Firstly, I'm not responsible for the equipment, so don't panic that I'm asking such basic questions :)
At work we have multiple RS232 / Ethernet port servers (Say the 16 port version of this http://www.digi.com/products/serialservers/portserverts)
I have basic understanding of the OSI model and how protocol's at different layers interact. For example http being encapsulated in TCP packets using IP, which in turn are encapsulated in ethernet frames for the router layer using MACs etc etc.
I'm having trouble getting my head around what protocol is actually being transmitted in the cat5 cable of these port servers however. Is it straight RS232 which has simply had the wires remapped to an ethernet cable? Is it RS232 protocol encapsulated in some ethernet protocol (Ethernet is LLC / MAC yeah?)? Am I getting protocol's mixed up - i.e. RS232 and LLC is at the same level?
The motivation for the question stems from my work currently paying a couple of grand for serial analysers. Essentially it plugs inline with the cat5, is converted into a physical RS232 plug, has the tap with a USB output, and the reverse happens to have cat5 continuing again. I'm wondering why I can't make something like a simple passive ethernet network tap, and use two ethernet NICs bonded together and monitor the application protocol with wireshark. To research this further I'm trying to find exactly what protocol would be sent around in the port servers.