Focusing on the port mode allows the switch to be cleverly switched

In a LAN with a relatively large scale, if the cascade position of the sub-switch changes, the virtual subnet previously divided in the sub-switch usually does not function. In this case, when the cascade position of the sub-switch changes, do we need to re-divide the VLAN so that all the virtual subnets can be accessed through the switch?

In fact, we only need to adjust the working mode of the new cascade port of the sub-switch so that the sub-switch does not need to re-divide the virtual subnet, allow all the virtual subnets to access the vswitch. Now, I will take the LAN as the operating blueprint to introduce the specific operation steps for modifying the working mode of the sub-switch cascade port.

Switch placement requirements

Assume that vswitch J1 is placed in Floor 1, vswitch J2 is placed in Floor 2, and the entire LAN is divided into six virtual subnets. Later, with the expansion and upgrade of the LAN, the Unit purchased some new network equipment. Now we want to place the switch J1 in Floor 2, in addition, the vswitch is connected to vj2 through a twisted pair cable on port 36. In addition, it is expected that the change in the position of vswitch J1 will not affect the division of existing virtual subnets, vswitch J1 was previously connected to a core layer-3 switch in the LAN through a fiber optic cable in port 22.

Switch placement settings

To avoid re-division of the virtual subnet of a unit, you only need to log on to the J1 and J2 backend configuration interfaces of the switch and modify the port working mode, the specific modification steps are as follows:

First, log on to the J1 system of the vswitch to view the relevant port parameter information of the vswitch. When viewing port parameters, we only need to execute the string command "display interfaces" on the backend management interface of the switch, so that the detailed port information of the switch will be displayed. Here, the parameter of the J1 directly cascade with vswitch J2 on port 36 is "interface ethernet0/36, port access vlan 4 ", from this result, we can find that vswitch J1 only belongs to vlan4 at this time, that is, only workstation from vlan4 can access the network through this vswitch, workstations in any other virtual subnet do not have access to the network through the vswitch. To allow all the virtual subnets in the LAN to access the network through the J1 switch, we only need to change the port working mode in this switch to the "trunk" mode, without any modification.

Some may wonder why J1 can communicate directly with the LAN before its location changes? In fact, when vswitch J1 is directly connected to the core layer-3 switch, it is connected through the fiber optic cable on the fiber optic port of the vswitch, the working mode of the optical fiber port has also been set to "trunk. When the position of vswitch J1 changes, the fiber port of vswitch J1 has no effect because it is connected to vswitch J2 through a common twisted pair cable.

Next, we need to modify the working mode of the cascade port of the vswitch J1 to ensure that the working mode of the port is "trunk. When modifying the port working mode, we can execute the string command "system" on the backend management interface of the switch to switch the system status to the parameter configuration status; then, run the "interface ethernet 0/36" command in the command line configuration status to enter the configuration status of the target connection port of the switch, in the command line status, enter the string command "port link-type trunk" and click the Enter key. Then, the cascade port working mode of the vswitch J1 is successfully modified to the "trunk" mode, finally, execute the string command "port trunk permit vlan all" to ensure that all the virtual subnets in the LAN can access the network through the cascade port of the vswitch J1. After completing the preceding configuration operations, follow the same steps to log on to the background configuration page of vswitch J2 to modify the target cascade port working mode of vswitch J2, make sure that the port is also in trunk mode.

1. Use commands to configure vswitch ports
2. The LAN connection is slow because the port mode does not match.