Its definition can be found in RFC1058, which uses UDP as the protocol carrier (i.e. the upper layer protocol UDP). We are most concerned about is RIP one of the segment, called the measure of segment, which is to hop as a counter (that is, the number of routes to walk to the counter) of paragraph (IP protocol and there was a TTL is not it). This measure segment will ultimately affect the establishment of the routing table. With reference to FIG:
Generally routed to undertake the following tasks:
1. rip send a request packet to each router known, given the requirements of other routers entire routing table. This message command field is 1, the address field is 0, a measure for the 16 lots (equivalent to infinity).
2. Accept the request, if the request is received earlier, put his complete routing table to the requester. If not, process IP requests entry, the entry in their own section add some hops, do not add the section 16. And then sent to the requester.
3. Accept the response. Update their routing tables. Use a small hop number of rules.
4. periodically update the routing table, typically 30s (often true) adjacent to the road once inspired its own routing table. This form allows broadcast form.
This agreement looks good job, but there is actually a lot of hidden suffering, such as RIP has no concept of subnets, such as loop dangerous. The upper limit of the number of hop and also limits the size of the network.