Using Epon to realize Telecom-grade FTTH scheme

At present, FTTH as a new hotspot technology in the field of broadband access has attracted the attention of operators, among which Epon technology has many advantages such as high maturity and low cost, and becomes the preferred scheme for FTTH. Epon is an important part of IEEE 802.3ah workgroup (ie EFM, First mile Ethernet), the main idea is to apply Ethernet technology on the PON network structure, which makes epon can directly inherit the low cost of widely used Ethernet technology and many other advantages.

For different reasons, people still have more doubts about the use of epon, mainly embodied in two aspects: first, the network structure of Epon is a bit of the tree network structure, there is a single point of failure of the hidden trouble; second, Epon is simple, mature, but may be Ethernet in the QoS, security, OAM and other aspects of the problem into the Access network field. In the practical application, Epon can overcome the above two aspects of the problem and meet the requirements of the telecommunications level?

The industry has long considered the problem of topological structures. The ITU-T g.983.5 Standard, adopted in 2002, provides a detailed bpon protection approach. Since there is no substantial difference in the physical layer of PON technology, this standard is directly referenced as a programmatic document for various PON technology protection following epon. The Epon GB that is being drafted directly adopts the first two protection modes in the g.983.5: the backbone fiber protection switching mode and the fiber full protection switching mode. In the backbone optical fiber protection mode, the main standby pon port of the Olt side is connected to two ports of the 2:n tap respectively, from the tap to the ONU side to adopt the regular connection. The cost of this approach is relatively small, the backbone of epon can protect the fiber, the reliability of the system greatly improved. In the optical fiber full protection switching mode, each ONU achieves a dual-attribution connection with two separate optical taps through two upstream pon ports, each of which is connected to two PON ports of the Olt. This way completely eliminates the epon system single point of failure hidden trouble, but the cost is also the whole double. It can be seen from the above introduction that EPON can achieve a high reliability topology if necessary. Beacon Communication AN5000 Series Epon products fully support the above two protection methods, in the number of already participated in the system test showed a strong reliability.

For the problem of the natural defects of Ethernet in QoS, security and OAM, the industry has put forward a perfect enhancement means to solve epon.

For traditional Ethernet, the means of implementing QoS is 802.1P, and the service classification is realized by assigning different priority to different frames. Many people intuitively believe that 802.1P used in Epon can be a large extent to solve the QoS problem. However, a fundamental problem is: in the Epon system, Olt plays a leading role in allocating system resources, from Epon ONU to Olt, the only criterion that the system does not directly identify and deal with the resources of the 802.1p,olt scheduling system is llid. Obviously, the direct use of 802.1P in Epon can not solve the QoS problem. The Epon system of beacon Communication adopts multi Llid technology, which solves the QoS problem of Epon completely. In the Epon system of beacon Communication, each ONU can allocate multiple llid, each llid can be flexibly configured for different business channel or user channel. In this way, the Ethernet frames carrying different upper-level services are different llid, each llid can get different priority processing, according to the system policy to deal with each traffic bandwidth allocation, delay and jitter constraints and other indicators. It can be foreseen that the EPON system based on multi Llid will show the competitive advantage of the relative single llid system in many aspects such as QoS. It is worth mentioning that, multiple llid is configurable enhancements, by default, in order to facilitate interoperability of many manufacturers, the beacon of Epon products configured as a single llid, when needed can be opened at any time.

Because the downlink data of Epon is realized by broadcasting TDM, there is the possibility of intercepting and receiving by individual users. In this case, our domestic EPON standards force the EPON system to encrypt the downlink data. Beacon Communication AN5000 series Epon products using standard AES-128 encryption algorithm, can effectively protect the user data is not stolen. The reliability of AES-128 is more trustworthy than that of the few in the industry, which adopts churning way to realize the downlink reliability of Epon. In addition, it is worth mentioning that, because the beacon of Epon products support Llid technology, its encryption can be carried out for different llid, more flexible to achieve.

In IEEE 802.3ah, the OAM function of epon is specially stipulated, our national standard has strengthened the requirement of this project. Epon provides a dedicated overhead frame to provide OAM functionality. The basic OAM capabilities of EPON include: self-loop testing, fault monitoring and so on. From the actual needs of operators, these functions completely changed the traditional Ethernet OAM ability of the defect, for epon large-scale into the FTTH field has laid a solid foundation. However, these basic OAM functions specified in the standard do not meet all the requirements of the operator. Beacon Communication Epon products provide the necessary OAM capability while providing the programmable OAM development environment, can provide OAM extension at any time according to the requirements of operator customization.

Through the above analysis, we see some of the confusion in the field of Epon is being solved, whether it is the reliability of the topology or the modification of the inherent defects of Ethernet, the industry has taken a welcome step forward. Among them, the Beacon communication AN5000 series of telecommunications-class architecture system to fully support the Epon line protection function, support Epon QoS, security, OAM and other enhanced design, leading epon into the telecom operators deployment plan. In each FTTH project which has been contracted by the Beacon Communication, the above excellent telecom-grade design features have opened up a new broadband value-added road for operators.