How 100BaseT hub’s Uplink port work?

Many of us know that we can use a UTP cable between the wall’s RJ45 outlet and a 100BaseT hub’s Uplink port so that we can string off more workstations.

I’d like to know what really happens, from a “logical” topology point of view.

1. Does this create a new “second” logical bus segment that strings off of the first?

Or…

2. Does this “lengthen” the original bus through that UPT cable to maintain a “single” logical bus throughout?

3. I could be wrong on both explanations. Can you help?

Thought I’d ask here first before I start calling up the hub manufacturers.

Many thanks and kind regards

Kyu
www.infouser.com