Can a smart switch replace a hub?

If the network bandwidth is not wide and the speed is not fast, it takes a lot of time for each packet to be transmitted, then there will be no more channels, and the network transmission efficiency is still not high, this depends on the bandwidth. Currently, the fastest Ethernet switch bandwidth can reach 10 Gbps.

The switch was initially designed to solve the problem of hub shared transmission media. The port bandwidth was too narrow and it was prone to broadcast storms. The original switch was the second layer in the OSI/RM open architecture, this is also called the second layer switch. We will continue to introduce the switch classification in the next article ).

This section describes the differences between a vswitch and a hub. In other words, what are the advantages of a vswitch, after understanding the differences between them, we can correctly understand why vswitches are widely used in the current LAN, rather than hubs, and make it easier for us to choose the right option for future network devices.

The differences between a smart switch and a hub are mainly reflected in the following aspects:

1) different layers of work in OSI/RM

The layers of switches and hubs in the OSI/RM open system model are different. The hubs work at the first layer of the physical layer) and the second layer of the data link layer ), vswitches should at least work on the second layer, and more advanced switches can work on the third layer network layer) and the fourth layer transport layer ).

2) the data transmission modes of vswitches are different.

The data transmission mode of the hub is broadcast, while the data transmission mode of the switch is purposeful. Data is only sent to the target node, only when the MAC address table cannot be found, the broadcast method is used for the first time. Then, because the switch has the MAC address learning function, broadcast transmission will no longer be performed after the second time, it is also a purposeful sending. The advantage is that the data transmission efficiency is improved, so there will be no broadcast storms, and no listening from other nodes in terms of security. The specific analysis has been made before, and I will not go into details here.

3) bandwidth usage is different

In terms of bandwidth usage, all the ports of the hub share the total bandwidth of the hub, and each port of the switch has its own bandwidth, in this way, the bandwidth of each port of the switch is much higher than the available bandwidth of the hub port, which determines that the transmission speed of the smart switch is much faster than that of the hub.

4) different transmission modes

The hub can only transmit data in half duplex mode, because the hub is a shared transport medium. In this way, the hub can only transmit one task at a time on the uplink channel, either receiving data or sending data. The switch is different. It uses the full duplex mode to transmit data.

Therefore, data can be received and sent at the same time, which not only speeds up data transmission, but also speeds up the throughput of the entire system by more than twice as high as that of the hub, because it can receive and send at the same time, it is actually far more than doubled, because the port bandwidth is generally many times wider than the hub.

Iii. Working Principle of vswitches

Smart switches and hubs are very similar in appearance and follow the IEEE 802.3 and its expansion standards. The media access methods are also CSMA/CD. However, they still have fundamental differences in working principles. Simply put, a network built by a vswitch is called a switched network. Each port can enjoy an exclusive bandwidth. All ports can communicate simultaneously and provide double transmission rates in full-duplex mode.

The network built by the hub is called a shared network. At the same time, only two ports can receive data and the port for sending data) for communication. All ports share the inherent bandwidth. The following is a simple illustration.

　1. "sharing" and "Exchange" Data Transmission Technology

To understand the advantages of a smart Switch, we must first understand the basic working principle of the Switch. The most fundamental principle of the Switch is to understand "Share" and "Switch) these two concepts. The Hub uses the Shared Mode for data transmission, and the switch principle we will talk about here is to use the "Exchange" Mode for data transmission.

We can understand "sharing" and "Exchange" as roads. The "sharing" method means that the back-and-forth vehicles share a single-lane road with one driveway, while the "switching" method means that the back-and-forth vehicles use a two-lane road with one driveway, the "share" and "Exchange" data transmission methods are shown in the left and right figures respectively.