RIP is a #classful #Distance Vector Routing Protocol that use hop count as metric to find out the routing path. The underlying #algorithm used is the Bellman-Ford Algorithm. If the metric of route is larger than 15, RIP will count it as unreachable. Routing updates are done via broadcast IP address. It can only run on IPv4 networks, in order to run IPv6 one needs to deploy RIPng (RIP next generation) instead. There is a classless implementation of RIP: RIP version 2 (RIPv2)#.
RIP will periodically broadcast the router’s routing table to its neighbours’ #port 520 every 30 seconds (default). The RIP message is transferred using #User Datagram Protocol (UDP). There are two types of message: request message and response message. Request message is sent out on startup by RIP enable interface which requests all RIP enabled neighbours to send routing table to it. Response message on the other hand is the response to the request message, which sends the data containing routing table to the requesting interface.
RIP only propagate the network address of known routes. There is no need to include subnet mask as part of the routing information since it could determine the subnet mask by just looking at the Address Classes default subnet masks. The boundary Router (the entry router to the RIP network) will summarise the RIP subnets from the internal network to the external network. This reduces the size of the Routing Table and resulted in a faster lookup in the routing table (single route can represent multiple routes). However, it comes at a cost of not able to support discontiguous network. Furthermore, if the subnet mask doesn’t match the class or a subnet of the class, RIP will not advertise the route to the other RIP enabled routers.
It could be enabled in #Cisco Internetwork Operating System (IOS) using the command router rip. To redistribute or advertising the routes in the routing table, we could run the command redistribute static.