The Routing Information Protocol (RIP) is a distance-vector,interior gateway (IGP) routing protocol used by routers to exchange routing information.RIP uses 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 allowed for RIP is 15. This hop limit, however, also limits the size of networks that RIP can support.RIP version 2 (RIPv2) was developed due to the deficiencies of the original RIP.
Difference between RIPv1 and RIPv2:
RIPv2 is actually an enhancement of RIPv1's features and extensions raether than an entirely new protocol.
1) RIPv1 is Classful routing protocol and RIPv2 Classless routing protocol.
2) In RIPv1, subnet masks are NOT included in the routing update and In RIPv2 Subnet masks are included in the routing update.
3) RIPv2 multicasts the entire routing table to all adjacent routers at the address 126.96.36.199, as opposed to RIPv1 which uses broadcast (255.255.255.255). Unicast addressing is still allowed for special applications.
Cisco IOS, uses "router rip" command to enable RIP routing protocol. The version command is used to specify which RIP version to use (either 1 or 2). If the version command is omitted then the router defaults to sending RIPv1 but can receive both RIPv1 and RIPv2.
The "network" command is used to specify the directly connected subnets on the router to be configured and that are intended to be included in the routing updates.
According to the classful, network specified, the subnets of that network are automatically identified and participate in the routing update. By default routing updates are summarized at network boundaries.
In RIPv2 this auto summarization behavior can be turned off using the "no auto-summary" command. Moreover, manual summarization can be configured on a per interface level.
R1#show ip protocol
Routing Protocol is "rip"
Sending updates every 30 seconds, next due in 27 seconds
Invalid after 180 seconds, hold down 180, flushed after 240
Outgoing update filter list for all interfaces is not set
Incoming update filter list for all interfaces is not set
Default version control: send version 2, receive version 2
Interface Send Recv Triggered RIP Key-chain
FastEthernet0 2 2
FastEthernet1 2 2
Loopback0 2 2
Vlan1 2 2
Automatic network summarization is in effect
Maximum path: 4
Routing for Networks:
Routing Information Sources:
Gateway Distance Last Update
192.168.11.2 120 00:00:09
Distance: (default is 120)