Friday, March 6, 2009


EPON (Ethernet Passive Optical Networks) or GEPON (Gigabit Ethernet Passive Optical Networks), also known as Ethernet PON is an IEEE/EFM standard for using Ethernet for packet data, as defined in IEEE 802.3ah. It defines how Ethernet can be transmitted over new media types and in our context point to multipoint fiber.

EPON/GEPON is a fast Ethernet over passive optical networks which are point to multipoint fiber to the premises (FTTP)/fiber to the home (FTTH) architecture in which single optical fiber is used to serve multiple premises or users. A ‘PON’ architecture consists of an Optical Line Termination (OLT) on the provider’s side and one or many Optical Network Units (ONU) on the users’ side. This type of architecture is always better than the point to point ones. These are fast replacing existing technologies as DSL or cable modems as EPON/GEPON are capable of providing bandwidths of up to 1 gigabit and beyond and also serve multiple purposes at a time.

GEPON or EPON has been deployed widely in Japan and provides for a symmetrical 1.0 Gbps data rate in both directions, upstream and downstream and is fast gaining momentum across the globe for obvious advantages for both providers and users alike. GEPON’s biggest advantage is its use of native Ethernet protocols. Also the economics of scale associated with Ethernet components such as optical interfaces, adds to it.

GEPON or EPON provides seamless connectivity for any type of IP-based or other packetized (Ethernet) communications as it employs a single Layer 2 network that uses IP to carry data, voice, and video. Since Ethernet devices are present everywhere from home network to regional, national and worldwide backbone networks, implementation of EPONs has proved to be cost-effective. Also it provides secure communication as encryption is provided in both ends i.e. upstream and downstream, so the chances of eavesdropping fade away. As the transfer rates in Ethernet scale up by the day the scalability of EPON/GEPON is limitless and so is the flexibility of ADNET GEPON devices where we have a variety of products to choose from.

Of the many advantages to offer some are worth to notice, With the GEPON/EPON standard, there is no limit on the number of ONUs, remember these are the units on the users’ side.

GEPON/EPON requires a single management system, which means GEPON/EPON results in a significantly lower total cost of ownership. EPON also does not require multi-protocol conversions. 

Wednesday, March 4, 2009

FTTx Network Basics

The FTTx architecture consists of a passive optical network (PON) that allows several customers to share the same connection, without any active components (i.e., components that generate or transform light through optical-electrical-optical conversion).

A feeder fiber is brought from an optical line terminal (
OLT) in the CO to a fiber distribution hub (FDH) near a group of customers. From that point, a passive splitter is used to typically connect up to 32 or 64 customers to the same feeder fiber. Then, each customer premises is provided with an optical network terminal (ONT) connected to each splitter branch. This point-to-multipoint architecture dramatically reduces network installation, management, and maintenance costs as shown by the figure below.

The OLT provides voice and data downstream transmission using a 1490-nm wavelength band, while the ONT provides upstream transmission with a 1310-nm wavelength band, allowing for bidirectional transmission on the same fiber without the signals interfering with one another.

In addition, the OLT may be connected to a wavelength-division multiplexing (WDM) coupler to provide video together with voice and data (triple-play) services over a single fiber. The video is provided in the downstream direction only, usually in a 1550-nm wavelength band (traditional analog video).