The basic difference between Route and Bridge

Copyright@ July 2010, by antonio081014.

These days, I was working on a network security of Cloud Computing, so those used to confuse me a lot are finally configured out. One of them is the difference between route and hub.

A computer, which is just a node in the network, connecting to the Local Area Network(LAN). It has two addresses to identify the its identification. One is Media Access Control(MAC) address, which uniquely identifies each node in the network, and is stored on the network interface card(NIC) itself. Each NIC has a unique MAC address. It is the MAC address which will be used by the Ethernet protocol while creating frames to transfer data from and to a computer, physically. The other address is the famous IP address, which is generated in the network layer, it can be used by the applications.

For hub (bridge), it just retransmits the coming package to all the connected nodes (Broadcast), and then if the package's MAC address is not matchable with the destination's MAC's address, it will be dropped directly. These operations are run on the Ethernet layer and Physical layer.

For Route, it usually has a route table embedded in the router. The route table keep the record of a mapping, which is the map between an IP address and the port of the router. When a pkg coming, the router will check the route table to identify which port maps to the destination's IP. Then it sends the package through that port. The route table is dynamic updated, which means the router will keep sending arp to all of the nodes. Then all the nodes will send the ARP package back, which tell the router the information of each node : 1) The map of MAC address and the IP address, this will tell the node(Each node's MAC is identified) what IP address this node are using. 2) The map of IP address and the port number of router, this will tell the coming package which port send to. These operations are run on the Network layer, Ethernet layer and Physical layer.