A Brief Introduction to RIP V2

The use of the RIP Protocol can be traced back to a very early time. Have you mastered some old protocols? Now we will mainly introduce some features of the RIP V2 protocol. It only adds some extension features based on the r12001 protocol to apply to the routing selection environment of modern networks? These extensions include:

◆ Each route entry carries its own subnet mask

◆ Route selection and update are more authenticated

◆ Each route entry carries the next hop address

◆ External route mark

◆ Multicast route update

The most important thing is that the route update entry adds a subnet mask field, so the RIP Protocol can use a variable-length subnet mask, so that the RIP V2 protocol becomes a classless routing protocol?

How RIP V2 works

What is the broadcast method for v1? The RIP V2 protocol uses multicast to send update packets to other routers that declare RIP V2. The multicast address is the reserved D-class address 224.0.0.9.

The advantage of using multicast is that the RIP route connected to the local network selects irrelevant devices and no longer spends time parsing the update packets broadcast on the vro?

RIP V2 information frame format

Including: Command (8-bit), version (8-bit), unused (value: 0), address family identifier, route tag, IP address, subnet mask, next hop, and measurement value. Like r12001, can an update packet of the RIP V2 protocol contain up to 25 route entries? Similarly, UDP port 520 is used, and the maximum data packet size is 512 8-bit?

◆ COMMAND -- values: 1 and 2. 1 indicate request information, and 2 indicate Response Message.

◆ VERSION (VERSION) -- this field value is 2 for the RIP V2 protocol

◆ Address family indentifier (AFI) -- set IP to 2. this field is set to 0 when the message is a request to select the entire router (or host) route table.

◆ ROUTERTAG-provide this field to mark external routes or re-allocate routes to the RIP V2 protocol? By default, is this 16-bit field used to carry the autonomous system number of the route injected from the external route selection protocol to the RIP? Although the RIP Protocol does not use this field, the routing label field may be used to exchange route information through the RIP domain for external routes connected to a certain RIP domain in multiple locations? This field can also be used to organize external routes into a "group" to make it easier to control these routes in the RIP domain?

◆ Ip address: the destination ADDRESS of the route entry. Can it be the primary network ADDRESS? Subnet address or host route?

◆ Subnet mask (subnet mask) -- is a 32-bit MASK for the network and SUBNET of the IP address?

◆ Next hop -- if it exists, it identifies an address that is better than notifying the router? That is to say, the measurement value of the next hop address is closer to the destination than the advertised router on the same subnetwork? If this field is set to all 0 (0.0.0.0), is the IP address of the advertised router the best next hop address?

◆ Measurement (METRIC) -- is a 1 ~ Number of hops between 16?