Hi,
You can have a cascade of hubs connected via their uplink ports.
ASCII ART TIME
HUBu <--> HUBu <--> HUBu <--> HUBu <--> HUB <--------Mac
Uplink ports are nothing more than "built in" crossover connections. You take a normal hub port, and place it into a connection of an Uplink port on a different hub upstream.
Thou shalt not:
* Connect 2 hubs together via normal ports and normal wires
* Connect a hub and a computer together via uplink port and normal wire
* Use uplink ports and crossover cables
It is bad networking practice to have more than one or two uplink ports in the chain between the PC and the "route out", because all of the traffic of that hub is being supplied by that one uplink port. Performance can fall apart in a hurry.
In most office environments, little hubs can be used at the user's desk to avoid the expense of running wires through the walls. You would connect the little hub to the main system via the uplink port, and have the user's computer and perhaps laptop wired into the system via the remaining ports.
What you don't want to see is a hub in the cube, uplinked to a hub for the department, uplinked to a hub for the floor, uplinked to a hub in another closet, uplinked to the main computer room.
Christian