EPON and GPON are the two main members of optical network access. Each of them has own advantages, competes and complements each other.The following will compare with them in various aspects.

Data Rate

EPON provides a fixed up and downlink with 1.25 Gbps, using 8b/10b line coding, and real rate is 1Gbps.

GPON supports a variety of speed grades, can support uplink and downlink asymmetric rates, downlink 2.5Gbps or 1.25Gbps, uplink 1.25Gbps or 622Mbps, according to actual needs to determine the uplink and downlink rates, select the corresponding optical module, and increase the Cost performance of optical device speed.

Shunt ratio

The shunt ratio is an OLT port with a number of ONU .

The EPON standard defines shunt ratio is 1:32.

The GPON standard definition shunt ratio as follows: 1:32, 1:64; 1:128.

In fact, the EPON system can also achieve higher shunt ratio, such as 1:64, 1 :128, and EPON control protocol can support more ONU.

The shunt ratio is mainly restricted by the performance index of the optical module, and a large shunt ratio will cause a significant increase in the cost of the optical module.

GPON offers multiple options, but the cost advantage are not obvious.

The maximum physical distance supported by GPON system is the maximum transmission distance, When the optical shunt ratio is 1:16, it should support the maximum physical distance of 20km. When the optical shunt ratio is 1:32, it should support the maximum physical distance of 10km.

The EPON is the same, and it's the same thing.

QoS(quality of service）

Ethernet protocol does not handling QoS ability, therefore, in order to make the EPON serve user, the concept of a virtual local area network (VLAN) is proposed. The VLAN proposes that the received frame can be modified. The priority marking lays the foundation for QOS, but VLAN is achieved artificial, so cost is extremely high. And GPON itself has excellent QoS service capability.

GPON has its own excellent QoS service capabilities.

PON and GPON link layer comparison

Compared with GPON, EPON is simpler and more direct. In pure Ethernet transmission, the two packaging methods and ATM support of GPON will not play a major role.

However, in the access network service, EPON is only suitable for data transmission services, while GPON can provide three in-one services.EPON is a kind of the Ethernet solution, fully conforms to the characteristic of Ethernet protoco and performance, and the GPON using synchronous optical network (SONET, synchronous optical network)/synchronous digital hierarchy (SDH, synchronous digital hierarchy) technology and general frame agreement for Ethernet transmission.

Both EPON and GPON have their own advantages, GPON is better than EPON in terms of performance indicators, but EPON have the advantage of the time and cost, GPON is catching up, looking for the future,the broadband access market may not be replaced by anyone, it should be complementary coexist.

For bandwidth and multi-business, QoS, security requirements and ATM technology as a client of backbone network, GPON will be more suitable.

In terms of cost sensitive, QoS and security requirements are not high customer base, EPON becomes dominant.