Basic vswitch knowledge and common related terms

A Switch is a device that can complete information exchange in a communication system based on MAC address (NIC hardware identifier) recognition. The working principle can be simply described as "Storage forwarding". For example, two computers (A and B) are connected through A switch. If A wants to transmit data to B, the switch can first store the information sent to port A, and then find the MAC address list in the switch. Each MAC address corresponds to A computer, after finding it, a temporary dedicated data channel will be set up with B and the data will be sent to B (see figure ). Because the switch supports the "full duplex" mode, B can send data to A or other computers while receiving data from. If the MAC address does not contain B's address information, the switch can use the "MAC address learning" function to remember the MAC address of the computer B connected to it, form a table corresponding to the node and MAC address.

Currently, there are many types of vswitches available on the market, which can be divided into five ports, eight ports, 16 ports, and 24 ports; the transmission rate can be divided into 10 Mbps switch, 100 Mbps switch, 10 Mbps/Mbps adaptive switch, 10 Mbps/Mbps adaptive switch, and Mbps switch. Let's take a look at the performance parameters of the vswitch.

IEEE 802.3 standard: the IEEE 802.3 standard refers to the Ethernet standard and defines the transmission rate as 10 Mbps. the IEEE 802.3u standard refers to the Fast Ethernet standard and defines the transmission rate as 100 Mbps; the IEEE 802.3ab standard is a Gigabit Ethernet (unshielded twisted pair) standard with a transmission rate of 1000 Mbps. the IEEE 802.3x standard generally refers to the traffic control standard, which can be used to control the traffic of Ethernet hosts, ensure that the communication will not be lost on the full-duplex link with high throughput during peak communication rate. The purchased vswitch products generally follow multiple standards in the IEEE 802.3 series.

Exchange mode: refers to the way the switch transmits data. For example, the mainstream exchange mode is Store and Forward. This mode is used when the switch receives all data packets and then forwards them. In addition, there is a Cut Through method, which starts to forward data before the switch receives the entire packet.

Packet forwarding rate: the speed at which the switch forwards data packets. The unit is pps (packets per second). Generally, the packet forwarding rate of a switch ranges from dozens of kpps to hundreds of kpps, the larger the packet forwarding rate, the faster the network speed. Full duplex, half duplex, and packet forwarding rate at different port rates are different.

Backboard bandwidth: refers to the maximum data volume that can be handled by the vswitch interface processor and the data bus. The wider the backboard bandwidth, the better. It is one of the key indicators to measure the data processing capability of the vswitch. At present, the bandwidth of a desktop switch with five or eight ports is generally 1 Gbps ~ Between 8.8 Gbps, the bandwidth of the professional switch board is higher. For example, the bandwidth of the general Gigabit Switch Board can reach Gbps.

VLAN: The full name is Virtual Local Area Network (VLAN). Through the VLAN function of a switch, you can logically divide LAN devices into Network segments (or smaller LAN ), in this way, the data exchange technology of the virtual working group is realized. VLAN can also prevent the LAN from generating broadcast effects and enhance management and security between network segments.

STACK: a dedicated connection cable is used to connect two or more switches to one another. For example, to connect two switches, you can directly connect to the DOWN stack port of another stack switch from the UP stack port of one stack switch to expand the number of ports of a single switch.

Tip: When purchasing a switch, pay attention to the standards and protocols supported by the switch, ports, transmission media, switching methods, packet forwarding rate, and board bandwidth. for enterprise-level switches, note whether VLAN and stack functions are supported.