Hello everyone!
Today, I will continue to explain a new way to structure a telecommunications network – OLAN. Now, I will explain one of three types of OLAN – FTTD.
As I said in the previous article, there are three types of OLAN:
FTTD or centralized fiber,
FTTO, and
Passive Optical LAN.
FTTD is an abbreviation from Fiber To The Desk. The architecture of this solution is as follows: from main hubs or switches (which are in the computer room) to fiber patch panels and "desk" in a room, there are optical cables (centralized fibers and zip cord). We can see this type of OLAN, in the next figure.
Centralized fiber terminates on an optical patch panel. From the optical patch panel to the media converter are optical cables with two fibers - a zip cord. One fiber is used for the forward direction, the other fiber for the return direction. All optical fibers are multimode fibers (usually OM2, OM3 and OM4) and are used at a wavelength of 850 nm (the source is VCSEL). Multimode fibers use adhesive/polish optical connectors or prepolished/splice optical connectors.
Figure 1. Traditional LAN and FTTD
Fiber optics terminate at the media converter. Media converter converts optical signal to electrical signal. It has optical input ports (fixed-fiber connectors) of SFP transceiver for two optical connectors and one ethernet port - RJ45. Typical, one host can be connected to the Ethernet port. Some media converters support PoE, PoE+, HPoE and IEEE 802.3bt. Except for this option, some media converters have up to four RJ-45 ports (in this situation, we have enough ethernet ports for four hosts).
There are variants, if we have more hosts in a room, that there are more media converters or another better option is to connect a switch to the media converter and thus enable the connection of more hosts. After media convertor, we can use standard UTP cables cat 5 for connecting hosts.
Figure 2. FTTD
If we look at OLAN - FTTD, we can state the following: the price of optical cables are lower than the price of copper cables, the need to power the device is less, optical cables take up less space. This technology is advantageous because it has higher bandwidth, optical cables are immune to interference, it allows hosts to connect over longer distances, and so on.
I will continue to explain this theme in the next article >> OLANs(3): FTTO
Thank you!
