Routing Information Protocol Setup in pfSense

Routing Information Protocol Explained

Routing Information Protocol

Enabling Routing Information Protocol (RIP) in pfSense.

The Routing Information Protocol (RIP) is one of the oldest distance-vector routing protocol, which employs the hop count as a routing metric. RIP prevents routing loops by implementing a limit on the number of hops allowed in a path from the source to a destination. The maximum number of hops (one portion of the path between source and destination; each time packets are passed to the next device, a hop occurs) allowed for the protocol is 15. This limit, however, also limits the size of networks that RIP can support (a hop count of 16 is considered unreachable).

RIP implements several algorithms to ensure incorrect routing information from being propagated. As a result, it is considered relatively stable. Using RIP, a gateway host sends its entire routing table, which lists all the other hosts it knows about, to its closest neighbor host every 30 seconds. The neighbor host in turn will pass the information on to its next neighbor and so on until all hosts within the network have the same knowledge of routing paths, a state known as network convergence. As networks increased in size, it became evident there could be a massive traffic burst every 30 seconds, even if the routers had been initialized at random times.


RIP uses the User Datagram Protocol (UDP) as its transport protocol, and is assigned the reserved port number 520. The original specification of RIP was defined in RFC 1058 and uses classful routing. The periodic routing updates do not carry subnet information and lack support for variable length subnet masks, making it impossible to have different-sized subnets inside the same network class. RIP version 2 was developed in 1993 and last standardized in 1998. It included the ability to carry subnet information and also multicasts the routing table (to 222.0.0.9) instead of broadcasting the table, to avoid unnecessary load on hosts that do not participate in routing. It is defined in RFC 2453. To maintain compatibility with version 1, the maximum number of hops is still 15. RIPng, defined in RFC 2080, incorporates several improvements over version 2, including support for IPv6 networking, attaching arbitrary tags to routes, and sending updates on UDP port 521. pfSense does not seem to currently support RIPng.

The major alternative to RIP is the Open Shortest Path First Protocol, which was discussed in a previous blog posting. Other alternatives include Cisco’s proprietary Interior Gateway Routing Protocol (IGRP), a distance-vector routing protocol, and its replacement, Enhanced Interior Gateway Routing Protocol (EIGRP).

Enabling Routing Information Protocol in pfSense

To enable RIP in pfSense, first navigate to Services -> RIP. At “Enable RIP”, check the check box. At “Interfaces”, select at least one interface (hold CTRL down while clicking to select multiple interfaces). At “RIP Version”, select either RIP Version 1 or Version 2. At “Password”, set a password if using RIP version 2. Finally, press the “Save” button to save the changes.


External Links:

Routing Information Protocol at Wikipedia

Routing Information Protocol (RIP) at doc.pfsense.org

Routing Information Protocol (RIP)”>Routing Information Protocol at SearchNetworking

Introduction to Routing Information Protocol (RIP) on YouTube

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