EPONs use a point-to-multipoint topology, in which multiple optical network units (ONUs) share one uplink channel to transmit multimedia traffic to a control element, the optical line terminal (OLT). Hence, to avoid data collision on the shared uplink, ensure a contention-free transmission and so on, medium access control arbitration mechanisms are essential for the successful implementation of EPONs. In this paper, a novel dynamic bandwidth allocation algorithm,
the Integrated Two Classes Dynamic Bandwidth Allocation (ITCDBA), is put forward, in which the multipoint control protocol is used defined in the IEEE802.3ah standard. ITCDBA is a hierarchical allocation scheme which dynamically allocates bandwidth according to the instantaneous demands of ONUs, supporting inter-ONU priority scheduling as well as intra-ONU priority scheduling. The simulation result shows that the system throughput of EPON is improved with
ITCDBA scheme and the drop rate of the traffic with the highest priority is lower than that with Two-layer bandwidth allocation (TLBA) scheme . In a word, ITCDBA not only can allocate bandwidths between end users effectively and fairly, but also can support differentiated services. Besides, the system performance of EPONs with ITCDBA scheme is improved.
Due to its low cost and packet data efficiency, Ethernet has been one of the most influential technologies for Local Area Networks (LAN). Moreover, the 10-Gigabit Ethernet has begun to move Ethernet from the LAN out to encompass the metro area network. The technology features, protocol architecture and the frame format are introduced. In order to realize the logical boundary between the physical layer and the link layer, the protocol of SPI (System Packet Interface) level4 is adopted. A method of realizing the SPI interface of 10-Gigabit Ethernet is put forward and the function block diagram is presented. In order to reduce the power waste of the chip, the parallel algorithm is chosen in the design.
A method for quantitatively analyzing the survivability of EPON access network is presented. The relationship between the survivability of network and the intensity of network damage is obtained. Meanwhile, the comparison of survivability among three kinds of backup of EPON access network is put forward. The simulation result shows that, when the coverage area is the same, the survivability of EPON with Node-Fiber Backup is better than that with Trunk-Fiber Backup, and when the number and distribution of ONU are the same, the survivability of EPON with Bus-Fiber Backup is better than that with Node-Fiber Backup. The result is useful not only for forecasting and evaluating the survivability of EPON access networks, but also for EPON access networks topology design.