Routing Technology

Routing technology mainly refers to the routing selection algorithm. Internet routing protocol characteristics and classification. The routing algorithm can be divided into static routing algorithm and dynamic routing algorithm. Internet routing protocol features are: belongs to the adaptive selection protocol (i.e., dynamic) ; is a distributed routing protocol ; by adopting the hierarchical routing protocol, namely autonomous system autonomous system internal and external routing protocol. Internet routing protocol is divided into two major categories : Interior Gateway Protocol ( IGP protocol specific RIP and OSPF ) and the Exterior Gateway Protocol (EGP, use at present most is BGP).

Routing selection algorithm for classification

The routing algorithm is routing methods or strategies.

According to the routing algorithm can vary with the topology of the network or communication quantity adaptively adjust classification, routing algorithm can be divided into static routing algorithm and dynamic routing algorithm.

In 1, a static routing algorithm

Static routing algorithm is an adaptive routing algorithm, this is not a measurement, not only use the network state information according to certain fixed rules of decision simple routing algorithm. Static routing algorithm is characterized by simplicity and low cost, but can not adapt to the change of network state. Static routing algorithm including diffusion method and the fixed routing table method. A static route is to rely on manual input information to configure the routing table method.

Static route has the following advantages: reducing the router overheads. In a small Internet easily configured. Can control the routing updates. However, static routing in the network changes frequently occur in an environment does not work well. In large and frequent changes to the Internet, static route configuration is not reality.

2, dynamic routing algorithm

Dynamic routing algorithm is adaptive routing algorithm, is relying on the current network status information for decision-making, thereby allowing the routing results in a certain extent adapted to network topology structure and communication volume changes.

Dynamic routing algorithm is characteristic of can better adapt to the change of network state, but the implementation is more complex, the overhead is relatively large. Dynamic routing algorithm is commonly used routing table method, including the distributed routing algorithm and centralized routing algorithm. Distributed routing algorithm is each node through regular and the adjacent nodes to exchange routing state information to modify their routing table, so that the entire network routing is usually in a dynamic state of change. Centralized routing algorithm in the network is set up a specialized collection of nodes, each node periodically transmits state information, and then by the node according to network state information, dynamic calculation of every node in the routing table, and then a new routing table is sent to all nodes.

Routing protocol classification

Dynamic routing is a routing protocol can be generated automatically according to the actual situation of the routing table. Dynamic route is the main advantage to the destination site, if there are several paths, running a routing protocol (such as RIP or IGRP), and the ongoing data transfer path had interrupted, the router can automatically choose another path to transmit data. The establishment of a large network is an advantage. Most routing protocols can be classified into two basic routing protocol :

1, distance vector routing protocol

Computing network link distance vector, then according to the calculated results for routing. The typical distance vector routing protocol with IGRP and RIP. Router periodically to neighbor routers send a message, the content of the message is to own the entire routing table, such as: 1, reach the destination network over the distance, 2, arrived at the destination network next hop address running distance vector router according to neighboring routers send information, change their routing tables.

2, link state routing protocol

A typical link state routing protocol such as OSPF. Link state routing protocol is designed to get the entire network topology. Operation of link state routing protocols each router to provide the link state topology information, information content includes: 1, the router connected network link. In 2, as well as the link physical state. According to the returned information router based on the network topology changes modify the routing configuration, to adapt to the new routing.