Ethernet Hub – How Does an Ethernet Hub Work Internally?

Detecting link on a port is not done using ethernet frames, but with electrical pulses known as normal link pulses. If no frames are being sent, a device puts these on the wire every 16 ms (+/- 8 ms). They are also used for autonegotiation.

A link is considered down if no frames and no pulses are received. Receiving the pulses will make a Cisco tell you the port is up, but as we all know, it is perfectly possible to have "FastEthernet0/0 is up, line protocol is down".

The normal link pulses are not frames, and will not be forwarded by hubs or switches.

Keepalive frames are forwarded or switched, and can be used to detect a loop.

It's either a hub or a switch. They're not the same thing: switches use packet switching to determine who the recipient is and forward traffic on to that port only. Hubs offer poorer performance, to say the least, because they repeat all incoming traffic they receive on one port to all the other ports without checking to see who actually wants the packets.

I would strongly encourage you to use switches if what you have now are actually hubs. What are the model numbers?

You have already answered your own question about the speed. Plug in your ethernet run to a device at each end and see what speed each hub/switch auto negotiates to. The different LED colors are there to quickly check what speed a port is running at without having a computer handy- perfect for your needs.

Lastly, have a look at this IP camera bandwidth calculator. It may help you decide if you need 1000 mbps. You may easily get away with a 100 mbps network if all that's connected are the four cameras. However, I would again encourage you to use switches instead of hubs. In my experience, it will alleviate many problems and headaches before they even begin, and the price is essentially the same!