For the experiment, let us use three Planet GT-802S media converters (as in the above image) and three 1 metre lengths of single-mode optical fibre with SC/PC connectors at each end.
Lay out the media converters to form an equilateral triangle and label them MC-1, MC-2 & MC-3. Now connect the TX port of MC-1 to the RX port of MC-2, the TX port of MC-2 to the RX port of MC-3 and the TX port of MC-3 to the RX port of MC-1.
Power on the media converters. What happens? Is there a manic storm through the fibre links? Or does calm sanity prevail?
If calm sanity prevails we then proceed with the second part of the experiment. Let us connect a CPE (which will be providing Internet access) and two computers to the three media converters. The CPE does not have a DHCP server enabled on its LAN ports. For simplicity, the CPE has been assigned the 10.10.10.10 IPv4 address. Connect the LAN1 port of the CPE to MC-1 with a standard Ethernet patch cable. With similar length Ethernet patch cables, connect computer one to MC-2 and computer two to MC-3. Computer one has been assigned the 10.10.10.20 IPv4 address and computer two has been assigned the 10.10.10.30 IPv4 address. (Both computers are configured with a gateway at the 10.10.10.10 IPv4 address.)
Are the two computers able to access the Internet? Are the two computers able to access each other?
The idea of this thought experiment just "appeared", a couple of nights ago, whilst I was inspecting the insides of my eyelids. Isn't it strange how the mind operates when it is just idling!