What’s the Difference between GPON and EPON?

Explanation and Function GPON provides an efficient means of transmission for Ethernet and TDM. As for the lowest cost business, the need for a Layer 2 protocol is Ethernet. Why not choose EPON? We will discuss the differences between GPON and EPON in the following and it is these differences that make GPON become technology choices to the large operators’ deployment.GPONEPON A good starting point for discussion of GPON and EPON on access network is making a brief review toward their mission statement sponsored by agencies. Based on the following observations, IEEE promotes EFM Study Group to realize the Ethernet as an access technology: 1. Supports users to access to the network topology: point to multipoint fiber transmission; point to point fiber transmission; point to point copper transmission. 2. Offers a range of physical layer specifications: 1000BASE-X Extended temperature range of optical components; 1000BASE-X≥10km, a single-mode fiber (SM fiber); PON physical layer, ≥10km, 1000Mbps, single-mode fiber, ≥1: 16; Single voice grade copper for no load on the physical layer. 3. Distance ≥2500ft, speed ≥10Mbps; support user access to the remote network OAM; remote fault indication; remote loopback; link status monitoring.

Comparison GPON only standardized to the line OA&M. In most cases the management of ONT and the service provided by ONT is usually supported by SNMP, thus generating the problem of management and interoperability. In addition, as the object being managed is not in accordance with the needs of the service provider, so, ONT often lack of some key O&M features such as line testing and other fault isolation tools. There is no inherent security measures to EPON: no encryption on link layer. Since the ONT can deceive downlink LAN address and communication, security is further decreased. These risks can be bypassed by adding encryption on some EPON transfer layer, but this will complicate the network or application, and when the application must be taken in different ways with the end position different, it will run a timer as a unified Ethernet protocol. GPON provided protection or redundancy options for access network, and high-end business services often need such service characteristics. Most importantly, GPON has a comprehensive support, including interoperability from different vendors between the OLT and ONT. This greatly reduces the risk of service providers on the requirements of mixing and matching ONT and OLT, and by making new entrants provide a solution for the existing network rapidly, thereby reducing the entrance of innovation. The requirements of the light layer between GPON and EPON is different, because the downlink rate of GPON is 2.5Gbps while the line rate of EPON is only 1.25Gbps. However, as the link of 2.5G is a pair of continuous link transmitter/receiver, and is similar with the mass-produced SONET OC-48 (SDH’ STM-16), so there is no extra cost on it. As for the Uplink rate terms, GPON and EPON nearly the same, and for the 1.2Gbps line rate, the cost of them is the same. EPON may need a little bit extra costs, since it does not support power classification, that is to say, the operating range of the receiver in a burst mode on EPON will be more than GPON. Although the cost of GPON and EPON transmitter/receiver is the same, the GPON will have advantages on the budget of optical link +3 dB compared with EPON. And the 3dB may extend 10km of the fiber distance, or support twice number of GPON ONT on the same GPON OLT, greatly reduced the equipment costs of CO.

Comparison From rural to urban, GPON is widely used in telecom density and urbanization range, the higher line speed and efficiency, and the split ratio of it, the higher flexibility it provides. The optical budget of GPON is more suitable for common long-range loop in North American. The selection of GPON line speed makes it optimized for performance and cost.

Comparison Different bandwidth gains will affect the split ratio allowed by each technology in different ways, and be subject to different OLT port number/the average throughput. Now we will set an example to let you know clearly about the comparison between EPON and GPON. Assuming the existence of a FTTH network has 10,000 service users. Neither speculate the type of service (Internet access, VOIP, using MPEG-2 or -4 standardized IPTV, as well as SDTV or HDTV), nor speculate the number of services per household, we just consider the average throughput of Ethernet-based services into the home. Due to the technology cost roughly the same, we can also assume the equipment cost roughly the same, so we can make the following assumptions:

Comparison Benefits of each technology bandwidth

Advantages The higher GPON line speed will support more services or achieve more surplus income. Moreover, the support to the TDM over GEM has provided a safe alternative for the transmission of traditional business TDM over GEM to provide.

Conclusion Now we can use the result to calculate the average cost/user of each technology according to average throughput. The significant cost advantage of GPON is the decrease of the required OLT numbers. That is to say, GPON adoption will be cheaper compared with EPON solutions, and moreover, it will help operators to bring other cost savings, such as space, but the most important is power consumption and heat dissipation.