Definition of RIP: How it Works and Characteristics

RIP (Routing Information Protocol) is a routing protocol used to exchange routing information between dynamic routers on IP or IPX Protocol. Before we discuss the meaning of RIP and how it works, you must first understand, what is routing?

What is Routing?

Routing is a protocol used to get a route from one network to another. These routes are called routes and route information can be dynamically assigned to other routers or can be assigned statically to other routers.

An administrator chooses a dynamic routing protocol based on the state of the network topology. For example, what is the size of the network, the available bandwidth, the processing power in the router, the make and model of the router, and the protocols used in the network? Routing is the process by which a router forwards packets to the destination network. A router makes a decision based on the IP address the packet goes to.

All routers use the destination IP address to send packets. In order for the routing decision to be correct, the router must learn how to reach the destination. When a router uses dynamic routing, this information is learned from other routers. When using static routing, a network administrator manually configures information about the network to be routed.

If the routing used is static, then the configuration must be done manually, the network administrator must enter or delete static routes in case of topology changes. On a large-scale network, if you continue to use static routing, it will be a waste of time for network administrators to update the routing table. Therefore static routing is only possible for small-scale networks. While dynamic routing is usually implemented in large-scale networks and requires more capabilities from the administrator, one type of dynamic routing is RIP.

Definition of RIP

Routing Information Protocol (RIP) is a Routing Protocol that uses Distance Vector, therefore RIP uses the number of hops to determine the best way to a particular network address, but by default, RIP has a maximum number of hops, which is 15 hops. Therefore, the 16th Hop onwards will be considered Unreachable. Therefore, RIP can work well on small types of networks, but RIP is not efficient on large networks or on networks that have a large number of routers.

RIP for IPv4 is divided into 2 versions, namely RIPv1 & RIPv2. As for IPv6, you can use RIPng. RIPv1 sends a complete Routing Table to all active interfaces every 30 seconds. RIPv1 uses Classful Routing, which means RIPv1 does not support Subnetting. While RIPv2 already provides something called Prefix Routing, which contains SubnetMask information.

RIP History

The Routing Information Protocol (RIP) was designed in the 1980s for use with the Xerox Network Systems (XNS) protocol suite using the Bellman-Ford algorithm, which was first used in computer networks in 1968, as a precursor to the ARPANET routing algorithm.

RIP was also first defined in RFC 1058 (1988). This protocol has been developed several times, resulting in RIP Version 2 (RFC 2453). Both versions are still in use today, although they have been rendered technically obsolete by more advanced techniques, such as Open Shortest Path First (OSPF) and the OSI IS-IS protocol. RIP has also been adapted for use in IPv6 networks, known as the RIPng standard (RIP Next Generation / RIP next generation), published in RFC 2080 (1997).

RIP first became popular as a result of its inclusion in the 4.2 release of the Berkeley BSD UNIX platform. It is supported by Microsoft Windows NT Server and Microsoft Windows 2000 Server and has been adapted to AppleTalk network systems as the Routing Table Maintenance Protocol (RTMP).

How RIP Works

RIP is a distance-vector routing, which advertises routing information by sending routing updates out through the interface on the router. This update contains a series of information that represents a subnet and a metric.

The metric represents how good the route/path according to the router's perspective is, with the smaller the metric price the better the path. All routers that receive a copy of the distance vector routing update receive this information and may add some paths to their routing table.

The receiving router will add a new path about this subnet based on this routing update only if it doesn't have information about this route/path beforehand or it already knows this route but this new information turns out to have better route information (smaller metric).

In routing updates, if the subnet mask is not included in the information, it is called classful routing. Classful routing does not support VLSM (variable length subnet mask). RIP uses the number of hops as a measure. In simple terms, the RIP work process is as follows:

1. The host listens on the broadcast address if there is a routing update from the gateway.
2. The host will first check the local routing table if it receives a routing update.
3. By default, RIP updates data every 30 seconds.
4. If the route does not exist, the information is immediately entered into the routing table.
5. If the route already exists, the smallest metric will be taken as a reference.
6. Routes through a gateway will be deleted if there is no update from that gateway within a certain time
7. Especially for gateways, RIP will send routing updates to broadcast addresses on each connected network

RIP Characteristics

• Distance vector routing protocol
• Hop count as a metric for route selection
• Maximum hop count 15, 16th hop count is considered unreachable
• By default routing updates every 30 seconds
• RIPv1 (classful routing protocol) does not send subnet mask on updates
• RIPv2 (classless routing protocol) sends the subnet mask on update2. How Static Routing Works

Advantages and Disadvantages of RIP

RIP advantages:

• Using the Triggered Update method.
• RIP has a timer to know when the router should return routing information.
• If a change occurs on the network, while the timer has not expired, the router must still send routing information because it was triggered by the change (triggered update).
• Setting up routing using RIP is uncomplicated and gives quite acceptable results, especially if network link failures are rare.

Disadvantages of RIP:

• A limited number of hosts.
• RIP has no information about the subnets of each route.
• RIP does not support Variable Length Subnet Masking (VLSM).
• When the first run, it only knows how to route itself (local information) and doesn't know the network topology it is in

Conclusion

Routing Information Protocol (RIP) is a routing protocol that uses distance vector routing algorithms. RIP does not have a complete map of the existing network. RIP uses the hop count as a metric and the link with the smallest hop count will be the best link (best path).

Hopefully, this article about the Definition of RIP, How it Works and Characteristics, gives you a little insight. Also, read an article about Definitions, Functions, and Types of Network Protocols that you may need to know. Thank you.