Hubs, bridges, switches, and routers work and how to choose their own models

These things all work differently in nature. The OSI stratification is different.

Hub: This is a layer 1 (physical) device, which means that it does not parse the transmission packets at layer 2 (i.e., does not distinguish between MAC addresses) and all devices connected to the hub are in the same collision domain (as if four households on the same road share the same road). Let's assume that four computers are connected to ab, c, d.

A sends data to D, and B C will receive this data, which will cause congestion when the security is very low and there are many devices (everyone is grabbing a line).

Switches: In order to solve this problem, a switch is created, which is a device at Layer 2 and will run the unpacket and packet work at the Layer 2 data link layer. Each switch port is an independent conflict domain (one dedicated road for four households), if the switch connects a b c d four computers a sends data to d, when the data arrives at the switch, it will be sent directly to d instead of transmitting to b c, effectively reducing the load on the link.

Router: This is a Layer 3 device, whether it is a switch or a hub, they do not need an IP address to communicate with each other, because they are in the same LAN (the switch uses a MAC address), when it is necessary to cross network segments. IP addresses are required to participate in this.

This is the most essential difference between the three of them.

Bridges function like routers and are generally done by software.

Image point metaphor:

The hub is a quadrangle, you just have to shout in the courtyard so that everyone can hear it, and then the person you call will respond to you, and everyone else will think that they don't hear it.

A switch is a closed community, and each house is independent. If you want to find someone, you need to find it directly through the other person's house number, and you can't shout in the whole community.

A router can be understood as a street sign between two neighborhoods, which is used to tell you how to go to another neighborhood.

What do you do with these, do you make a network?

1. Performance differences:

Hub. The mode of working is shared, while the switch is dedicated bandwidth. In this way, when there are many machines or a large amount of data, the two will be more obvious. The router carrier is significantly different from the above two, and its function is to connect different network segments.

In addition, it can be said that the demand for individual users is not large under normal circumstances.

The router is generated after the switch, just like the switch is generated after the hub, so the router and the switch are also related to a certain extent, and they are not completely independent devices. The router mainly overcomes the fact that the switch cannot route packets.

deficiencies. Second, the number of ports is different:

Ethernet switches, also known as switched hubs, are simplified (typical) bridges.

It is generally used to interconnect the same type of LAN (e.g., Ethernet, Ethernet, Ethernet). The difference between a switch and a bridge is that the switch has a larger number of ports; The data transmission efficiency of the switch is high.

Third, the physical layer is different;

The hub actually divides the network line into several lines at the physical level, so if the interface is used by several people, it will seriously affect the network speed.

The bridge is actually the predecessor of the switch, and the principle is basically the same, but with more useful functions. The hub is the physical layer device, and the bridge and switch are the layer 2 data link layer.

Equipment. <>

The hub creates a collision domain and a broadcast domain. The bridge separates the collision domains, but creates a large broadcast domain. They use hardware addresses to filter the network.

Switches are really just intelligent multi-port bridges that separate collision domains, but create a large broadcast domain by default. The switch uses hardware addresses to filter the network. Routers separate broadcast domains and filter the network using logical addressing.