The main function of a router is to select paths. Maintained in the memory of the router with a path table, recorded logical address of each network, for identifying the other network.
In the Internet, when a router receives a packet transmitted from one network to another network, the packet is discarded outer interpret data packet, obtains a logical address of the destination network, the use of complex programs to decide information is sent via the most appropriate path which then repackaged and forwarded.
Further comprising filtering function of the router, store and forward, traffic management, media conversion. Some routers also have enhanced features encryption, data compression, priority, fault tolerance management.
Since the router works at the network layer bridge than it processes the information to be more, and thus the processing speed is slower than a bridge.
Typical routing in two ways: static routing and dynamic routing.
Static route is a fixed routing table is provided in the router. Unless administrator intervention, or static route will not change. Generally used for small-scale network, fixed network topology.
When the dynamic routing and static routing conflict, subject to a static route. Dynamic routing is mutual communication between routers in the network, routing information is transmitted, the process using a router table to update the routing information received.
It can adapt to changes in real-time network structure, if the routing update information indicates the occurrence of a change in the network, routing software will recalculate the route, and issued new routing updates.
This information through various networks, causing the router to restart its routing algorithm, and update their routing tables to reflect the network topology changes dynamically.
Dynamic routing network suitable for large-scale, complex network topology of the network.
Of course, a variety of dynamic routing protocol consumes network bandwidth and CPU resources to varying degrees. When routing a packet in a router, the router searches the static route, if found forwarding packets according to the corresponding static route; otherwise the dynamic routing lookup.
In a router, you can also configure one or more static routes and dynamic routing. They maintain their routing tables are provided to the forwarding process, but between these routing table entries may conflict.
This conflict can be resolved by configuring the priority of each routing table. Generally, static routes with the highest default priority, when other routing table entry with it not contradictory, are by static routing and forwarding.
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