First of all, what is PON
PON (passive optical network) technology (including EPON, GPON) is the main implementation technology for the development of FTTx, which can save backbone fiber resources and network levels, and can provide two-way high bandwidth capabilities under long-distance transmission conditions. The types of access services are rich, and its remote management capabilities and passive optical distribution network structure can greatly reduce operation and maintenance costs, and can support a variety of application scenarios.
PON technology development
Since the emergence of PON, it has been developing for many years, forming a series of concepts, specifications and product sequences such as APON, BPON, EPON, and GPON.
ATM is a cell-based transmission protocol. 155Mb/s PON system technical specifications, ITU-TG.983 series standards;
The APON standard was later strengthened to support a transmission rate of 622Mb/s, and functions such as dynamic bandwidth allocation and protection were added.
Fiber Access Technology
What is EPON?
EPON (Ethernet Passive Optical Network) is a kind of point-to-multipoint network structure, passive optical fiber transmission mode, based on high-speed Ethernet platform and TDM (time division multiplexing) time division MAC media access control mode, providing multiple integrated service broadband access technology.
The EPON system uses WDM technology to realize single-fiber bidirectional transmission.
What is GPON?
GPON (Gigabit Passive Optical Network) technology is the latest generation broadband passive optical integrated access standard based on the ITU-TG.984.x (International Telecommunication Union TG.984.x) standard. With high bandwidth, high efficiency, large coverage, rich user interface and many other advantages, it is regarded by most operators as an ideal technology for achieving broadband and comprehensive transformation of access network services.
GPON networking mode
GPON mainly adopts three networking modes: FTTH/O, FTTB+LAN and FTTB+DSL.
a. FTTH/O is fiber to the home/office. After the optical fiber enters the splitter, it is directly connected to the user’s ONU. An ONU is only used by one user, with high bandwidth and high cost, and is generally aimed at high-end users and commercial users.
b. FTTB+LAN uses fiber to reach the building, and then connects different services to multiple users through a large-capacity ONU (called MDU). Therefore, multiple users share the bandwidth resources of one ONU, and each person occupies low bandwidth and low cost. , Generally aimed at low-end residential and low-end commercial users.
c. FTTB+ADSL uses fiber to reach the building, and then uses ADSL to connect services to multiple users, and multiple users share an ONU. The bandwidth, cost, and customer base are similar to those of FTTB+LAN.
GPON and EPON technology comparison
In view of the different characteristics of GPON and EPON technologies, the following analysis can be made for these two technologies:
1. GPON supports a variety of rate levels, and can support asymmetric upstream and downstream rates. GPON has greater leeway in the selection of optical components, which can reduce costs.
2. EPON only supports ODN levels of Class A and B, while GPON can support Class A, B and C, so GPON can support up to 128 split ratio and up to 20km transmission distance.
3. Compare only from the agreement, because the EPON standard is based on the 802.3 system structure, compared with the GPON standard, its protocol layering is simpler and the system implementation is easier.
4. ITU has followed many concepts of the APON standard G.983 in the process of formulating the GPON standard, which is more complete than the EPON standard formulated by EFM. The provision of a highly efficient TC layer mechanism will become a key point for the ITU in formulating GPON standards.
5. The GPON standard stipulates that the TC sublayer can adopt two encapsulation methods, ATM and GFP. The GFP encapsulation method is suitable for carrying IP/PPP and other packet-based high-level protocols.
Post time: 2021-01-28