Limited Delay Preemption Based Priority in Differentiated Optical Burst Switching Networks with Small Buffers

The composite scheme based on preemption and small buffers is an efficient method for contention resolution. To support services differentiation, it is the first time that the analytical model of delay preemption based priority is built. Further, in order to guarantee the low-loss requirement for high priority bursts, an improved scheme is proposed and investigated by limiting the buffered right of low priority bursts within the specific traffic states. The simulation results show that, without the deterioration of blocking performance, there is more than 40% reduction on burst loss being achieved under the conditionρ=1.0 for high priority bursts.

A novel data channel fault detection mechanism in optical burst switching networks

Fault detection in optical burst switching （OBS） networks will be a challenging task in the future. A novel mechanism based on probe burst （PB） and a new key concept is proposed to detect faults of OBS networks by sampling the health of data channels, which solve the difficulty of optical monitoring schemes while keeps the transparency of data network to Internet protocol （IP） packets. It takes full advantage of the characteristics of OBS, including architecture and signalling scheme, and introduces the excellent performances of single-hop-test used in electrical communication networks into OBS environment while avoids the shortcoming that any optical burst must undergo an optical-electric-optical （OEO） conversion. Well designed PB can provide exact criterion for judging whether protection/restoration should be excuted according to hard or soft fault identification.

A new burst assembly technique for supporting QoS in optical burst switching networks

This letter proposes a new burst assembly technique for supporting QoS in optical burst switching (OBS) networks. It consists of the adaptive-threshold burst assembly mechanism and QoS-based random offset-time scheme. The assembly mechanism, which is fit well to multi-class burst assembly, not only matches with IP QoS mechanism based on packet classification, and also utilizes fairly and efficiently assembly capacity. Based on token-bucket model and burst segment selective discard (BSSD), the offset-time scheme can smooth the traffic to support OBS QoS. The simulation results show that the technique can improve the performance in terms of packet loss probability (PLP).

A congestion alleviated scheme in optical burst switching network

An optical burst switching （OBS） network platform is established with a ring topology of three nodes. A congestion Mleviated scheme using advanced token protocol and wavelength tunable receivers is demon- strated to optimize the network platform. Experimental results testify that this scheme can resist collision at the level of 0.1% congestion rate.

A QoS-Guanranteed Scheduling Algorithm with High Throughput for Edge Nodes of Optical Burst Switching Networks

A scheduling algorithm for the edge nodes of optical burst switching (OBS) networks is proposed to guarantee the delay requirement of services with different CoS (Class of Service) and provide lower burst loss ratio at the same time. The performance of edge nodes based on the proposed algorithm is presented.

A new prediction method at the edge of optical burst switching network

To achieve lower assembly delay at optical burst switching edge node, this paper proposes an approach called current weight length prediction (CWLP) to improve existing estimate mechanism in burst assembly. CWLP method takes into account the arrived traffic in prediction time adequately. A parameter 'weight' is introduced to make a dynamic tradeoff between the current and past traffic under different offset time. Simulation results show that CWLP can achieve a significant improvement in terms of traffic estimation in various offset time and offered load.

A novel scheme based on minimum delay at the edges for optical burst switching networks

This paper proposes a novel scheme based on minimum delay at the edges (MDE) for optical burst switching (OBS) networks. This scheme is designed to overcome the long delay at the edge nodes of OBS networks. The MDE scheme features simultaneous burst assembly, channel scheduling, and pre-transmission of control packet. It also features estimated setup and explicit release (ESXR) signaling protocol. The MDE scheme can minimize the delay at the edge nodes for data packets, and improve the end-to-end latency performance for OBS networks. In addition, comparing with the conventional scheme, the performances of the MDE scheme are analyzed in this paper.

UNITED STABILIZING SCHEME FOR EDGE DELAY IN OPTICAL BURST SWITCHED NETWORKS

A novel scheme, namely united stabilizing scheme for edge delay, is introduced in optical burst switched networks. In the scheme, the limits of burst length and assembly time are both set according to certain qualifications. For executing the scheme, the conception for unit input bit rate is introduced to improve universality, and the assembly algorithm with a buffer safety space under the self-similar traffic model at each ingress edge router is proposed. Then, the components of burst and packet delay are concluded, and the equations that limits of burst length and assembly time should satisfy to stabilize the burst edge delay under different buffer offered loads are educed. The simulation results show that united stabilizing scheme stabilizes both burst and packet edge delay to a great extent when buffer offered load changes from 0.1 to 1, and the edge delay of burst and packet are near the limit values under larger offered load, respectively.

Research and Progress of Service Driven Optical Switching Network in China

National R&D activities on optical switching networkare introduced. Optical switching network testbedswere established in China including 3T-net andOBS ring and mesh network test-bed with the supportof national '863' program. As an importantmodule in OPS network, a novel all-optical serialmulticast mode is discussed.

A novel optical burst switching architecture for high speed networks

A novel optical burst switching （OBS） high speed network architecture has been proposed. To verify its feasibility and evaluate its performance, just-enough-time （JET） signaling has been considered as a high performance protocol. In the proposed architecture, to avoid burst losses, firstly, a short-prior- confirmation-packet （SPCP） is sent over the control channel that simulates the events that the actual packet will experience. Once SPCP detects a drop at any of the intermediate nodes, the actual packet is not sent but the process repeats. In order to increase network utilization, cost effectiveness and to overcome some limitations of conventional OBS, inherent codes （e.g., orthogonal optical codes （OOC））, which are codified only in intensity, has been used. Through simulations, it shows that a decrease in burst loss probability, cost effectiveness and a gain in processing time are obtained when optical label processing is used as compared with electronic processing.

Performance analysis of an integrated scheme in optical burst switching high-speed networks

A new integrated scheme based on resource-reservation and adaptive network flow routing to alleviate contention in optical burst switching networks is proposed. The objective of the proposed scheme is to reduce the overall burst loss in the network and at the same time to avoid the packet out-of-sequence arrival problem. Simulations are carried out to assess the feasibility of the proposed scheme. Its performance is compared with that of contention resolution schemes based on conventional routing. Through extensive simulations, it is shown that the proposed scheme not only provides significantly better burst loss performance than the basic equal proportion and hop-length based traffic routing algorithms, but also is void of any packet re-orderings.

A novel differentiated services supporting scheme for optical burst switched networks

In this letter, we analyze the drawback of tail-dropping contention resolution in optical burst switched networks. Once contention occurs, we adopt modified head-dropping policy to resolve contention. This policy drops the head of the contending burst only if the overlapping region of the two bursts is less than the whole contending burst size, otherwise drops the whole contending burst. In order to have a better support of differentiated service, a new burst assembly policy, namely, Priority-based proportional mixed burst assembly, is proposed. Simulation results show that the proposed scheme performs very well in terms of performance metrics such as the times of contention and packet loss probability.

Priority-Based Mixed Assembly Supporting Differentiated Service for Optical Burst Switched Networks

In order to have a better support of differentiated service, we propose Priority-based mixed burst assembly, in which packets of different priorities are assembled in a burst with an assigned proportion, and the priorities are lined in an ascending order in a burst from head to tail. Simulation results show that the proposed scheme performs very well in terms of latency and packet loss probability.

用于光突发交换的光模块(特邀)

【目的】为满足人工智能(AI)集群网络对于资源分配的灵活性和资源利用率的高要求,光突发交换(OBS)重回人们的视野。这对光模块提出了更高的要求:首先,纳秒级光路切换速度要求高速光模块的接收侧适应突发模式;其次,目前达到纳秒级的高速光开关普遍存在光路插入损耗大的问题,所以要求高速光模块的光链路损耗达到超长(ER)距离标准。【方法】为满足此需求,文章采用全商用芯片搭建薄膜铌酸锂(TFLN)+光电探测器(PD)方案的ER光模块,设计了测试系统,下一步工作还在进行中。【结果】实验结果表明,此系统光链路预算达到了20 dB,基本满足高速光交换对光模块链路损耗的要求。OBS系统对各种颗粒大小光模块均可以接受,文章初步探讨了3类单波100 Gbit/s光模块的设计:因为存在整机功耗和体积的限制、四波混频(FWM)和多路小光敏面雪崩光电探测器(APD)导致耦合困难等问题,4路光的ER光模块(ER4)实现起来比8路光的ER光模块(ER8)容易很多。两路光的ER2模块可以采用同轴工艺电吸收调制激光器(TO-EML)+APD方案,工艺实现更容易,性价比更高,配套芯片更加成熟。【结论】所以200 Gbit/s ER2是目前OBS的优选品种。

有优先权的光突发交换中光缓存的性能分析

分析了配置有限数量光纤时延线 (FDLs)和优先权机制的光突发交换 (pOBS)网络性能 ,建立了 pOBS的网络模型和排队模型 ;并以模型为基础 ,比较了各级别数据包的排队等延时与FDLs单位、负荷强度比例的关系 ;比较了有和无FDLs时 ,包丢失率与FDLs单位、FDLs深度、系统负荷强度以及波长数的关系 研究发现 ;高优先级数据包的平均延时远小于其它数据包 ,负荷强度越大平均延时也越大 ,高优先级数据包的比例越大则低优先级数据包的延时越大且丢失率越高 ,加入有限数量和适当深度的FDLs、减小FDLs最小单位。

OBS网络中基于优先级与突发包分割的偏射路由机制(英文)

为了有效地降低突发包的丢失率和保证OBS网络中不同优先级业务的服务质量,提出了一种基于优先级与突发包分割的偏射路由机制.当冲突发生时,首先基于突发包的优先级进行"竞争突发包头部分割或者原突发包尾部分割"处理;无冲突部分直接在事先预留的输出数据信道上处理,冲突部分的分割突发包根据参数可调的偏射路由机制被偏射到最佳偏射路径上.仿真结果表明,该机制能够有效地降低整个网络的丢包率和端到端的延时,并且得到高优先级突发包的丢失率和延时低于低优先级突发包.由此可知,基于优先级与突发包分割的偏射路由机制能够有效地解决突发包的冲突问题,从而提高整个OBS网络的性能.

光突发交换网络中多跳公平分割丢弃方法的研究

光突发交换网络被认为是一种新的IPoverWDM网络,也是下一代互联网的发展趋势。该文给出了一个在光突发交换网络中解决多跳分割丢弃不公平性的改进方法,该方法不但保留了原有方法的可以保证多跳网络中数据包丢失率的一致性优点,而且还减小了损失,增大了网络吞吐量。最后通过仿真验证了该方法的有效性,对实际网络的设计有一定的理论指导意义。

光通信网新技术

新技术的开发和使用使得光网络层具有了许多原先只能在高层实现的网络功能 ,并使原先单纯为了增加传输容量的WDM层具有了真正的光联网功能。以光标记交换技术、光突发分组交换技术、无纤光通信系统以及全新的光互联网技术为代表构成了今天的光通信网研究热点并吸引了世界各国科研院所和著名通信公司的广泛关注。

光突发交换网中一种新的有优先权的冲突解决方案

提出了一种解决不同优先级突发包之间资源竞争的方案,分析了该方案下不同优先级的性能(时延和丢包率).研究结果表明高优先级突发包的平均时延和丢包率都远小于低优先级突发包,因此该方案能为高优先级突发包提供很好的QoS保障.

基于圈覆盖的光突发交换网状网故障监测方案

针对光突发交换网状网中采用逐跳探测的故障监测方法监测成本过高的缺陷,提出了基于探测圈覆盖的故障监测机制.该机制利用启发式深度优先搜索(HDFS)、最短路径欧拉匹配(SPEM)和启发式生成树圈覆盖(HST)3种典型的圈发现算法搜索光突发交换网状网的圈覆盖,然后为每个圈安放一个故障探测模块,构成基于圈覆盖的监测机制.计算和统计结果表明,该机制相对于逐跳探测机制能节约大量监测成本.