Cisco CCNA:Routing Information Protocol (RIP) v2 description

Routing Information Protocol (RIP) is a true distance-vector routing protocol. It sends the complete routing table out to all active interfaces every 30 seconds. RIP only uses hop count to determine the best way to a remote network, but it has a maximum allowable hop count of 15 by default, meaning that 16 is deemed unreachable. RIP works well in small networks, but it’s inefficient on large networks with slow WAN links or on networks with a large number of routers installed.
RIP version 1 uses only classful routing, which means that all devices in the network must use the same subnet mask. This is because RIP version 1 doesn’t send updates with subnet mask information in tow. RIP version 2 provides something called prefix routing, and does send subnet mask information with the route updates. This is called classless routing.

RIP version 2 (RIPv2)

RIP version 2 is mostly the same as RIP version 1. Both RIPv1 and RIPv2 are distance-vector protocols, which means that each router running RIP sends its complete routing tables out all active interfaces at periodic time intervals. Also, the timer and loop-avoidance schemes are the same in both RIP versions-i.e., holddown timers and split horizon rule. Both RIPv1 and RIPv2 are configured as classful addressing,(but RIPv2 is considered classless because subnet information is sent with each route update, ) and both have the same administrative distance(120).
But there are some important differences that make RIPv2 more scalable than RIPv1. And I’ve got to add a word of advice here before we move on; I’m definitely not advocating using RIP of either version in your network. But since RIP is an open standard, you can use RIP with any brand of router. You can also use OSPF, since OSPF is an open standard as well. RIP just requires too much bandwidth, making it pretty intensive to use in your network.
The following table shows the differences between RIPv1 and RIPv2:
RIPv1 RIPv2
Distance vector Distance vector
Maximum hop count of 15 Maximum hop count of 15
Classful Classless
No support for VLSM Supports VLSM network
No support for discontiguous network Supports discontiguous network
RIPv2, unlike RIPv1, is a classless routing protocol (even though it is configured as classful, like RIPv1), which means that it sends subnet mask information along with the route updates. By sending the subnet mask information with the updates, RIPv2 can support Variable Length Subnet Masks (VLSMs) as well as the summarization of network boundaries. In addition, RIPv2 can support discontiguous networking.

RIP Timers
RIP uses the following timers to regulate its performance:
Route update timer: sets the interval (typically 30 seconds) between periodic routing updates, in which the router sends a complete copy of its routing table out to all neighbors.
Route invalid timer: determines the length of time that must elapse(180 seconds) before a router determines that a route has become invalid. It will come to this conclusion if it hasn’t heard any updates about a particular route for that period. When that happens, the router will send out updates to all its neighbors letting them know that the route is invalid.
Holddown timer: sets the amount of time during which routing information is suppressed. Routes will enter into the holddown state when an update packet is received that indicated the route is unreachable. This continues until either an update packet is received with a better metric or until the holddown timer expires. The default is 180 seconds.
Route flush timer: sets the time between a route becoming invalid and its removal from the routing table (240 seconds). Before it’s removed from the table, the router notifies its neighbors of that route’s impending demise. The value of the route invalid timer must be less than that of the route flush timer. This gives the router enough time to tell its neighbors about the invalid route before the local routing table is updated.

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