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On Tue, 18 Jan 2011, Malcolm Blackmore wrote:
I realise that I do not have a clue how FO operates to connect devices to it if one was to run a fibre into each room with multiple devices in the room to connect up to. Is it one strand per device in a multi stranded cable which needs to be terminated to a plug or socket? Or does the cable consist of a fibre or set of fibres that operates as a "bus" with packet addressing etc. ensuring that appropriate devices are communicated with discretely?
Fibre Optic Ethernet is typically a "star" topology with a central hub/switch device (or heirarchy of switches) with one cable per device. The cable itself may actually be a pair of fibre optic cables - one for transmit and one for recieve. (although there are technologys that will put both on the same fibre)
Addressing (if it's Ethernet) is carried out in the same way any other Ethernet addressing works. (MAC addresses, etc).
So at that level, you might as well just consider it to work the same as copper Ethernet as far as IP is concerend, ie. for home/office home wiring, it's not really different from copper ethernet in terms of the way you'd run the cabling.
So for fibre to the home, BT (or whoever) will end up running one fibre cable (which might be a pair) to each home from a central point (e.g. street cabinet) just like they do now with copper. I'm not sure if BT are running IP directly or encapsulated in (say) PPP. For FTTC where you get copper to the home, they are encapsulating IP in PPP, so they might do that for the Fibre.
Commercial leased lines (that I've used) give you raw access to the fibre and are often presented with an Ethernet socket to connect to ordinary 10/100/1000 Ethernet... Put a packet in one end and at the speed of light it popps out at the other...
Other technologies (not "Ethernet") may use a bus type topology with each station having an "in" and an "out" connector - token ring extends this to connecting the last to the first, but no-one remembers Token Ring anymore. (I did use it, once upon a time...)
The only other fibre technology you might find is FibreChannel - used to connect storage devices to servers. It's similar to Ethernet, but a bit more specialised for disks/SANs and can have switches as well as working point to point (direct server to storage array)
(But note that fibrechannel can work over copper too!) Gordon -- The Mailing List for the Devon & Cornwall LUG http://mailman.dclug.org.uk/listinfo/list FAQ: http://www.dcglug.org.uk/listfaq