Why switches are better than hubs

As a result, all the computers receive the traffic, even if it is not for them. A switch is more intelligent than a hub.

As a hub, a switch is the connection point for the computers and other devices in a network. However, a switch is more efficient at passing along traffic. It records the addresses of the computers connected to it in a table. When traffic comes through, the switch reads the destination address and sends that traffic to the appropriate computer rather than sending it to all the connected computers.

If the destination address is not in the table, the switch sends the traffic to all the connected computers. A router is the most intelligent of the three hardware devices.

It is typically a small computing device designed specifically to understand, manipulate, and direct traffic. Routers include a user interface so that you can tell them where to direct the traffic.

The primary function of a traditional router is to connect two or more networks or network segments in a very large network and direct traffic between them.

It is used to connect segments of a LAN. A hub stores various ports, so when a packet arrives at one port, it is copied to various other ports. Hub works as a common connection point for devices in a network.

A network switch is a computer networking device that connects various devices together on a single computer network. It may also be used to route information in the form of electronic data sent over networks.

They are termed as a network bridge with multiple ports that which use media access control MAC addresses to receive and forward the data to the destination devices. All these three devices function differently, even if they are combined into a single device. So, it is important to know which device you should choose depending upon your requirement. This post discusses further details on hubs, switches, routers, their types such as fiber optic switches or Ethernet switches, and features.

These devices are different from each other in features and functionality, and it is important to understand them before making a decision. Some individuals would call this a bridge. On each side of the switch is a transceiver. Each Ethernet transceiver provides a physical end to an Ethernet wiring segment and the actual end of the network diameter.

Therefore, one two-port Ethernet switch links two separate Ethernet networks. Since there is no distinction between one device on one network versus another device on the other network, the two networks function as one larger network.

In this case a switching hub and repeating hub function in a similar manner. However, there is one big difference. A switch port stores the complete frame before it passes it to the other port. It does this because it needs to know the destination of the received frame and to verify that a valid frame was received by observing the frame check sequence. If the frame is invalid, it should be discarded instead of forwarding a faulty frame.

Since the switch must store one complete frame before forwarding, the delay in observing the frame on the other port is at a minimum one frame. Since frame sizes can vary, the delay can vary. At 10 Mbps and the shortest frame, the delay is Is this a problem?

Not necessarily. Assume we are going to send a message consisting of Ethernet frames, and we were fortunate to be able to send them back-to-back with the minimum interframe gap. What would be the data latency due to the switch? The answer is still only one frame's worth.

Therefore, by either sending out one frame or frames, the switch only queue's one frame's worth of data under normal conditions. Therefore, it would appear that switch latency is not an issue.

Let us study the situation closer. The slave only responds to requests by the master and never initiates a request itself. Further assume that the two devices are separated by a switch.

If the master initiates a one-frame message there will, of course, be a one-frame delay before the slave receives the message. The slave acts upon the request and initiates a one-frame response which also incurs a one-frame delay.

If both frames were long, a total of 2. Now if we substitute a hub for the switch, we would not suffer the 2. Now someone might take issue with my example by saying that by using a repeating hub, I could potentially introduce collisions on the network that would reduce performance.

That is true, but let us study the protocol. Once the master senses a quiet line, it initiates a transmission and then waits for a response from the slave. The only slave to respond was the one polled.

The master consumes the response and then initiates another command to another slave. Your most popular industrial protocols such as Modbus and Optomux operate this way. Therefore, my example is valid.