Definitions and Terminology used in Optical Networks

Definitions and Terminology used in Optical Networks : Dear friends, in this article I will only talk about the definition and terminology which are used in optical networks. We can also say that all these terminologies are often used in connection with FTTH networks. 

Through this article, you will know all the Definitions and Terminology that you are often confused about. Suppose that you work in optical networks, you hear some words everyday, but in reality what is its definition is probably not known. With the help of this article I will try to overcome the trouble of friends who have heard some terminology, but they do not know the definition.

Definition and Terminology 

Definitions and Terminology used in Optical Networks

Terminology and Definitions

FTTH - Fiber to the Home : Access technology architecture that brings fiber optic cable from the exchange direct to customer's location at high bandwidth delivering triple play (voice, video and data) from a single fiber.

PON - Passive Optical Network : An architecture using optical transmission system designed to carry signals via fiber optic cable from the central office directly to end users such as businesses and multi dwelling units. Meaning of Passive is that there is no active or powered element or component in between the telecom exchange and the customer's location.

GPON - Gigabit Passive Optical Network : A flexible optical fiber access network cable of supporting bandwidth requirements of subscriber and covers system with nominal line rates of 1.2 Gbps and 2.4 Gbps in downstream direction; and 155 Mbps up to 2.4 Gbps in the upstream direction.

OLT - Optical Line terminal : Located inside the exchange and serve as the termination point of OSP Feeder fiber cables. An FTTH access platform designed for the GPON standard provides RF video and TDM voice services with ease, while IP provides a smooth migration path to triple play services.

FDF - Fiber Distribution Frame : Exchange termination equipment where fibers from OLT are split and jointed to Feeder cable when there is mass FTTH deployment.

ODF - Optical Distribution Frame : Location where fibers from OLT ports are terminated then interfaced to Feeder cable of FTTH.

MDF - Main Distribution Frame : Location where copper OSP cables are terminated inside the exchange make access to Network switch.

FDT - Fiber Distribution Terminal : A hub where all the fiber from the telecom provider's central office is split and distributed to the end users.

FAT - Fiber Access Terminal : A distribution point in the distribution end that distribute the all drop fibers to each customer. It can also divide the house to distribute drops in homes and offices.

ONT - Optical Network Terminal : A media converter typically installed outside / indoors or designed to deliver multi-line POTS, data and video.

ONU - Optical Network Unit : A unit located outside customer's area to serve more customers, similar to RAN.

FTB - Fiber Termination Box : Customer Lead-In Unit, installed at the customer outer wall for termination of incoming & indoor fibers.

Sp - Passive Optical Splitter : Split the signal bidirectionally from a single fiber to multi fiber without any power application.

Centralized Topology FTTH : The type of FTTH architecture where fiber optic cable from OLT is split only once before reaching customers.We mainly know the two types of Centralized FTTH topology namely: Central Office Homerun and Local Convergence Point.

Central Office Home-run : Type of Centralized FTTH architecture where splitters are located inside the central office & no splitting beyond.

LCP - Local Convergence Point : Type of Centralized FTTH architecture where splitters are concentrated in an FDT or a manhole outside the exchange.

Distributed / Cascaded : The type of FTTH architecture where the fiber is spliced ​​from the OLT twice (one in / out of the exchange or one out of the exchange) before the customers arrive at the location. The division can be located in the exchange, FDT, manhole, handhole or FAT.

Feeder : Equivalent to primary cables in copper networks. Fiber cables that connect the exchange to a split point in the FDT or manhole serve as a cross connect to the distribution network.

Distribution : In conventional method of FTTH deployment this is equivalent to the secondary cables in copper network. These are fiber cables that connect the FDT or cross connect cabinet to the final distribution point (a FAT or a splice in a handhole before the drop). In short, we can say that this is the cable between the feeder and the drops.

Drops :  The optical fiber cable from the last distribution point up to customer's location.

CER - Communication Equipment Room : Buildings drop point to house indoor FDT cabinets, FAT and ONT's.

Abbreviation used in Optical Network

AON ➤ Active Optical Network
APON ➤ ATM Passive Optical Network
PON ➤ Passive Optical Network
BPON ➤ Broadband Passive Optical Network
ePON ➤ Ethernet Passive Optical Network
GPON ➤ Gigabit Passive Optical Network
OLT ➤ Optical Line Terminal OLT
ONT ➤ Optical Network Terminal
ONU ➤ Optical Network Unit
ODN ➤ Optical Distribution Network
ODF ➤ Optical Distribution Frame
FTTH ➤ Fiber To The Home
FTTB ➤ Fiber to the building
FDH ➤ Fiber distribution hub
FDT ➤ Fiber distribution Terminal
FAT ➤ Fiber Access terminal
WDM ➤ Wavelength division multiplexer
Gbps ➤ Gigabits per second
Mbps ➤ Megabits per second
RF ➤ Radio Frequency
SFU ➤ Single Family Unit
MDU ➤ Multi Dwelling Unit
NAP ➤ Network Access Point
TDM ➤ Time Division Multiplexing in downstream
TDMA ➤ Time Division Multiple Access in upstream
SO/HO ➤ Small Office/Home Office
POS (Sp) ➤ Passive Optical Splitter
LCP ➤ Local Convergence Point
CER ➤ Communication Equipment Room
HBU ➤ Home Business Unit
EBU ➤ Enterprise Business Unit
I&R ➤ Department of Installation & Repair
PTP (P2P) ➤ Point To Point
P2MP ➤ Point To Multi Point
E2E ➤ End To End
Ne ➤ Network Engineer Tool System

Overview Legacy Copper VS FTTH

Legacy networks designed to deliver a single service efficiently are incapable of offering the desired bundle services and bandwidth.

The telecommunications has reached the stage network. The existing copper network is unable to meet the demand of increase in bandwidth for in residential and business customers for several applications. These demands can only be met by deeper penetration of optical fiber into the access network and increased deployment of fiber-to-the-home (FTTH or FTTP).

Telecom operators has adopted GPON as preferred broadband technology strategically for his FTTH or FTTP project in line with global trends to face the anticipated challenges in terms of band width required for various services in competitive market. The selected technology provides triple play voice, video, and data services over a common protocol (IP) and medium. Operators are increasingly moving to maximize the number of services offered to a single customer through a bundle offering. Technology such as Voice over IP (VOIP), IP television (IPTV), and Broadband (HSI) will become a major need with innovative and value-added services.

Legacy Copper Networks

➤POTS
➤Narrowband Data
➤Limited Broadband not more than 2mbps (Symmetric & Asymmetric).

Active Optical Networks – (AON) 

➤ Fiber Nodes Extended Nearer to the End Users-Active Nodes.
➤ Legacy copper in the last mile – FTTC
➤ Legacy copper/CAT cables in the last mile – FTTB & ETTH
➤ Successfully served the residential, SMEs and corporates by customizing the solution as per customer’s requirement
➤ Used various type of add drop multiplexers to extend bandwidth ranging from E1 – STM16 to potential customers and other carriers.

Passive Optical Networks – (PON)

➤Getting through the various stages such as APON/BPON of evolution till recent past when the technique was standardizing for ultimate technology names as GPON to cater the requirements of bandwidth for the business communities as well as for the masses.

➤Gigabit Passive Optical Network – GPON // The technology of today and future for all types of network in general and Access Network in particular.

Access Network Terminology 

Access Network Evolution