A comprehensive explanation of the TRUNK configuration function in the core switch

The core switch is still quite common, So I studied the TRUNK configuration function of the core switch. Here I will share it with you and hope it will be useful to you. What is TRUNK? What application advantages can TRUNK bring to us? How to configure the TRUNK in a specific core switch product? Let's take a look at these knowledge.

An important indicator is often mentioned in the performance parameters of L2 switches: TRUNK. Many L2 Switch products will mention that it can support the TRUNK function when introducing its performance, this can provide better Transmission Performance Between Interconnected switches. So what is TRUNK? What application advantages can TRUNK bring to us? How to configure the TRUNK in a specific core switch product. Let's take a look at these knowledge.

1. What is TRUNK?

TRUNK indicates port aggregation, that is, by configuring the software settings, combine two or more physical ports into one logical path to increase the bandwidth between the vswitch and the network node, and merge the bandwidth of these ports, the port is provided with a high bandwidth that is several times the exclusive bandwidth of the Independent Port. Trunk is a encapsulation technology. It is a point-to-point link. both ends of the link can be a switch, a switch, a router, or a host, a core switch, or a router. Based on the port aggregation Trunk) function, allows the switch and the switch, the switch and the router, the host and the switch or the router to be concurrently transmitted through two or more ports to provide higher bandwidth and higher throughput, the entire network capability is greatly provided.

Generally, when TRUNK is not used, we all know that this transmission medium feature of the 10/100 M Ethernet twisted pair determines that the bandwidth of the two common 100 switches is only M, if the full duplex mode is used, the maximum bandwidth for transmission can reach 200 MB, which forms a network trunk and server bottleneck. To achieve a higher data transmission rate, you need to change the transmission media, use a gigabit optical fiber or upgrade to a Gigabit Ethernet, although the bandwidth can reach a Gigabit, but the cost is very expensive, and even core switches need to be replaced). This is not suitable for low-cost SMEs and schools. If the TRUNK technology is used, four ports are bundled together to achieve mbps bandwidth, which can better solve the contradiction between cost and performance.

II. Specific Application of TRUNK

TRUNK port aggregation) is a more economical way to increase bandwidth between the core switch and network equipment, such as servers, routers, workstations, or other core switches. The method to increase the bandwidth is effective when the connection between a single switch and a node cannot meet the load.

The main function of TRUNK is to bind multiple physical ports to a logical channel, which works like a channel. Bundling multiple physical links not only improves the bandwidth of the entire network, but also data can be transmitted through multiple bound physical links at the same time, which has the function of link redundancy, when one or more links are disconnected due to network faults or other causes, the remaining links can still work. However, in VLAN data transmission, different manufacturers use different technologies. For example, Cisco products use vlan trunk technology. Most products of other manufacturers support the 802.1q protocol with the TAG header, in this way, a small giant frame is generated and must be identified using the same port protocol. Because the size of a small giant frame exceeds the 1518-byte limit of the standard Ethernet frame, it cannot be identified by a common Nic and requires a switch to remove the TAG. The TRUNK function is suitable for the following applications:

1. The TRUNK function is used to connect to the server and provide the server with an exclusive high bandwidth.

2. The TRUNK function is used for cascade between core switches. By sacrificing the number of ports, it provides bundled high bandwidth for data exchange between switches, improving network speed and breaking through network bottlenecks, this greatly improves network performance.

3. Trunk can provide load balancing capabilities and system fault tolerance. Because Trunk balances the traffic of each core switch port and server interface in real time, once a port fails, it will automatically remove the faulty port from the Trunk group, in this way, the traffic of each Trunk port is re-allocated to implement system fault tolerance.

Iii. Precautions for TRUNK Configuration

In a TRUNK, data is always from a specific source point to a destination point, and a single link is designed to process broadcast packets or uncertain packets. When configuring TRUNK, you must follow the following rules:

1: correctly select the number of TRUNK ports, which must be 2, 4 or 8.

2: the ports in the same group must be used. The ports on the core switch are divided into several groups. All ports of the TRUNK must come from the same group.

3: Use Continuous ports. The ports on the TRUNK must be continuous. For example, you can combine ports, 6, and 7 into a port aggregation.

4: generate only one TRUNK in a group of ports.