By adopting the orthogonal frequency division multiplexing technology, spectrum-sliced elastic optical path networks can offer flexible bandwidth to each connection request and utilize the spectrum resources efficiently. The routing and spectrum assignment (RSA) problems in SLICE networks are solved by using heuristic algorithms in most prior studies and addressed by intelligent algorithms in few investigations. The performance of RSA algorithms can be further improved if we could combine such two types of algorithms. Therefore, we propose three hybrid RSA algorithms: DACE-GMSF, DACE-GLPF, and DACE-GEMkPSF, which are the combination of the heuristic algorithm and coevolution based on distance-adaptive policy. In the proposed algorithms, we first groom the connection requests, then sort the connection requests by using the heuristic algorithm (most subcarriers first, longest path first, and extended most k paths’ slots first), and finally search the approximately optimal solution with the coevolutionary policy. We present a model of the RSA problem by using integral linear programming, and key elements in the proposed algorithms are addressed in detail. Simulations under three topologies show that the proposed hybrid RSA algorithms can save spectrum resources efficiently.
Resilient Packet Ring (RPR) specified by IEEE 802.17 is a new standard for Metropolitan Area Networks (MANs). One of RPR's characteristics is that it can support three priorities traffic in a single datapath, i.e., class A, class B and class C, ranging from high priority to low priority, respectively. Different entities such as shaping, scheduling, fairness, topology and protection coordinate to guarantee the Quality of Service (QoS) for different services. Various pieces of the datapath in RPR are tied together through logical queues, thus we investigate the datapath from the view of logical queues in this paper. With a detailed analysis of the MAC shaping mechanism in RPR, we propose some improvement to achieve better transport performance for RPR's three priorities traffic. Simulation results show that our improvement is efficient.
Specified as a new ITU-T standard, Multiple Services Ring (MSR) proposes the mechanism of multi-service provision over Resilient Packet Ring (RPR). MSR over RPR is a packet based network which is flexible and efficient for burst data transport, but it is vital to MSR providing a good Quality of Service (QoS) for real-time services. ITU-T defined MSR Service Data Unit (SDU) lengths in X.87 for real-time services, such SDU lengths play an important role in QoS provision. Moreover, the impact of the MSR-SDU length on MSR's performance for real-time services has not been addressed.
The characteristics of MSR are first reviewed, and two core concepts in MSR, Tributary and Tributary Cross Connection Relationship (TCCR) are introduced. Accordingly, the MSR protocol model and generic frame format are presented, followed by briefly comparing the similarities and dissimilarities between MSR and ATM. A simulation model is set up for performance evaluation, in which ten nodes are connected to form a ring with STM-64 links and a distance of three kilometers between adjacent nodes. The frame loss ratio, delay, and jitter characteristics are investigated by increasing the load of TDM circuit emulation (TCE) services or changing the MSR-SDU length while keeping the loads of Ethernet B and C tributaries unchanged. Some conclusions are drawn from the simulations made.
An extended layered graph of MPLS over WDM mesh networks is proposed in this paper, in which the label switch path (LSP) with various wavelengths and the limitation of optical transceivers at a routing node are both involved. Label switch paths are classified into different priorities according to each quality of service. The corresponding routing algorithm, differentiating integrated routing algorithm (DIRA), is proposed and studied. The quality of service (QoS) of a label switch path and the optimization of network resources utilization are taken into account comprehensively in DIRA.
A comparison of DIRA with the representative optical routing algorithms via simulation shows that it can reduce the blocking probability of delay-constraint LSP and improve the network throughput.
Conference Committee Involvement (1)
Network Architectures, Management, and Applications