RIP (Router Information Protocol) is a protocol that works with the distance vector algorithm and uses the Bellman-Ford algorithm to calculate routes. The RIP is located in the table of the routing devices as Administrative Distance 120. RIP routers only look at the number of devices (hop) it passes when choosing the best route. RIP accepts up to 15 hop. When this number is exceeded (i.e. when the 16th cap is) it returns the destination unreachable error.
RIP messages are sent encapsulated in the UDP (User Datagram Protocol) segment through the 520th port. Routers using RIP send the entire routing table to neighboring routers in 30 second cycles.
There are 3 different timers for RIP.
• Invalid: If the router using the RIP protocol does not receive an update for the network for 180 seconds (with metric 16), the forwarding is considered invalid.
• Flush: Deletes the routing information from the routing table if the router using RIP cannot receive information from the other router for 240 seconds.
• Holddown: One of the mechanisms used to prevent the loop in the routers. The waiting time is 180 seconds. Wait for the duration of the holddown timer for an inaccessible network. This update will not be accepted unless there is a routing update with a better metric than the old metric. As the network is thought to be converged after 180 seconds, the misrouting information will not come. For this reason, update information (even worse than the old metric) is accepted after the holddown timer expires.
The advantages of RIP:
• It is very useful in small networks.
• It is easy to use and apply.
• Since it does not know all the topology, it provides low memory consumption and low processor load on the router.
The disadvantages of RIP:
• RIP fails to scale on large and very large networks.
• RIP can go up to 15 hop. If the network is larger than 15 devices, the protocol returns an unreachable error.
• Making every router RIP announcements in a large network means that there is a lot of traffic on the internet and bandwidth is reduced.
• The recovery time of the RIP is long, which delays the re-editing of the changed topology and causes unwanted loops in the network. Due to these cycles, data cannot be accessed and delivered to the user.
RIP consists of 2 groups, version1 and version2. RIP version1 is a classfull protocol. Version1 is a protocol that does not send subnetmask (subnet mask) and works according to classes A, B, C, D. RIP version2 is a classless protocol and it also contains subnetmask in update information.
The RIP v1 configuration is done as follows:
Router> enable
Router # configure terminal
Router (config) #router rip
Router (config-router) #network <ip_address> (the network the router will report to other routers)
Configuration for RIP v2:
Router (config) #router rip
Router (config-router) #version 2
Router (config-router) #network <ip_address> <subnetmask> (the network the router will report to other routers)
Differences Between RIP Version1 (v1) and Version2 (v2):
RIP Version 1 (v1)
• v1 is classful routing.
• v1 does not carry subnetmask information in periodic updates. Therefore, RIP v1 does not work properly when subnetting is done on a network.
• v1 announces its periodic updates as broadcast.
• Authentication is not performed when using v1.
• v1 does not report the address of the next network device.
• v1 supports Fixed Length Subnet Mask (FLSM).
• v1 allows 6 load balancing. The default is 4.
• Supports "split horizon" and "split horizon with poison reverse".
RIP Version 2 (v2)
• v2 is a Classless protocol and is included in the Classless Inter-Domain Routing (CIDR) group.
• v2 carries subnetmask information in its periodic updates. Subnetting can be done on the network used.
• v2 announces its periodic updates as multicast (224.0.0.9).
• Authentication can be done while using v2. (Authentication is used to verify that the routes distributed across the network come from authorized sources.)
• v2 indicates the address of the next network device.
• v2 supports Variable Length Subnet Mask (VLSM).
• v2 supports manual routing summarization.
• A router with RIP v1 installed also accepts RIP V2 updates; but a router using RIP v2 only accepts v2 updates.
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