to be the best way to connect to a network. By limiting the number of hops permitted between a source and a destination, RIP avoids routing loops. A maximum of 15 hops are allowed in RIP.
Let's try to configure a small lab by advertising the Networks using:
Consider the 3-router topology shown above (PyNet1, PyNet2, PyNet3). PyNet1 's IP addresses are 192.168.1.1/24 on fa0/0 and 126.96.36.199/30 on fa0/1. PyNet2's IP addresses are 188.8.131.52/30 on fa0/0 and 184.108.40.206/30 on fa0/0. PyNet3 has the following IP addresses: 220.127.116.11/30 on fa0/0, 192.168.2.1/24 on fa0/1.
Configure RIP for PyNet1:
R1(config)# router rip
R1(config-router)# network 192.168.1.0
R1(config-router)# network 18.104.22.168
R1(config-router)# version 2
R1(config-router)# no auto-summary
Configuring RIP for PyNet2:
R2(config)# router rip
R2(config-router)# network 22.214.171.124
R2(config-router)# network 126.96.36.199
R2(config-router)# version 2
R2(config-router)# no auto-summary
Similarly, Configure RIP for PyNet3:
R3(config)# router rip
R3(config-router)# network 188.8.131.52
R3(config-router)# network 192.168.2.0
R3(config-router)# version 2
R3(config-router)# no auto-summary
Note: There is no auto-summarisation command that disables the auto-summarisation.
Timers in RIP aid in controlling performance. There are 4 types of timers related to RIP.
- Update timer: The routers using RIP typically communicate routing information every 30 seconds by default. The routers periodically swap over their routing tables using an Update timer.
- Invalid timer: When 180 seconds have passed without an update, the destination router deems it invalid. The destination router's mark hop counts as 16 for that router in this instance.
- Hold down timer: The router waits for a neighbouring router to respond during this period. The router is deemed dead if it is unable to reply within a predetermined period of time, which is 180 seconds by default.
- Flush time: If a route doesn't respond in the flush time, its entry will be flushed. It is 60 seconds by default.
Benefits of RIP
- Easy to configure
- Less complexity
- Less CPU utilization
- Easy to understand
- It promotes load balancing
- It is loop-free
Now, the question is -
Why is RIP Dead?
- It is only based on hop count. So, if there is a better route available with better bandwidth, it will not select that route.
- RIP uses a lot of bandwidth because it sends updates every 30 seconds.
- Only 15 hop counts are supported by RIP; hence a maximum of 16 routers can be specified.
- The convergence rate of RIP is very low, which means if a link goes down, it will take a lot of time to find an alternate route.
These are a few reasons why we prefer using other Routing Protocols like EIGRP and OSPF instead of Routing Information Protocol. So, GOODBYE to RIP!!
Routing Information Protocol (RIP) is outdated and is not mostly used. There are other protocols that replaced it, and you can learn about all these advanced protocols in our CCNA training. Please share your valuable feedback in the comment box below to let us know how you liked this article.
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