On the test, I will configure the Cisco Catalyst WS-C3750-48TS-S.
And so, all ports are configured as access, except for the first Gigabit uplink port, it is configured as a trunk and the Internet on the client vlan with the tag comes to it.
We need all the ports on this switch to not see each other and see only the first gigabit ulink port.
To do this, connect to the switch and go into the configuration mode:
enable configure terminal
Then, we issue the switchport protected command for all access ports:
interface range fastEthernet 1/0/1-48 switchport protected interface range gigabitEthernet 1/0/2-4 switchport protected exit exit
Save the configuration:
Apparently interface gigabitEthernet 1/0/1 we did not touch.
Now the ports on which the switchport protected command is registered do not see the other ports on which this command is also registered, they see only the ports where it is not registered, that is, in our case the first gigabit ulink port, and it sees all the ports with the command and without.
Information about ports can be viewed by the command:
show interfaces NAME switchport
View full configuration: