Switches are the common equipment for data forwarding in local area networks(LAN), and their performance and functions determine the manageability and data forwarding performance of the LAN. The following aspects should be considered when choosing a switch: Number of ports The number of physical ports supported by the switch determines the number of terminals or secondary devices connected to the switch, which need to be selected according to actual needs. Of course, subsequent network expansion needs to be considered. The access port of the switch is used to connect the internal network terminal, and the uplink port is used to connect to the upper-level equipment. 2.Port Speeds and Types Switches come in Fast Ethernet and Gigabit Ethernet. Fast Ethernet allows up to 100 Mb/s of traffic per switch port while Gigabit Ethernet allows up to 1000 Mb/s of traffic per switch port. These ports may be a combination of SFP/SFP+ slots for fiber connectivity, but more commonly they are copper ports with RJ-45 connectors on the front, allowing for distances up to 100 meters. With Fiber SFP modules, you can go distances up to 40 kilometers. Currently, Gigabit Ethernet is the most popular interface speed though Fast Ethernet is still widely used, especially in price-sensitive environments. 3.Switch access capacity The amount of equipment attached to the switch is mainly reflected in the depth of the MAC address table of the switch. At the same time, it is also necessary to pay attention to the number of host routing entries for the three-layer switch. For example, when selecting a Layer 3 switch, the number of all access terminals of the Layer 3 switch is required to be less than the number of host routing entries of the Layer 3 switch. 4.Network scale and switch network structure Considering the scale and level of switch application networks, which are mainly divided into small and medium-sized networks and large and medium-sized networks, the recommendations are as below: 5.Functional support Divide VLANs to realize that ports belonging to different VLANs can’t communicate with each other; Set static routes to realize that VLANs of different network segments can communicate with each other; DHCP snooping prevents the access of other DHCP servers from affecting the LAN. The above functions are commonly used in large and medium LANs. 6.Safety function Specifically, such as: Access Control List, 802.1X authentication(Radius,Tacacs+), loopback detection, IGMP Snooping, etc. 7.Power requirements At any layer, a modern switch may implement power over Ethernet (PoE), which avoids the need for attached devices, such as a VoIP phone or wireless access point, to have a separate power supply. Since switches can have redundant power circuits connected to uninterruptible power supplies, the connected device can continue operating even when regular office power fails. Another characteristic you consider when choosing a switch is PoE. This is the ability of the switch to deliver power to a device over the existing Ethernet cabling. To find the switch that is right for you, all you need to do is choose a switch according to your power needs. When connecting to desktops which do not require PoE switches, the non-PoE switches are a more cost-effective option.