I'm configuring a cisco catalyst switch and I want to change the vlan for the all of the ports on the switch away from the default vlan 1. I know how to change a vlan on an interface, I want to know if the traffic will be stopped when I do the switch and if this is something I am able to do while the switch is live.
The answer is Yes and No. You can make the changes, BUT hosts and devices won't be able to communicate with each other until and unless the ports they're connected to are members of the same VLAN. So if hosts 1 and 2 are connected to ports 1 and 2 in VLAN 1 and you make port 1 a member of VLAN 2 then hosts 1 and 2 won't be able to communicate until you make port 2 a member of VLAN 2.