As one of the most promising next-generation access network （EPON） should pay more attention to its quality of service （QoS）, techniques, the user-oriented Ethernet passive optical network However, now the EPON adopts mostly differentiated services model （Diffserv） that only provides quality control on traffic aggregation, whereas, the quality of user session cannot be guaranteed when the network is overloaded with substantial connections. This article proposes to apply integrated services model （Intserv） in Diffserv-based EPON, which uses per-flow processing to guarantee QoS. In the simulation, a framework of combined Diffserv and Intserv model is employed in an EPON system, with a dynamic bandwidth allocation algorithm that adapts to it. The simulation results demonstrate that the EPON system with the combined models can provide more flexible, various control for user-oriented service quality.
Real-time variable bit rate（VBR） video is expected to take a significant portion of multimedia applications.However,plentiful challenges to VBR video service provision have been raised for its characteristic of high traffic abruptness.To support multi-user real-time VBR video transmission with high bandwidth utilization and satisfied quality of service（QoS）,this article proposes a practical dynamic bandwidth management scheme.This scheme forecasts future media rate of VBR video by employing time-domain adaptive linear predictor and using media delivery index（MDI） as both QoS measurement and complementary management reference.In addition,to support multi-user application,an adjustment priorities classified strategy is also put forward.Finally,a test-bed based on this management scheme is established.The experimental results demonstrate that the scheme proposed in this article is efficient with bandwidth utilization increased by 20%-60% compared to a fixed service rate and QoS guaranteed.
In this article,the problem of load balance in hierarchical routing network is studied.Since conventional shortest path first（SPF） algorithm over aggregated topology in hierarchical routing network may result in worse routing performance,a traffic sharing path selection algorithm and a variable weight scheme are put forward for hierarchical routing network,which can equilibrate the utilities of link resources and reduce the blocking probability of connections with the improvement on survivability.Simulations are conducted to evaluate proposed variable weight and traffics balance（VWTB） algorithm,which combines traffic sharing and variable weight.From the simulation results,it can be found that the proposed VWTB algorithm can balance the traffics and equilibrate the utilities of link resources significantly.
The newly developed multi-protocol label switching transport profile （MPLS-TP） fails to actively alarm the fault in advance when conducting restoration in network, or to avoid the false-alarm when equipped with the active-fault-alarm （AFA） to support carrier-grade reliability. In order to solve this problem, a new AFA based pre-restoration mechanism （AFABPRM） is proposed for MPLS-TP controlled optical network, along with the three levels quality-of-service （QoS） based shortest path first rerouting algorithm （TQ-SPF） in this article. The AFABPRM takes full advantage of the AFA technologies, and can solve the false-alarm problem. Analytical and experimental results suggest the better performances of the new mechanism when compared restoration mechanism with or without AFA function, and show that the AFABPRM can solve the false-alarm problem efficiently.
BAI Hui-feng, LU Yue-ming, JI Yue-feng Key Laboratory of Information Photonics and Optical Communications, Ministry of Education, Beijing University of Posts and Telecommunications, Beijing 100876, China
In recent years, 10 Gbit/s Ethemet passive optical networks （10G EPON） have been gaining considerable interests because of its high bandwidth capability. To ensure smooth transition from 1 Gbit/s to 10 Gbit/s equipment and to avoid a significant one-time investment into such a cost-sensitive market, coexistence of gigabit Ethernet passive optical networks （GEPON） and 10G EPON system are necessary. In this article, coexistence system architecture and a novel bandwidth allocation algorithm called weight-optimized dynamic bandwidth allocation for coexistence EPON （WOCE-DBA） for the system is proposed. The simulation results show that this algorithm can guarantee fair bandwidth sharing among different optical network unit （ONU） groups, without ignoring the inter-ONU and intra-ONU fairness. Most importantly, it can flexibly adapt to the system composition variations and save efforts needed to modify the bandwidth scheduling mechanism during the migration process from GEPON to 10G EPON.
