In this paper, we propose an approach of user traffic segregation, which uses a dedicated logical link identified by LLID to deliver specific service. Illustration and testing are given to show that providing multiple logical links per ONU is more flexible and scalable, comparing with single logical link per ONU cooperating with IEEE 802.Q/p VLAN.
With the need of more and more high quality services, EPON system is widely favored by most people with its advanced technology of Gigabit and PON, which will replace the traditional techniques of copper and MC gradually. We can realize the MPCP protocol defined in IEEE802.3ah by the hardware scheme, such as FPGA or ASIC. Using SNMP protocol to achieve network management is the popular way. SNMP network manager can perform the long-distance configuration of the parameters in EPON system by sending out SET message; on the other hand, it can research the information by sending out GET message. Consequently, the Nios embedded processor acts as a transmission channel or a bridge between SNMP agent and hardware system. Now SOPC is a popular design method, which processes flexible design mode, reducible, expansible, upgradeable, and have the programmable function between hardware and software synchronously in a single chip. Integrated with the advantages of SOC, PLD, and FPGA, SOPC is provided with the following basic characteristics: an embedded processor core; on-chip high speed RAM resources with small capability; processor debug interface and FPGA programmable interface, etc. The Nios embedded processor is a soft core CPU optimized for programmable logic and SOPC (System-on-a-programmable-chip) designs, which accomplishes the data collection and configuration between SNMP agent and hardware system, the report of registration and alarm information, also the fulfillment of DBA which can be operated with all kind of algorithms. SOPC builder is a tool employed as turning out a system based on bus, thereby many components are included in this design, for instance, CPU, memory interface, peripherals interface etc. Developing applications using the Nios embedded processor is slightly different from the traditional processors, since the designer can configure the processor architecture and specify the peripheral content. That is, a designer can build a microcontroller according to system design requirement, as opposed to selecting a pre-built microcontroller with a fixed set of peripherals, on-chip memory, and external interfaces. In this paper, we introduce an EPON system by way of FPGA, and a SOPC design on the basis of Nios platform is given, in which data transmission channel and DBA functions are achieved. According to the need of EPON system, CPU, memory, and peripheral interfaces are selected from the library of SOPC builder. Once the Nios system is created, it may optionally be combined with other used-defined logic. Designer writes the source code, compiles the application software, and debugs the code to meet the need of EPON system.
Keywords: EPON, Nios, SNMP, SOPC, DBA
Proc. SPIE. 5626, Network Architectures, Management, and Applications II
KEYWORDS: Lithium, Light emitting diodes, Fiber to the x, Remote sensing, Networks, Passive optical networks, Telecommunications, Local area networks, Broadband telecommunications, Standards development
Ethernet Passive Optical Network (EPON), which represents the convergence of low-cost Ethernet equipment and reliable fiber infrastructure, appears to be the best candidate for the next-generation broadband access network. A coin has two sides. Although EPON inherits the benefits of Ethernet, it also suffers some disadvantages. With its origin as a LAN technology, where “best effort” delivery and 99.96% uptime were acceptable, Ethernet was never considered to be a candidate for achieving “carrier-class” status, mainly because lack of powerful OAM capabilities. That’s to say OAM function is essential to carrier-class EPON. In this study, the principals of EPON and OAM, together with the necessity of OAM, are presented firstly. Besides, different ways to provide OAM in ITU-T APON, GPON are analyzed respectively. Three means to obtain EPON OAM, using MAC Control Frame, Physical Link Service Overhead Coding Sublayer (PLSOCS) and Reconciliation Sublayer (RS) Preamble are proposed in detail. Moreover, the main functions, such as remote failure indication, remote loop-back, link monitoring and variable retrieval are studied subsequently. After that, the concrete implementation of OAM in EPON is addressed, combining with hardware and software. As a result, an effective way to carry out EPON OAM can be easily drawn.
A newly broadband access technology comes into being with the combination of IP and access technique, which is considered as EPON (Ethernet passive optical network). EPON system resolves the limitation of point-to-point, instead uses the topology architecture of point-to-multipoint. It extends the fiber cable to the last mile, so we can get the end-to-end network system with high efficiency, well expansibility and low maintenance cost. There are many key techniques and problems in EPON system, for example, CDR (Clock and data recovery), RTT (Round-Trip Time), DBA (Dynamic Bandwidth Allocation) and ULSLE (Upper-Layer Shared LAN Emulation). The essential character of MPCP (Multi-Point Control Protocol) used in EPON is to schedule the transmission of the upstream data packets, and to avoid data collision. A central counter is applied to synchronize the upstream data through a time-stamp flag. A REPORT control frame is transmitted, which give the length of the different priority queues. On receiving this control frame, central office device modifies the bandwidth allocation in the grant table. The function relating to the ULSLE protocol is similar with IEEE802.1D Bridge, and also includes point-to-multipoint, therefore so many problems are resolved, such as the frame reflection, the communication among different ONUs.