Have you heard these two words, GPON and EPON? If you did, did you know their differences?
Before our discussion, we need to know these several letters’ meaning.
GPON means Gigabit Passive Optical Network and EPON means Ethernet Passive Optical Network. Both of them belongs to PON (Passive Optical Network), which is a fiber network that only uses fiber and passive components like splitters and combiners rather than active components like amplifiers, repeaters, or shaping circuits. Such networks cost significantly less than those using active components.
Figure 1: The Types of PON
A PON takes advantage of wavelength division multiplexing (WDM), using one wavelength for downstream traffic and another for upstream traffic on a single mode fiber (ITU-T G.652). BPON, EPON, GEPON, and GPON have the same basic wavelength plan and use the 1490 nanometer (nm) wavelength for downstream traffic and 1310 nm wavelength for upstream traffic. 1550 nm is reserved for optional overlay services, typically RF (analog) video.
So, after knowing PON, we can start to discuss the differences between GPON and EPON.
What is GPON?
GPON (Gigabit Passive Optical Network) is based on the TU-TG.984.x standard for the new generations of broadband passive optical access.
GPON provides the unprecedented high bandwidth downlink rate of up to 2.5 Gbit/s, the asymmetric features better adapt to the broadband data services market.
GPON provides the QoS full business protection, at the same time carries ATM cells and (or) GEM frame, the good service level, the ability to support QoS assurance and service access.
GPON also provides Access Network Level Protection Mechanism and full OAM functions.
GPON is widely deployed in FTTH networks. It can develop into two directions which is 10 GPON and WDM-PON.
Figure 2: Diagram showing a typical GPON network.
What is EPON?
EPON (Ethernet Passive Optical Network) is the rival activity to GPON which uses Ethernet packets instead of ATM cells.
EPON uses 1 gigabit per second upstream and downstream rates. It is a fast Ethernet over PONs which are point to multipoint to the premises (FTTP) or FTTH architecture in which single optical fiber is used to serve multiple premises or users.
EPON is an emerging broadband access technologies, through a single fiber-optic access systems, to access the data, voice and video service, and it has a good economy.
Figure 3: Diagram showing a typical EPON network.
What are the Differences?
In fact, both GPON and EPON deliver Ethernet to the end user. The difference is GPON is a purpose-built point to multi-point transport protocol while EPON conscripts Ethernet to attempt the same inefficiently.
We have found a big surprise: North America EPON shipments packed in 2005 at 20,000. GPON hit 1.2 mil in 2012 and still going…
Doesn’t anyone use EPON? Yes, all EPON solutions are manufactured originally in ASIA so there are some deployments there.
Now in North America, there are financials, hospitals, US Military, Dept Energy, Homeland Security, NSA and Residences are using GPON, not EPON.
In short, we can use a table to compare GPON with EPON.
|Usable Bandwidth||Downstream: 1.25 Gbit/s or 2.5 Gbit/s,Upstream: 155 Mbit/s – 2.5 Gbit/s||1-Gbit/s symmetrical bandwidth|
|L2 Dynamic Rerouting||Yes||No|
|Reach||128 ONUs||32 ONUs per OLT, or 64 FEC|
|Efficiencies of Each Standard||Up To 65,535 Bytes In ATM-Based Pons||Up To 1518 Bytes According To The IEEE 802.3 Protocol For Ethernet|
|Management systems||Not Support Multicast Services||A single management system|
|Support for CATV Overlay||Yes||Yes|
|Encryption||Downstream only||Both downstream and upstream.|
|Network Protection||Vendor-specific and carrier-specific protection||Vendor-specific and carrier-specific protection|
|Popular Area||U.S.||Asia and Europe.|
1. ONUs: Optical Network Units
2. OLT: Optical Line Terminal
3. FEC: Forward Error Correction
4. CATV: Cable Television
Both of GPON and EPON have their own advantages and disadvantages. It’s hard to say which is better. It seems that we will continue to use them in the future.