Improving Network Availability—A Design Perspective

Computer Networks

Cellular networks are nowadays considered as a major critical infrastructure. Resiliency to failure due to disasters, weather based disruptions or malicious activities is essential. In the case of ring topology, because of delay and availability requirements, a wireless network connected to an aggregation node must sometimes be split into several rings. In this paper, we study the availability optimization in a ring-based network topology for a given number of cellular sites and a given size of rings. We prove that if each ring includes 3 nodes, the problem can be solved in a polynomial time, while for bigger rings, the problem is NP-hard. In this latter case, we provide approximation methods based on linear programming in order to converge to the solution.

Computer Communications and Networks, 2020

Traditional approaches to provide classes of resilient service take the physical network availability as an input and then deploy redundancy and restoration techniques at various layers, often without full knowledge of mappings between layers. This makes it hard (and often inefficient) to ensure the high availability required by critical services which are typically a small fraction of the total traffic. Here, the innovative technique of embedding a higher availability sub-structure, designated the spine, into the network at the physical layer, is explored. In the spine-based approach, it is considered that high availability must begin at the physical level, and then must be reinforced in upper layers. A recent disaster resilience framework, named FRAmework for DIsaster Resilience, which incorporates reliable network design (i.e., using the spine), disaster failure modelling and protection routing to improve the availability of critical services is discussed. Next, a proposal to select network links for availability upgrade to ensure high availability is presented. This is followed by a study assuming that if disaster-prone areas are known, they can be represented as obstacles which should be avoided when deploying the physical backbone of a communications network. Hence, a heuristic for a minimum cost Euclidean Steiner tree taking into account the presence of soft obstacles is presented.

Global Telecommunications Conference, . GLOBECOM . IEEE, 2001

This paper addresses the spare capacity allocation (SCA) problem considering any single node failure in mesh networks. The SCA node failure problem aims at finding backup routes and providing sufficient spare capacity to protect traffic when any single node fails in a communication network. Here, we introduce our novel matrix formulation of the arc-flow SCA node failure model. In this

2014 6th International Workshop on Reliable Networks Design and Modeling (RNDM), 2014

In data communication networks, connection availability, which is defined as the probability that the corresponding connection will be found in the operating state, is a key element of many Service Level Agreements (SLA). The path over which a connection is to be established should obey the agreed-upon availability, otherwise the service provider may face revenue loss as stipulated in the SLA. In this paper, we study the problem of establishing a connection over at most k (partially) link-disjoint paths for which the availability is no less than δ (0 < δ ≤ 1). We consider networks with and without Shared-Risk Link Groups (SRLGs). We prove that this problem, in general, cannot be approximated in polynomial time, unless P=NP. We subsequently propose a polynomial-time heuristic algorithm and an exact Integer Nonlinear Programming (INLP) formulation for availability-based path selection. Finally, the proposed algorithms and two existing heuristic algorithms are compared in terms of acceptance ratio and running time.

2016 12th International Conference on the Design of Reliable Communication Networks (DRCN), 2016

2008

Link dimensioning and routing problems in resilient network design are considered. Reliable network operation is ensured by means of flow restoration which is performed on preselected protection (backup) paths that can absorb traffic overflows from failed primary paths. Backup and primary flows use separated link capacities, and can be split among many paths. In the paper, two restoration models are considered. The first model assumes that once the backup path is assigned it must be used in every state in which the protected primary path fails while the second model allows different protection paths to be used in different network failure states. The problems are formulated as multiple commodity linear programming (LP) models using the link-path (L-P) notation and solved by the column generation technique. Consequent pricing models and algorithms are introduced. Computational efficiency of the presented approaches is analyzed.

2014

In data communication networks, connection availability, which is defined as the probability that the corresponding connection will be found in the operating state, is a key element of many Service Level Agreements (SLA). The path over which a connection is to be established should obey the agreed-upon availability, otherwise the service provider may face revenue loss as stipulated in the SLA. In this paper, we study the problem of establishing a connection over at most k (partially) link-disjoint paths for which the availability is no less than δ (0 < δ ≤ 1). We consider networks with and without Shared-Risk Link Groups (SRLGs). We prove that this problem, in general, cannot be approximated in polynomial time, unless P=NP. We subsequently propose a polynomial-time heuristic algorithm and an exact Integer Nonlinear Programming (INLP) formulation for availability-based path selection. Finally, the proposed algorithms and two existing heuristic algorithms are compared in terms of acceptance ratio and running time.

Topological optimization of networks is a complex multi-constraint and multi-criterion optimisation problem in many real world fields (telecommunications, elec tricity distribution etc.). This paper describes an heuristic algorithm using Binary Decisions Diagrams (BDD) to solve the reliable communication network design problem (RCND) (2) (4). The aim is to design a communication network topology with minimal cost that satisfies a given reliability constraint. We assum e that a set of perfectly reliable nodes and their topology are given, along with a set of possible communication links that connect them. Each link has a known reliability and is assigned a cost. The relevant relia bility metric is all-terminal network reliability defined as the probability that the network is still connecte d even if some links fail. A trade-off between the investments in the network and the quality of service provided to the users must be found. Both the RCND problem and the network reliability comp...

2013

A telecommunication network is said survivable if it is still able to provide service after one of its components fails. In the late 90’s the concept of p-cycles appeared as a promising alternative to previous technologies (mesh and ring). A p-cycle provides one protection path for a failed span it crosses and it also protects spans that have both end nodes on the cycle but are not themselves on the cycle. P-cycle based networks gather the best characteristics of both mesh and ring based topologies: restoration speed and efficient use of spare capacity. The objective of the Spare Capacity Allocation problem (SCA) is to protect all the traffic of a network with p-cycles, minimizing the total cost. Here we propose a new ILP model for SCA that does not require a priori candidate cycle enumeration. Results improved those of previous models.

— Wireless sensor networks (WSNs) are important for monitoring most of the distributed remote environments. Nodes fault detection is one of the key technologies involved in WSNs, is indispensable in most WSN applications. The distributed fault detection scheme checks out the failed nodes by exchanging data and mutually testing among neighbor nodes in this network The fault detection accuracy of a scheme would decrease rapidly when the number of neighbor nodes to be diagnosed is small and the node's failure ratio is high. An improved scheme is proposed by defining new detection criteria. Simulation process demonstrate that the improved scheme performs well in the above situation and the fault detection accuracy can be increased greatly. wireless sensor-actor networks, sensors probe their surroundings and forward their data to actor nodes. The Actors respond collaboratively to achieve predefined application mission. Since the actors have to coordinate their operation, a strongly connected network topology is necessary to maintain at all times. Also, the length of the inter-actor communication paths maybe constrained to meet latency requirement. Cost-Aware SEcure Routing (CASER) is a protocol to address these two conflicting issues through two adjustable parameters: energy balance control (EBC) and probabilistic-based random walking. CASER has an excellent routing performance in terms of energy balance and routing path distribution for routing path security. A non-uniform energy deployment scheme is also proposed to maximize the sensor network lifetime. Our analysis and simulation will show that we can increase the lifetime and the number of messages that can be delivered under them on-uniform energy deployment by more than four times. CASER has flexibility to support multiple routing. The main objective to have a network which gives assurance of packet delivery and give the node time to regain is that it will be able to carry further load Packets on the network. This can be done by using shortest path. Multi-hop-based schemes often impose high node repositioning overhead and the repaired inter-actor topology using two-hop schemes may differ significantly from its prefailure status.