Signaling-based path-segment protection in mesh optical networks

Path protections have become increasingly important for current mesh optical networks because fast restorations in generalized multiprotocol label switching(GMPLS) networks are uncertain.However,setting up additional disjoint paths to protect connections leads to more path setup blocking and signaling collisions.We analyze signaling collisions,path blocking and blocking probability,as well as calculate node-to-node blocking probabilities.A signaling-based path-segment protection(PSP) is proposed,which integrates segment protections and path protections as well as enhances the performance of path protections and ring protections.The setup of PSP connections causes less blocking probability than the setup of path protection connections in the simulations.     

基于SRLG约束和资源共享的交迭段保护机制研究

通过对共享风险链路组约束机制和交迭段保护机制的分析,将两者相结合并根据工作和保护路径分别采用动态链路权重调整,提出了一种基于共享风险链路组不相关的交迭段共享保护算法.交迭段共享保护算法在共享风险链路组不相关的约束条件下,为整个工作路由提供了多个交迭的保护段,并给出了一种能够合理有效选择这些交迭保护段的方法.对交迭段共享保护算法的分析和仿真结果表明,与以往保护算法相比,交迭段共享保护算法不但大大提高了网络连接的可靠性,而且还通过不同交迭保护段间资源的合理共享,有效地提高了网络资源的利用率.     

Fast restoration scheme for MPLS-TP enabled optical multicast

To improve the restoration performance of a multicast service of multi-protocol label switching transport profile （MPLS-TP） enabled optical network,this letter proposes a local-node initiated fast restoration （LNIFR） scheme for MPLS-TP optical multicast service.The proposed scheme allows the local node to establish a segment of fast loopback label switch path by the local node along the upstream of the failed node or link to the nearest downstream node.The fast restoration of optical multicast trees is realized through this part restoration,which focuses on failed node or link.Simulation analysis and results demonstrate that the new scheme outperforms the other schemes in terms of restoration time and success rate.     

Extending path computation element for lightpath restoration in wavelength-switched optical networks

<正>Current generalized multi-protocol label switching(GMPLS) standards do not include adequate models for wavelength-switched optical networks(WSON) in recovery mechanisms.In this letter,GMPLS/path computation element(PCE) extensions are applied for the restoration of the lightpaths disrupted by collision or optical impairment.A reserved deflection routing scheme is proposed to achieve fast restoration. It uses the expanded PCE component to compute and assign the backup paths for lightpath recovery. Numerical results demonstrate that this scheme is effective and low cost.     

QoS-aware precautionary performance monitoring for PCE-based coherent optical OFDM networks

A quality-of-service(QoS)aware scheme,called precautionary performance monitoring,is proposed to solve the optical impairments and congestion control in coherent optical orthogonal frequency division multiplexed(CO-OFDM)networks.The centralized path computation element(PCE)extensions based on the QoS level are applied to optical performance monitoring in this letter.     

Efficient label distribution mechanism for bidirectional paths in MPLS-TP networks

Transport network paths are typically bidirectional and symmetrical. In multi-protocol label switching (MPLS) and generalized MPLS (GMPLS) mechanisms, independent labels are distributed for bidirectional paths. Thus, the requirement of the MPLS transport profile (MPLS-TP), which is a new transport technology, could not be satisfied efficiently. A novel label distribution mechanism for bidirectional paths in MPLS-TP networks is proposed. Labels distributed by the mechanism are symmetrical and can re?ect the pairing relationship of the forward and backward directions of the transport path.     

Wavelength pre-assignment collision schedule for wavelength-routed optical networks

A novel wavelength assignment scheme called the wavelength pre-assignment collision schedule （WPCS） is proposed for wavelength-routed networks. The WPCS pre-assigns the wavelength at the forward detection phase, and schedules the potential collision by priority. The potential collision is scheduled at the forward detection phase and the blocking of the wavelength assignment is reduced. Simulation is conducted with several other existing schemes. The numerical results show that WPCS performs better than other schemes in blocking probability under various traffic conditions.     

Design of contention resolution over backup path in path computation element based wavelength-switched optical networks

<正>A contention resolution scheme.P-cycle auto-switching(PCAS).is proposed in wavelength-switched optical networks(WSONs) based on generalized multi-protocol label switching(GMPLS) to solve backward blocking.This system permits the preferable request and switches the other to a backup path generated by the P-cycle.Simulation results show that the PCAS scheme is effective in mitigating backward blocking, especially under concentrated load.