Differences between bridges and Routers

Differences between routers and bridges
The second layer in the OSI model, that is, the link layer. The main purpose of data Frame Forwarding is to provide transparent communication between Connected Networks. Bridge Forwarding is based on the source address and destination address in the data frame to determine whether a frame should be forwarded and to which port. The address in the frame is called the "Mac" address or "hardware" address, which is generally the address of the NIC.

A bridge connects two or more networks to provide transparent communication. Devices on the network cannot see the existence of a bridge, and communication between devices is as convenient as on an Internet. Because the bridge forwards data frames, it can only connect to the same or similar network (data frames of the same or similar structure), such as between Ethernet, Ethernet and Token Ring) for different types of networks (different data frame structures), such as Ethernet and X.25, the bridge is powerless.

Bridges expand the network scale, improve network performance, and facilitate network applications. In the past, bridges were widely used. However, bridge interconnection also brings many problems: one is a broadcast storm, where the bridge does not block the broadcast messages in the network. When the network size is large (several bridges and multiple Ethernet segments ), broadcast storm may occur, and the whole network is full of broadcast information until it is completely paralyzed. The second problem is that when connecting to an external network, the bridge combines the internal network with the external network to become a network, and both parties automatically open their network resources to the other party. This interconnection method is obviously unacceptable when it is connected to an external network. The main cause of the problem is that the bridge only maximizes network communication, regardless of the information transmitted.

The Layer 3 router in the OSI model, that is, the network layer. Vrouters use network addresses (IP addresses) defined in the "logic" of the network layer to differentiate different networks, achieve network interconnection and isolation, and maintain the independence of each network. Vrouters do not forward broadcast messages, but restrict broadcast messages to their respective networks. Data sent to other networks is first sent to the vro and then forwarded by the vro.

The IP router only forwards IP groups and blocks the remaining parts in the network (including broadcast), so as to maintain the independence of each network. In this way, many networks (subnets) can be formed) large interconnected networks. Because of the interconnection at the network layer, the router can easily connect different types of networks. As long as the network layer runs the IP protocol, the router can connect.

A vro has multiple ports used to connect multiple IP subnets. The network number of the IP address of each port must be the same as the network number of the connected IP subnet. Different ports have different network numbers and correspond to different IP subnets. In this way, the hosts in each subnet can send the requested IP addresses to the vro through their own subnet IP addresses.