Overview of PON Network

PON has now became a popular network technology all over the globe. It first came in to being in 1995. The International Telecommunication Union (ITU) standardized two initial generations of PON — APON and BPON. And the advancement of PON network has never stopped. Until now, the recent PON standard of NG-PON2 has been put forward in 2015. With the maturity of PON, people are more easily accessible to networks today. But what does PON exactly mean?

 What’s the composition of PON network? The following part will give you the answer.

PON, also known as passive optical network, is a technology in telecommunication that implements a point-to-multipoint (P2MP) architecture. Unpowered fiber optic splitters are used to enable a single optical fiber to serve multiple end-points such as customers instead of providing individual fibers between the central office (hub) and customer. According to different terminations of PON, the network system can be divided into fiber-to-the-home (FTTH), fiber-to-the-curb (FTTC), fiber-to-the-curb (FTTB), etc. To be specific, a PON is made up of an optical line terminal (OLT) at the service provider’s hub and a number of optical network units (ONUs) or optical network terminals (ONTs) near end users. And “passive” is just used to describe that no power requirement or active electronic component is included for transmitting signals in the system.

Types of PON Network

Here are some types of PON that have been used throughout the years:

1) APON

Its full name is asynchronous transfer mode (ATM) passive optical network. As the original PON system, APON uses ATM technology to transfer data in packets or cells of a fixed size. In APON, downstream transmission is a continuous ATM stream at a bit rate of 155 Mbps or 622 Mbps. Upstream transmission is in the form of bursts of ATM cells at 155 Mbps.

2) BPON

BPON, also known as broadband PON, is the improved version of APON. It adopts wavelength division multiplexing (WDM) for downstream transmission with the transmission rate up to 622 Mbps. It also provides multiple broadband services such as ATM, Ethernet access and video distribution. Today, BPON is more popular than APON.

3) EPON

EPON or Ethernet PON uses the Ethernet packets instead of ATM cells. Upstream and downstream rates of EPON are able to achieve up to 10 Gbps. It is now widely applied to FTTP or FTTH architecture to serve multiple users. With the advantages of scalability, simplicity, multicast convenience and capability of providing full service access, many Asian areas adopt EPON for their networks.

4) GPON

Gigabit PON is the development of BPON. It supports various transmission rates with the same protocol. The maximum data rate of downstream is 2.5 Gbps and upstream is 1.25 Gbps. It is also widely used for FTTH networks. But compared with EPON, its burst sizes and physical layer overhead are smaller.

Advantages of PON

• Low cost, simple maintenance, flexible extensibility and easy to upgrade. And no need for power during transmission saves a lot for long-term management.
• Using pure media network avoids the interference of lightning and electromagnetism. Thus PON network is suitable for areas under harsh conditions.
• Low occupancy of central office resources, low initial investment and high rate of return.
• As the P2MP network, PON is able to provide a large range of service to plenty of users.

Conclusion

PON network is for sure an effective solution for multiple network users. EPON and GPON are the most commonly deployed PON systems at present. Since people have been seeking for higher bandwidth provisioning, the capability of transmission will be greatly improved in the near future.

HTFuture aim to be your Reliable Partner for different kinds of Compatible transceiver (QSFP28, QSFP+, SFP, XFP, SFP+ etc) | OTN optical transmission system|DWDM Mux Demux|OADM | OTU | EDFA | NMS | DCM | OLP | OBP etc| More information, welcome to contact Ivy, contact Ivy. Email: sales6@htfuture.com Skype: live:sales6_1683

HTFuture team are ready and happy to assist you.

EPON vs GPON Standard

EPON, based on Ethernet technology, is compliant with the IEEE 802.3ah (mid-2004) Ethernet in the First Mile standard that is now merged into the IEEE Standard 802.3–2005. It is a solution for the “first mile” optical access network. While GPON, or Gigabit PON, is expected to prevail as a leading optical access technology and to eliminate the bandwidth bottleneck in the last mile. Its requirements were set to force by the Full-Service Access Network (FASN) group, which was later adopted by ITU-T as the G.984.x standards.

EPON vs GPON Data Rate

In EPON, both downstream and upstream line rates are 1.25 Gbps, but due to the 8B/10B line encoding, the bit rate for data transmission is 1 Gbps. GPON, on the other hand, supports an asymmetrical data rate of 1.25 Gbps in both streams, as well as a data rate of 2.5 Gbps in downstream and a data rate of 1.25 Gbps in upstream. Hence GPON is better than EPON in this aspect. The following table has a brief comparison of GPON and EPON technology in the PON upstream and downstream bandwidth, bandwidth efficiency and the transmission.

EPON vs GPON Layering

Besides the above characteristics, perhaps the most striking distinction between the two protocols is a marked difference in the architectural approach, especially in layering. The image below will help you to figure it out.

In EPON, Ethernet frames are carried in their native format on the PON, which greatly simplifies the layering model and the associated management. EPON employs a single layer that uses IP (Internet Protocol) to carry data, voice, and video.

GPON, on the other hand, supports two layers of encapsulation. First, TDM (Time Division Multiplexing) and Ethernet frames are wrapped into GEM (GPON Encapsulation Mode) frames, which have a GFP-like format (derived from Generic Frame Procedure ITU G.7401). Secondly, ATM (Asynchronous Transfer Mode) and GEM frames are both encapsulated into GTC (GPON Transmission Convergence) frames that are finally transported over the PON.

The main purpose of the GEM frame is to provide a frame-oriented service, as an alternative to ATM, in order to efficiently accommodate Ethernet and TDM frames. With GEM, all traffic is mapped across the GPON network using a variant of SONET/SDH GFP. GEM supports a native transport of voice, video, and data without an added ATM or IP encapsulation layer. That’s why GPON supports downstream rates as high as 2.5 Gbps and upstream rates from 155 Mbps to 2.5 Gbps. It is much faster than EPON. However, EPON clearly offers a much simpler and more straightforward solution than GPON. The support of ATM and the double encapsulation of GPON serve no real benefit over a pure Ethernet transport scheme.

Cost Comparison

The use of EPON allows carriers to eliminate complex and expensive ATM and Sonet elements and to simplify their networks, thereby lowering costs to subscribers. Currently, EPON equipment costs are approximately 10 percent of the costs of GPON equipment, and EPON equipment is rapidly becoming cost competitive with VDSL.

Summary

It is hard to say GPON is better than EPON, or vice verse. They each have their merits and demerits. When it comes to certain IP/Ethernet services, EPON is more suitable and cost-effective. While GPON has its own advantages in higher bandwidth, faster transmission rate and supporting triple-play services. Until now, EPON is still the mainstream of PON, especially in the Asian countries, but GPON is expanding quickly lately.

If need more information, feel free contact Ivy from HTFuture: sales6@htfuture.com, HTFuture team are ready and happy to assist you.