I need to take a 24-port Catalyst switch and basically carve it up into four distinct six-port switches. Each "switch" needs to be completely isolated from the other "switches". I assume VLANs would be required here, however the traffic needs to be free of any VLAN tagging, as it's connected to ISP equipment. These VLANs only need to exist on this one switch. How can this be done so there is no tagging whatsoever?
The longer story (though not completely required) is that we have three ISPs in our office and a redundant pair of Internet routers. Since the ISP equipment only has one port each, this Catalyst switch would split the ISP traffic to each router, as only one will be active at a time, using each of the first three VLANs. Then the LAN traffic from the routers would use the fourth "switch" VLAN to combine links before hitting the office LAN. Image attached.