The Routing Information Protocol (RIP), one of the earliest routing protocols, is used by routers in a limited geographic area to determine routes to other networks inside an internet network. While it might not be as ubiquitous as some newer protocols due to certain limitations, understanding RIP is essential for any network professional. This is especially true for those pursuing Cisco certifications. This article offers a concise guide on configuring RIP on Cisco routers, ensuring your foundational knowledge is solid.

Understanding Routing Information Protocol (RIP):

The first protocol used for dynamic routing is the Routing Information Protocol (RIP). Although contemporary networks do not use it, using in small networks due to its clarity and settings as a starting point for understanding how the routing process operates. It is the reason Cisco has it on the CCNA test.

RIP is a routing protocol for distance vectors. Since every routing system employs a statistic, RIP uses the hop count. The RIP maximum hop count is 15 (CCNA test question). A route gets deemed inaccessible if there are more than 15 hops on it.

By default, routing updates get transmitted every 30 seconds. The source and destination port numbers are set to 520 when transmitted as UDP packets. There can only be 25 routes broadcast in a single packet since the maximum datagram size is only 504 bytes. The router will send more packets if there are more routes available.

RIP uses just two different message kinds. Responses and requests messages. As far as possible, the names are descriptive. A Request message gets sent when a RIP-enabled router interface starts up.

The newly received routes are added to the routing database of the first router as soon as it gets the Response messages. If the router receives a new route with a higher hop count but already has one in its database. The old route gets replaced. The router then communicates its routing table to its neighbors after that.

RIP Routing Updates:

Routing Information Protocol (RIP) messages are sent at regular intervals and when the network topology changes. The routing table of a device is updated to reflect the new route when it gets an RIP routing update that includes modifications to an entry. The path's metric value is raised by 1, and the sender gets identified as the following hop. Only the best route to a destination gets maintained by RIP devices. The device instantly starts communicating RIP routing updates to other network devices after changing its routing database to notify them of the change. These updates are provided separately from the RIP devices' regularly scheduled updates.

RIP Routing Metric:

The distance between the source and destination networks is calculated by the Routing Information Protocol (RIP) using a single routing metric. A hop-count value, usually 1 is assigned to each hop in a path from the source to the destination. When a device gets a routing update with a new or modified entry for a destination network, it updates the network's entry in the routing table by adding 1 to the metric value specified in the update. The sender's IP address gets utilized as the following hop. An interface network won't get advertised in any RIP update if it is undefined in the routing table.

Versions of RIP:

RIP Version 1 (RIPv1) refers to the original Routing Information Protocol (RIP). Classful routing gets used in the RFC 1058-described RIP standard. Due to the lack of subnet information in periodic routing updates, variable-length subnet masks (VLSM) were not supported. A network class must include only identically sized subnets. It is unfeasible to have subnets of different sizes inside the same network class since RIP, as per RFC 1058, does not enable VLSM. RIP is prone to assaults because of this restriction.

RIP Version 2 (RIPv2), discussed in RFC 2453, was created to address the shortcomings of the original RIP standard. Classless interdomain routing (CIDR) gets supported by RIPv2 since it can convey subnet information.

Verification in RIP:

The Routing Information Protocol (RIP) Version 2 (RIPv2) implementation by Cisco includes classless interdomain routing (CIDR), variable-length subnet masks (VLSMs), route summarization, and key management.

By default, the program only sends RIPv1 packets while receiving RIPv1 and RIPv2 packets. You may set up the program to only accept and send RIPv1 packets. A different option is to set the program to accept and send RIPv2 packets. You can specify the RIP version that an interface communicates to override the default behavior.

There is no authentication functionality in RIPv1. You can activate RIP authentication on an interface if you send and receive RIP v2 packets. Which keys may get utilized on the interface depends on the vital chain. Only when a key chain gets set up on that interface does authentication, including default authentication.

On an interface with RIP enabled Cisco provides two forms of authentication: plain-text authentication and message digest algorithm 5 (MD5) authentication. In every RIPv2 packet, plain-text authentication is used by default.

Exchange of Routing Information:

Routing Information Protocol (RIP) is a broadcast protocol RIP routing updates to reach non-broadcast networks must configure the Cisco software to allow this exchange of routing information.

By defining the passive-interface router configuration command, you may stop routing updates from being sent on a given set of interfaces to regulate the interfaces you wish to share routing updates.

The incoming and outgoing metrics to routes discovered by RIP can get increased by using an offset list. With an access list or an interface, you may opportunistically restrict the offset list. The performance of the routing protocol may be tuned using these timings to meet your internetwork requirements. The following timing modifications are available:

• The frequency (number of changes per second) of routing updates
• The period in seconds after which a route is deemed ineffective
• The time in seconds that routing information concerning preferable routes gets omitted.
• The number of seconds that need to elapse before a route gets purged from the routing table
• The frame for which routing changes will get delayed

Enable faster convergence of different IP routing algorithms and hence induce speedier fallback to redundant devices can modify the IP routing support in the Cisco software. In circumstances where rapid recovery is required, the overall objective is to minimize network interruptions for end users.