Hello everyone!
In the previous article, I explained one of three types of OLAN – FTTD. Today, I will continue to talk about OLANs, now, I will explain the second type of OLAN. It is FTTO. Let's started.
As I said in the first article about OLANs, there are three types of OLAN:
FTTD or centralized fiber,
FTTO, and
Passive Optical LAN.
FTTO is an abbreviation from Fiber To The Office. The idea is to use ethernet switches for connecting hosts. The architecture of this type of OLAN is similar to FTTD. From main hubs or switches (which are in the computer room or main equipment room) to fiber patch panels (passive), there are optical cables (centralized fiber). After that, from fiber patch panel to local ethernet switches, there are optical cables – tight buffer simplex. Every switch has two fibers to connect to the main switch in the main equipment room. Then, we can use standard UTP cables cat 5 for connecting hosts on the work area switches. We can see this type of OLAN in figures 1. and 2.
Figure 1. Traditional LAN and FTTO
All optical fibers are singlemode (SM) fibers (OS1 and OS2), with prepolished/splice connectors or factory terminated. Usually, OS2 singlemode fibers are used because this type of SM fiber can easily carry a signal of 100 GHz bandwidth up to 5 km. For full duplex connections, local ethernet switches are connected by two optical fibers transmitting in opposite directions. Sometimes, we can use composite cables for the power supply of the devices.
Generally, we can talk about three main segments in FTTO:
The passive elements. This segment consists optical cables (backbone, horizontal and zip cord), optical patch panels, optical closures, etc.),
The active elements. These components are core or central switches and the local switches. Core or central switches are in the computer room. They are drivers for the system. And local switches convert the media transporting data, from optical signal to electrical signal. And,
The power supply – PoE (Power over Ethernet). Switches can support PoE. These switches enable power supply for devices, with this capability.
Figure 2. FTTO
As I said in two last articles, the price of optical cables is 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, 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 (4): Passive Optical LANs
Thank you!
