The difference between hubs and switches and the classification of switches

Switch switches in place, replacing the original hub hubs.

First, let's start with a simple understanding of the differences between switches and hubs. The hub uses the shared bandwidth of the work, simple for example, the hub is like a one-way street, "10M" bandwidth is used in multiple ports, when a port occupies most of the bandwidth, the other port will appear very slow. Instead, the switch is a unique channel that ensures that each port uses bandwidth, such as a hundred gigabit switch, to ensure that each port has a gigabit bandwidth.

Because switches have an obvious advantage over hubs, the current hubs can almost be said to be extinct. The more important factor is that the price of the switch continues to decline, in the performance of cost-effective, the hub can not exit the "lake".

Now, the network equipment market for the switch has a lot of different names, to a large extent, the different brands between the name of the switch, the author roughly divided into several types of switches: ordinary switches, network management switches, three-tier switches and modular switches.

General switch

This good understanding, is what function does not have, simply is the support data transmission function.

Network Management switch

This means that the device can be used for management, such as the partition VLAN of the port, the limitation of data traffic, etc.

Three-layer switch

Three-layer switch is a relatively high-end equipment, in the general family or small enterprises will not be used, the three-tier switch has a routing function, mainly to connect the use of the distribution layer switch.

Modular switch

This kind of equipment has the very strong application ability, it may make the different solution by the different use environment. Many of the devices are empty chassis, plus different modules, such as fiber-optic interface and RJ-45 port (LAN and WAN), so as to achieve voice, data and other functions. The advantage of this equipment is flexibility, but the price is very high.

In addition to understanding the above mentioned things, we need to pay attention to equipment when purchasing some technology, such as data exchange Mode, backplane bandwidth and port rate of the relationship between the extensible device port type and so on.

One or three ways to exchange data

Cutthrough: Package data packet into the switching engine, in the specified time dropped to the Backplane bus, and then sent to the destination port, this Exchange Mode of Exchange speed, but easy to lose packet phenomenon;

Store&forward: The package packet enters the switching engine and is provided with a buffer, which is forwarded by the switching engine to the Backplane bus, which overcomes the packet loss, but reduces the switching speed;

Fragment Free: A solution between the above two.

Second, back plate bandwidth and port speed

The switch hangs each port on a high bandwidth backplane bus (Corebus), and Backplane bus is the backplane bandwidth. The port rate is the number of packets per second that the port is throughput.

Third, modular and fixed configuration

There are only two switches from the design concept: One is a chassis switch (also known as a modular switch), and the other is a stand-alone fixed configuration switch.

The biggest feature of the chassis switch is its strong scalability to provide a range of extension modules, such as Gigabit Ethernet modules, FDDI modules, ATM modules, Fast Ethernet modules, Token Ring modules, and so on, so that networks with different protocols and topologies can be connected. Its biggest drawback is that the price is expensive. Chassis switches are typically used as backbone switches.

Fixed configuration switches, typically with fixed port configuration. Fixed-configuration switches are less scalable than chassis switches, but costs are much lower.

After talking about these, I believe that we have a preliminary concept of the switch.