A packet transport network (PTN) for optical carrier Ethernet needs to be reliable even in a case that a fault occurs on a data path. To survive from the network fault, protection switching which sends data traffic to a pre‐established backup path can be implemented on optical PTN systems. Linear protection switching in a multi‐protocol label switching – transport profile (MPLS‐TP) environment requires to be performed with sub‐50 ms for multiple faults on data paths (i.e. tunnels). The linear protection switching for the recovery from multiple faults at almost ten tunnels can be processed on CPU. In this study, a packet transport layer protection switching integrated circuit (PPSI) is developed to increase the number of multiple protection switchings (e.g. 4000 + tunnels) with satisfying the strict requirement on sub‐50 ms switching time, by processing on a field‐programmable gate array (FPGA). The performance of this FPGA implementation is compared with that of the processed on CPU. Furthermore, this study investigates four message forwarding methods of set‐bridge‐and‐selector and automatic protection coordination protocol messages to enhance the performance of the PPSI. The four methods are evaluated using an FPGA test‐bed, in terms of switching time and the number of tunnels.

Shared mesh protection (SMP) is a protection mechanism that recovers traffic delivery against failures on a working path as rapidly as linear protection. In addition, it allows for resource sharing among the protection paths with different endpoints in a mesh network by coordinating the use of shared resources when multiple protection paths compete for these resources. Owing to limited protection resources and the preemption in consequence of priority comparison, the SMP introduces a new optimization problem whose objective is to find the optimal priority assignment that maximizes the number of protected services against any failure case for a given SMP network. In this paper, we recognize that the problem of finding the optimal solution is NP-hard and propose min-degree and capacity-density approximation algorithms, whose approximation ratios are presented with the maximum degree of services and the maximum capacity of segments of an SMP network. Moreover, we propose a depth-based algorithm that always finds the optimal solution for a hypertree-shaped SMP network. We compare the performance of the proposed algorithms in terms of the protection ratio, which we define in this paper.

This paper models a ring loading problem suited for survivable Ethernet rings blocking a link to create a loop-free topology. When a block is given on a link of an Ethernet ring, loading of traffic demands is immediately determined due to the logically formed bus topology. As the traffic load over a ring varies depending on the position of the block, the ring loading problem can be viewed a new optimization problem named the ring block positioning (RBP) problem. Our RBP is grouped into two types: RBPGto minimize the overall ring load and RBPLto minimize the maximum link load. For each RBP, we present an exhaustive search method to check all block cases on a ring and then suggest a more effective ring loading algorithm ensuring the computing time shorter than the exhaustive search. According to our experiments using MATLAB, each effective ring loading method shows computing time about 360 times in RBPGand about four times in RBPLfaster than each exhaustive search while finding the optimal block to satisfy the goal of each RBP.

Most of current ring-based Ethernet protection schemes work on a basis of filtering database (FDB) flush operation to guarantee data forwarding on protection switching. However, when a link or node failure occurs in a congested ring network, delayed data frames that have lower priorities than control frames can cause the FDB inconsistency problem that ring nodes build incorrect FDB information. Under this circumstance, some of ring nodes forward data frames in the wrong directions, so that the ring network shows undesirable and unstable performance. In order to resolve this problem, this paper introduces the following three techniques: flush delay timer, purge triggering, and priority setting. Especially, for the priority setting scheme we develop an absorbing Markov chain model for the Ethernet Ring Protection (ERP) protocol defined by G.8032. Then, we theoretically estimate the expected protection time on protection switching underlying the M/M/1/k queue system and also suggest an enhanced priority setting method to guarantee reliable protection switching even in a congested network. Along with our theoretical approach, we additionally evaluate the protection performance with a network simulator to verify our mathematical model. Simulation results show that our analytic model is indeed capable of estimating the expected protection switching time.

In this paper, an algorithm that provisions absolute and proportional differentiation of packet delays is proposed with an objective for enhancing quality of service (QoS) in future packet networks. It features an algorithm that compensates the deviation for the prediction on the traffic to be arrived continuously. It predicts the traffic to be arrived at the beginning of a time slot and measures the actual arrived traffic at the end of the time slot. The difference between them is utilized to the delay control operation for the next time slot to offset it. As it compensates the prediction error continuously, it shows superior adaptability to the bursty traffic as well as the exponential rate traffic. It is demonstrated through simulations that the algorithm meets the quantitative delay bounds and shows superiority to the traffic fluctuation in comparison with the conventional non-adaptive mechanism.

In this paper, we present a Contention Aware Transport (CAT) protocol which is hop-by-hop, rate-based control, over IEEE 802.11 MANETs. CAT introduces a novel control metric, Sending Rate Control Factor (SRCF), for the congestion control. The SRCF considers the contention density which represents the degree of contention level experienced at a given node. In addition, to support reliable delivery, CAT uses a hop-by-hop acknowledgement scheme. The main purpose of CAT is, to find optimal traffic load that the channel bandwidth is fully utilized by sending rate adjustment while minimizing the packet losses from medium contention. The simulation results show that the network throughput achieved by CAT is around 10% and about 30% at peak point, higher than that of TCP and TCP-SACK.

Abstract In this paper, we consider a problem in networks with storage servers for providing multimedia service. The design involves assigning communication link capacity, sizing the multimedia servers, and distributing different types of content at each server, while guaranteeing an upper limit on the individual end‐to‐end blocking probability. We consider alternative methods for obtaining the end‐to‐end blocking probability with low computation time and present optimization procedures to obtain an optimal solution. Under a linear cost structure, our numerical investigations consider different scenarios that might be helpful in understanding how to distribute multimedia content for a cost‐optimized solution. © 2001 John Wiley & Sons, Inc.

We consider an optimization problem in networks with storage servers for providing multimedia service. The design involves assigning communication link capacity, sizing the multimedia servers and distributing different types of content at each server, while guaranteeing an upper limit on the individual end-to-end blocking probability. We present optimization algorithms to obtain an optimal solution. Under a linear cost structure, our numerical investigations consider different scenarios that might be helpful in understanding how to distribute multimedia content for a cost-optimized solution.