routing protocols are designed to collect data on the network interconnection topology.The main task of routing, or, alternatively, selecting the most optimal route, usually solved by analysis of the particular tables which are placed in all end nodes and network routers.
order to automatically build the required table Routers vary with each other certain information with the help of specially designed service protocols, they are called "routing protocols".These include protocols NLSP, RIP, OSPF, which must be distinguished from the network, such as IP.
via the appropriate protocol routers gradually make networking card.Already on the basis of these data for each of the network numbers is decided which specific router to forward packets, which are sent to the network to the route in the end it turned out to be the most efficient.The results of the decisions taken are recorded in the routing table.When the network configuration change, some records will automatically become invalid.Then the packets are sent on false routes, can get lost or get stuck.On how quickly reports mashrutizatsii lead contents of the table to the actual state of the network directly affects the quality of the work itself.
routing protocols have several classifications.They can be both one-step and multi-step, static, dynamic, class, classless.Moreover, such protocols may be external and internal.In the one-step when choosing the most efficient route initially determined only by short-range router, but not all of their sequence.The static routes are entered manually by the network administrator.They are usually used in smaller networks that have simple and clear structure.Plus, of course, is the ease of setup, the absence of any loss of traffic for routing information and low resource requirements.But if there is a change in the network configuration, the routing table must be changed on all hosts manually.However, the increasing popularity are dynamic routing protocols.
Protocol BGP - one of the major routing protocols on the Internet.It is designed to exchange data on routes between large autonomous systems, so in addition to the standard information, carries the routes is on stand-alone systems.BGP protocol chooses the best route based on the rules that are adopted in the network, and does not use in their work the technical metrics.Also, this protocol uses a summation routes to reduce routing table.Currently it operates the fourth version of the protocol.
OSPF is also quite popular dynamic protocol.It is based on technology that monitors the status of the channel and uses for its work Dijkstra's algorithm.Its advantages include high speed convergence, the most efficient use of bandwidth and support of network masks of variable length.
RIP-protocol - one of the oldest, which, however, is quite common to this day.It is used in small networks with a simple structure.The protocol is simple to use and install.At the heart of his work are distance vector algorithms.If you use all the RIP routing table entries contain the address of a network or destination host.
Routing protocols are quite diverse, there are a large number of them, and each has both advantages and negative sides.
