Generalized Multiprotocol Label Switching Networks Research Articles

Multi-Level Buffering Services Based on Optical Packet Encoding of Composite Maximal-Length Sequences in a GMPLS Network

Generalized multi-protocol label-switching (GMPLS) provides packet-switching with multiple speeds and quality-of-services (QoSs). Packet buffering in GMPLS reduces packet loss by resolving the conflicts between packets requesting for a common channel. Presently, due to the diversity of multimedia applications, enabling multiple services in networks has become necessary. In this paper, a family of codes known as composite maximal-length sequence (CMLS) codes is introduced into an optical buffering scheme based on code-switching. A given number of available CMLS codes is divided into several code subsets. The buffer selects an unused CMLS code from a code subset and assigns it to the incoming packet. When all codes in a specific subset have been distributed to the queued packets, a free CMLS code in another subset is chosen for the new arrival. To achieve multi-level buffering services, the partition scenario with a lower subset number but with a higher number of codes in an individual subset is used as a code-assigning method for buffering high-QoS users. A two-level buffering system is demonstrated by examining the QoS of each class in terms of packet-dropping probability (PDP). The results show that different levels of PDPs can be effectively supported by a common buffer architecture.

A Practical Traffic Control Scheme With Load Balancing Based on PCE Architecture

The path computation element (PCE) is used for the path computation for traffic engineering systems such as multi-protocol label switching (MPLS) and Generalized MPLS networks. It offers a good architecture for the centralized traffic routing and control. The classic routing policy aims to select one “best” path for the traffic, which may cause network congestion in the best link. How to adjust traffic to alleviate or avoid congestion is an important issue for operating networks. In this paper, according to the topology and the traffic model of China Telecom’s network, we propose a practical traffic control scheme with load balancing based on the PCE architecture. The objective of the traffic control scheme is twofold. First, an adaptive end-to-end path selection algorithm is proposed to select high-quality main and backup paths with the consideration of cost and path utilization. Second, a global routing optimization algorithm is proposed to adjust the path for the traffic, which considers the congestion feedback, the adjustment cost, and the expectation of load balance. The results show that our proposed scheme is able to efficiently alleviate or avoid congestion problem and achieve good performance in terms of the balance of link utilization and minimum computation time.

Label Stacking Scenarios in Hybrid Wavelength and Code-Switched GMPLS Networks

Multi-protocol label switching (MPLS) is a promising solution to implement high-speed internet protocol (IP) networks by reducing the layer number. To meet the increasing demand for data traffic, optical packet switching (OPS) is integrated under IP to provide high bandwidth to end users. Generalized MPLS (GMPLS) is perfectly compatible with the routing algorithm in IP/MPLS as it supports packet-switching functions. In this paper, we investigate the label stacking scenarios in GMPLS networks. In GMPLS, label stacking is done to reduce the node complexity by appending multiple labels to a single packet. Wavelength-division multiplexing (WDM) and optical code-division multiplexing (OCDM) signals have been widely used as identifying labels. As the labels can be permutated among the wavelengths or code dimensions, the structure of a label stack can be varied. However, studies on the relationship between label stacking scenarios and network performance are limited. To investigate this issue, we propose three label stacking models: sequential code distribution; sequential wavelength distribution, and random label distribution. The simulation results show that the sequential wavelength assignment, wherein the labels are uniformly distributed among the wavelengths, exhibits the best system performance in terms of the label-error rate (LER).

Investigation of Blocking Performance in GMPLS Networks

AbstractThe call blocking is the most vital factor in generalized multiprotocol label switching (GMPLS) Networks. Call blocking depends upon many factors such as traffic intensity, number of servers and number of links. Call blocking performance for GMPLS networks has been calculated in this paper by using a proposed mathematical model. The proposed model investigates the dependency of probability of call blocking upon the number of wavelengths and number of links. In the suggested model, the blocking performance of GMPLS network is improved.

A Review on Deployment Architectures of Path Computation Element using Software Defined Networking Paradigm

In traditional Generalized Multi-Protocol Label Switching (GMPLS), wide variety of functionalities like, GMPLS signaling GMPLS routing and link management increased the computational complexity of a single GMPLS network node. In concern with this, in order to provide the best paths by concerning effective utilization of network resources and better quality of transmission, a dedicated Path Computation Element (PCE) has been introduced. Software Defined Networking (SDN) is a new paradigm that decouples the network control from the data plane. With Software Defined Networking, the design, build and manage of networks can be made cost effective and dynamic manner, by transforming the traditional networks into open and programmable networks. The objective of this paper is to provide different architectural models of path computation element using Software Defined Networking paradigm. Using these deployment models, a network operator can manage and operate both the circuit switching and packet switching networks, thereby reduce capital expenses as well as operational expenses.

Multirate Multiservice All-Optical Code Switched GMPLS Core Network Utilizing Multicode Variable-Weight Optical Code-Division Multiplexing

A multicode variable-weight (MCVW) technique is proposed for generalized multiprotocol label switching (GMPLS) optical networks in order to support multirate and integrated multimedia services. Under this technique, the number of simultaneously assigned codewords to each user is a function of the data rate of the service class, while quality-of-service differentiation is achieved using variable-weight codewords for each service class. The traffic behavior of the network is modeled using a multiservice loss model, and the probability density functions of the number of busy codes in the fiber link are obtained by the Kaufman–Roberts algorithm. In order to analyze the performance of the proposed multiservice multicode GMPLS optical network, several measures are derived and investigated, specifically, the bit-error rate, probability of degradation, blocking probability, and steady-state throughput. These performance measures are obtained for two different receiver structures, namely, correlation receivers with and without hard limiters. The performance of our optical GMPLS network, based on the multicode switching path, is compared with that of traditional optical GMPLS networks, based on the label switching path. The results show the superiority of the proposed technique when compared to traditional ones.

ESTIMACIÓN Y OPTIMIZACIÓN DEL BALANCEO DE CARGA USANDO INGENIERÍA DE TRÁFICO ADAPTATIVA MATE EN REDES DE CONMUTACIÓN DE ETIQUETAS MULTIPROTOCOLO GENERALIZADO (GMPLS)

The article proposes the use of load balancing algorithm with (MATE) adaptive traffic engineering to be used as load distributor through multiple links on Generalized Multiprotocol Label Switching networks (GMPLS). This with the purpose of making more efficient distribution of the existing routes between the origin and destination of the data. The methodology included the algorithm, implemented in C++ to assess their performance in the discrete event simulator NS-2 and from the results generating an optimization proposal that would raise their performance. In can be noted that MATE presents stability problems that were solved by the modeling of adaptive convergence function valid for GMPLS networks.

The GMPLS Controlled Optical Networks as Industry Communication Platform

In this paper, Generalized Multiprotocol Label Switching (GMPLS) controlled optical networks are considered as industry communication network. GMPLS is a Next-Generation Network technology which will be used to build new Internet backbone. Thanks to the features of a new public network, Internet can become a platform for industrial communication including critical data, transactional flow, and real-time data. The benefits of such a network for industry are explained in this paper. Next, the idea and architecture of intelligent, next-generation optical transport networks is discussed and explained. One of the challenges of GMPLS technology is a reliability as the main factor which influences service quality. Therefore, the method of improving reliability of GMPLS is proposed. This method bases on the implementing of redundancy in the control plane. Using Monte Carlo simulation and proposed reliability analysis method quantity improvement of GMPLS network reliability is shown and the merits of using this method are confirmed. Achieved simulation results and analysis confirm also that this emerging optical transport network will offer industry long distance communication with transmission condition compared to what is provided by dedicated WAN links. Simultaneously using public infrastructure can reduce cost of long distance communication.

All-Optical Multiservice Path Switching in Optical Code Switched GMPLS Core Networks

In this paper, we present a novel labeling scheme to provide multiservice path switching in a generalized multiprotocol label switching (GMPLS) network. The idea is based on optical code division multiplexing (OCDM) scheme in GMPLS network using multilength variable-weight optical orthogonal codes(MLVW-OOC) as signature sequences. The router architecture of the proposed multiservice GMPLS network is also presented. To provide a requested service, the length and the weight of codes are designed based on the service characteristics. Furthermore, to guarantee the desired service, we propose to limit the number of connections based on the activity coefficient of the connected paths. In order to analyze the network performance, the end-to-end bit error rate (e - e BER) of a connection and the probability of QoS degradation (Pdeg) are considered as benchmarks. To obtain the e - e BER of the connected path, a closed-form relation describing the BER of the MLVW-OOC-based OCDM system is derived, and the Erlang's model is used to examine the Pdeg. As a case study, a four-class network is designed with the proposed labeling scheme and the performance of each class is investigated. The numerical results reveal that users with high-weight codeword acquire better performance. Furthermore, by increasing the number of intermediate routers, the e - e BER is increased and the performance can be improved by limiting the number of connected paths.

Multiservice Provisioning and Quality of Service Guarantee in WDM Optical Code Switched GMPLS Core Networks

In this paper, we propose a new scheme to provide multiservice transmission on generalized multiprotocol label switching (GMPLS) networks using optical code-division multiplexing (OCDM) in each wavelength of a wavelength-division multiplexing system. To provide multiservice transmission in a typical GMPLS network, we propose to classify the fiber bandwidth into a number of waveband and consider the wavelengths of each waveband for a specific class-of-service such that the corresponding codes to be used are designed based on the characteristics of the class-of-service. The traffic behavior of the network is examined using <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Erlang's</i> <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">model</i> , and the probability density functions (PDF) of the number of occupied labels in a link are obtained. To evaluate the PDF of the number of occupied labels in each wavelength, two scenarios are considered: path establishment without traffic management and path establishment with traffic management. In the first scenario, connected paths are divided among wavelengths randomly; while in the second scenario, a controlling mechanism manages distribution of the connected paths so that all wavelengths have the same number of connected paths. To analyze the performance of the system, end-to-end bit error rate, probability of outage, and blocking probability are investigated. The obtained results reveal that path establishment with traffic management results in better performance. Furthermore, to guarantee the desired quality of service (QoS), a controlling mechanism is proposed to limit the number of connected paths based on the activity coefficient of the connections. We show that using such controlling mechanism the desired QoS is guaranteed.

Layer-preference policies in multi-layer GMPLS networks

We address the problem of routing Label Switched Paths (LSPs) in multi-layer networks based on the Generalized MultiProtocol Label Switching (GMPLS) paradigm. In particular, we pursue policies for choosing the appropriate layer to host a new LSP request, as we find that such layer-preference policies have significant impact on network performance. We discuss several simple layer-preference policies and we reveal why these simple policies ruin network performance in the long run. Consequently, we develop an efficient heuristics, the Min-phys-hop routing and wavelength assignment algorithm, to govern the selection of the best layer of a multi-layer network in which to host new LSP requests. We discuss the applicability of this algorithm with respect to the state-of-the-art GMPLS standards, above all, the GMPLS routing extensions to OSPF-TE. By extensive simulations, we justify that the Min-phys-hop algorithm produces close-to-optimal blocking and resource consumption under almost all possible selections of input parameters, and this is regardless of the wavelength and Optical-Electrical-Optical (OEO) conversion capability present in the network.

Restoration in all-optical GMPLS networks with limited wavelength conversion

A new generation of optical components and the advance of the Generalized Multi-Protocol Label Switching (GMPLS) control plane supporting dynamic provisioning and restoration of optical connections (i.e., lightpaths), brings the vision of the dynamic all-optical network closer to reality. An emerging technology is the conversion between wavelengths, which removes the wavelength continuity constraint, thus allowing an easier and more flexible connection allocation. A limitation in the number of wavelength converters impairs their benefits especially during the restoration phase, when many simultaneous recovery attempts must share residual resources. This paper investigates the restoration performance of GMPLS-controlled all-optical networks with limited wavelength converter deployment. We investigate how different restoration methods, namely span restoration, segment restoration, and end-to-end restoration are affected by the availability of a limited number of wavelength converters at each node. For this purpose an enhanced wavelength assignment scheme compliant with GMPLS signaling is exploited, aiming at saving converters by assigning a higher preference to wavelengths not requiring conversion. An extensive simulation study has been conducted comparing the performance of this scheme to the most advanced scheme based on standard GMPLS signaling for the three restoration methods. Simulation results show that the enhanced wavelength assignment scheme significantly reduces the number of wavelength converters (WCs) necessary to achieve good recovery performance. The enhanced scheme especially improves span restoration performance, where the matching between the stubs' and recovery segment wavelength may require a WC. End-to-end restoration is the least affected, due to a higher degree of freedom in the route choice, while segment restoration performance lies in between.

A Scalable Path Protection Mechanism for Guaranteed Network Reliability Under Multiple Failures

We propose two versions of Link Failure Probability (LFP) based backup resource sharing algorithms, namely LFP based First-Fit algorithm, and LFP based Best-Fit algorithm for Generalized Multi-Protocol Label Switching networks. Customers' availability requirements are met by adjusting the availability of the protection paths with different sharing options. Information required for calculating the availability of both the working, and protection paths can be collected along the specific working, and protection paths, thus avoiding the requirement for flooding. This makes our algorithms scalable for a large network. Our algorithms work consistently against both single, and multiple failures. Furthermore, we propose extensions for the existing signaling protocols to demonstrate that our proposed algorithms require minimum changes to the existing protocols. Simulation results show that our proposal performs better than the conventional Dedicated Path Protection schemes in terms of Call Acceptance Rate, and Total Bandwidth Consumption. Finally, by comparing simulation results to analytical results for a simplified network, we provide some insights into the correctness, and efficiency of our proposed algorithms

Optical CDMA for All-Optical Sub-Wavelength Switching in Core GMPLS Networks

Generalized multi-protocol label switching (GMPLS) is a multipurpose control-plane paradigm that extends the MPLS scheme allowing switching without recognizing packet boundaries. In this paper, we present a novel extension that exploits a new physical layer for switching in optical GMPLS. The proposed extension is achieved through adding an optical code switching layer, or code switch capable (CSC) layer, to the existing label mapping layers. Our proposal enables finer granularity at sub-wavelength level in all-optical GMPLS core switches, resulting in significant enhancements to traffic isolation capabilities for all-optical GMPLS core switches. We employ mathematical analysis to derive performance bounds for the proposed scheme, from both the labeling capacity and network throughput points of view. We use our analytical model to derive several optimum operating points for the network, and show that our techniques significantly improve the overall performance of all-optical core networks

Concurrent Failures and Redundant Protection Problem in Hierarchical GMPLS Networks

The generalized multiprotocol label switching (GMPLS) networks attain a hierarchical structure, andeach layer maintains an independent protection mechanism, resulting in redundant protection. The common pool method provides a basic approach to solve the redundant protection problem. Although the common pool method is simple and robust, however it can fail in some cases. This work first shows that none of the prior work satisfies both redundant protection and two links failure problem simultaneously. Moreover, this work also presents a new type of two links failure problem (i.e., the failure of two links at two different layers), which can happen frequently and the common poolmethod cannot cope with. To solve the proposed two links failure problem, while minimizing the cost of redundant protection problem, this work proposes a new protection scheme for hierarchical GMPLS networks.

Precomputation for Multi-Constrained QoS Routing in GMPLS Networks

Multi-Constrained QoS routing in GMPLS (generalized multiprotocol label switching) network is to find an optimal path satisfying several constraints, such as bandwidth, cost and delay. The problem has been considered as a NP-Complete problem. Based on SRLG heuristic information, the paper provides a MPAS algorithm (Multi-constrained Precomputation Algorithm with SRLG), which includes the precomputation and searching procedures. The precomputation is able to create and update the routing tables in each node. Then, the searching procedure can select an optimal path satisfying several constraints in the hierarchical architecture. The results of extensive simulation based on the self-similar traffic show that the corresponding methods can achieve satisfactory performance and efficiently solve the problem of multi-constrained QoS routing in GMPLS network.

Generalized Traffic Engineering Protocol for Multi-Layer GMPLS Networks

This paper proposes a Generalized Traffic Engineering Protocol (GTEP). GTEP is a protocol that permits communication between a Path Computation Element (PCE) and a Generalized Multi-Protocol Label Switching (GMPLS) controller (CNTL). The latter is hosted by each GMPLS node: it handles GMPLS and MPLS protocols such as routing and signaling protocols as well as controlling the GMPLS node host. The PCE provides multi-layer traffic engineering; it calculates Label Switched Path (LSP) routes and judges whether a new lower-layer LSP should be established. GTEP functions are implemented in both the PCE and GMPLS router. We demonstrate a multi-layer traffic engineering experiment conducted with GTEP.

A novel method for QoS provisioning with protection in GMPLS networks

In this paper, a new optimal policy is introduced to determine, adapt, and protect the Generalized MultiProtocol Label Switching (GMPLS) network topology based on the current traffic load. The Integrated Traffic Engineering (ITE) paradigm provides mechanisms for dynamic addition of physical capacity to optical networks. In the absence of such mechanisms, the rejection of incoming requests may be higher. The objective of the proposed policy is to use ITE to set up virtual tunnels at the MPLS and optical level and protect them against failures. This objective is achieved by minimizing the costs involving bandwidth, switching and signaling. The proposed policy is a computationally non-intensive greedy heuristic with good performance. The new policy operates at two levels: the MPLS network level and the optical network level. Numerical results are presented which show the effectiveness of the policy and the achieved performance.

An Interdomain Path Computation Server for GMPLS Networks

The demand for intra- and interdomain routing for multilayered networks such as those using generalized multiprotocol label switching (GMPLS) is strong. One of the features that is peculiar to GMPLS networks is that because several different domains, such as those of IP, ATM, and optical fiber, are combined with each other hierarchically, various routing policies, which are sometimes independent from underlying domains and sometimes taking the underlying domains' policies into consideration, are required. For example GMPLS's lower layer LSPs like lambda LSP are expected to be established independently before the upper-layer LSPs, like IP and MPLS LSPs, are established in the underlying domains. Another requirement for the GMPLS interdomain routing is lightening the burden for selecting the interdomain route, because there are a lot of demands to interconnect many GMPLS domains. In order to satisfy these demands, we propose a path computation server (PCS) that is special for the intra/interdomain routing of GMPLS networks. As a counterpart of the proposed interdomain routing, it is now becoming popular to apply OSPF to the GMPLS interdomain routing. Therefore, we compared the proposed interdomain routing with OSPF, and show the applicability of the routing to GMPLS networks.

Scalable Multi-Layer GMPLS Networks Based on Hierarchical Cloud-Routers

This paper proposes the hierarchical cloud-router network (HCRN) to overcome the scalability limit in a multi-layer generalized multi-protocol label switching (GMPLS) network. We define a group of nodes as a virtual node, called the cloud-router (CR). A CR consists of several nodes or lower-level CRs. A CR is modeled as a multiple switching capability (SC) node when it includes more than one kind of SC, which is fiber SC, lambda SC, time-division multiplexing (TDM) SC, packet SC, even if there are no actual multiple switching capability nodes in the CR. The CR advertises its abstracted CR internal structure, which is abstracted link state information inside the CR. A large-scale, multi-layer network can then achieve scalability by advertising the CR internal structure throughout the whole network. In this scheme, the ends of a link connecting two CRs are defined as interfaces of the CRs. We adopt the CR internal cost scheme between CR interfaces to abstract the network. This CR internal cost is advertised outside the CR via the interfaces. Our performance evaluation has shown that HCRN can handle a larger number of nodes than a normal GMPLS network. It can also bear more frequent network topology changes than a normal GMPLS network.