Multiprotocol Label Switching Networks Research Articles

Preserving Confidentiality in PCE-based Multi-domain Networks

The path computation element (PCE) architecture has been proposed to effectively enable multi-domain traffic engineering (TE) in generalized multiprotocol label switching (GMPLS) networks while providing an adequate level of confidentiality among domains. However, a malicious utilization of the procedures defined within the PCE architecture might affect the confidentiality of network domain information in a multi-domain multi-carrier network scenario. This paper discusses the critical issues of the PCE architecture in terms of confidentiality. A two-step authorization scheme, named the behavior-based PCE authorization policy (BPAP), is proposed. The BPAP includes a novel add-on PCE component and a central authorization policy server to protect against confidentiality breaking. The scheme is based on the PCE protocol (PCEP) client behavior analysis and includes attack pattern detection procedures and possible partial information filtering of the reply message. The applicability of the BPAP scheme is validated in wavelength switched optical networks (WSONs) through simulations focusing on the exchange of a restricted set of available resources. Finally, a BPAP implementation is experimentally evaluated, showing the efficiency of the two-step scheme in terms of scalability, capability to limit the discovery of critical information, and reactivity to confidential attacks.

Performance analysis of data transmissions in MPLS and non-MPLS networks

Basic Network transactions specifies that datagram from source to destination is routed through numerous routers and paths depending on the available free and uncongested paths which results in the transmission route being too long, thus incurring greater delay, jitter, congestionand reduced throughput. One of the major problems of packet switched networks is the cell delay variation or jitter. This cell delay variation is due to the queuing delay depending on the applied loading conditions. The effect of delay, jitter accumulation due to the number of nodes along transmission routes and dropped packets adds further complexity to multimedia traffic because there is no guarantee that each traffic stream will be delivered according to its own jitter constraints therefore there is the need to analyze the effects of jitter. IP routers enable a single path for the transmission of all packets. On the other hand, Multi-Protocol LabelSwitching (MPLS) allows separation of packet forwarding and routing characteristics to enable packets to use the appropriate routes and also optimize and control the behavior of transmission paths. Thus correcting some of the shortfalls associated with IP routing. Therefore MPLS hasbeen utilized in the analysis for effective transmission through the various networks. This paper analyzes the effect of delay, congestion, interference, jitter and packet loss in the transmission of signals from source to destination. In effect the impact of link failures, repair paths in the variousphysical topologies namely bus, star, mesh and hybrid topologies are all analyzed based on standard network conditions.

A REAL-TIME MULTIMEDIA APPLICATION STUDY IN LMDS NETWORKS USING MPLS

Several wireless networking solutions have been developed to provide different types of services for various end user applications. Due to the success of ATM and IP technology in the information technology area. Local Multipoint Distribution Service (LMDS) is a broadband wireless access (BWA) networking solution. In this paper, an LMDS (Local Multipoint Distribution System) over MPLS (Multi-Protocol Label Switching) network for real-time multimedia applications is introduced. LMDS-MPLS network model is realized and simulated by using OPNET 9.0 simulation package. The simulation results are obtained for sample voice, video, data and non-critical data traffics under varying network load conditions. Analysis of the end-to-end delay results is also presented.

Proposed Optimal LSP Selection Method in MPLS Networks

Multi-Protocol Label Switching (MPLS) had been deployed by many data networking service providers including the next-generation mobile backhaul networks, because of its undeniable potential in terms of virtual private network (VPN) management, traffic engineering, etc. In MPLS networks, IP packets are transmitted along a Label Switched Path (LSP) established between edge nodes. To improve the efficiency of resource use in MPLS networks, it is essential to utilize the LSPs efficiently. This paper proposes a method of selecting the optimal LSP pair from among multiple LSP pairs which are established between the same pair of edge nodes, on the assumption that both the upward and downward LSPs are established as a pair (both-way operation). It is supposed that both upward and downward bandwidths are allocated simultaneously in the selected LSP pair for each service request. It is demonstrated by simulation evaluations that the proposal method could reduce the total amount of the bandwidth required by up to 15% compared with the conventional selection method. The proposed method can also reuse the know-how and management tools in many existing networks which are based on both-way operation.

网状光网络中基于信令的路径段保护方法

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.

Solving GMPLS Multi-Region Path Constraints

In this letter, we propose a novel binary integer program (BIP) to obtain the optimal and correct combination of switch type per link, and adaptation capabilities per node, along a multi-region traffic engineered label switched path (TE-LSP) in a generalized multiprotocol label switching (GMPLS) network. The proposed BIP considers constraints such as the nesting/un-nesting order of LSPs, the adaptation capacity per node, the bandwidth capacity per link, as well as efficiency. By efficiency constraint we refer to opting primarily for nesting/un-nesting as opposed to conversion which is a resource demanding process. Numerical results show that applying the proposed BIP in a constraint shortest path first (CSPF) algorithm achieves lower blockage rates and outperforms an existing graph transformation method which is the closest related work to our proposal.

Analysis of crosstalk and modeling of possible number of routing stages for optically transparent wavelength-division multiplexing nodes of generalized multiprotocol label-switched networks

Crosstalk and power penalty analysis for optical code-switched static wavelength routing wavelength-division multiplexing nodes of a generalized multiprotocol label switched (GMPLS) network is presented. The performance of the system is analyzed for coherent crosstalk, end-to-end bit error rate, and the code length. We introduce a new approach to estimate the blocking probability in crosstalk-impaired GMPLS networks. Packet error rate is estimated for an increasing traffic condition. A well-known Erlang's traffic model is used to examine the performance of the system.

Rendezvous Multicast: A Novel Architecture for MPLS QoS Multicast

IP multicast and MPLS (multi-protocol label switching) are proposed to support emerging network applications effectively, extending current IP routing and switching mode in different ways. It is still in progress to combine IP multicast with MPLS properly. In this paper, a novel architecture, called Rendezvous MPLS Multicast, is proposed to support IP multicast in MPLS networks and to have the scalability of multicast routing, to achieve the label space reduction, and to solve some practical problems in implementation. A two-layered structure of control plane without multicast routing protocols is implemented by overlaying novel service control plane over the existing routing control plane to support multicast state aggregate. The interface between the two planes is formulated to support the interaction and cooperation. Moreover, the label distribution process for MPLS P2MP (point to multi-point) connection, with RSVP-TE (resource reservation protocol-traffic engineering) protocol, is extended to support aggregate of multiple label switching paths with traffic engineering and guarantee of quality of service. An algorithm of selecting Rendezvous Routers for Rendezvous MPLS Multicast has been presented. A test-bed with Linux-based implementations of MPLS multicast router and IP multicast service control system has also been constructed. The experimental results show its efficiency in terms of label space reduction and multicast traffic balancing, with the whole system adapting to the dynamic change of group members and network topology.

QoS Routing in Diffserv MPLS Networks

With the emergence of new network applications and quality of service (QoS) requirements, current Internet technology that supports best-effort service is clearly insufficient. This paper undertakes a detailed study of dynamic quality of service routing in Differentiated Service (DiffServ) Multiprotocol Label Switching (MPLS) networks. A polynomial time, heuristic dynamic routing algorithm, namely TE-QOSPF-Mix, is proposed to provide a better trade-off between hop-count and bandwidth optimization. The algorithm uses well-defined comparative function in path selection with computational complexity equals the original Dijkstra’s algorithm. A simulator, UMJaNetSim, is built to simulate and evaluate the proposed algorithm. The simulation results indicate that the proposed QoS routing algorithm exhibits better bandwidth acceptance and lower packet loss ratio.

Comparison Study of Transmission Control Protocol and User Datagram Protocol Behavior over Multi-Protocol Label Switching Networks in Case of Failures

Problem statement: In only a few years, Multi-Protocol Label Switching (MPLS) has evolved from an exotic technology to a mainstream tool used by service providers to create revenue-generating services. MPLS provides a high reliable Label Switched Path (LSP). MPLS failures may degrade the reliability of the MPLS networks. Approach: For that reason, many studies have been conducted to keep the high reliability and survivability of the MPLS networks. Unlike User Datagram Protocol (UDP), Transmission Control Protocol does not perform well in case of like-failure of MPLS networks because of its inability to distinguish packet loss due to link-failure. After the recovery time, TCP takes longer time than UDP to continue as it was before the failure. Results: In terms of packet loss, TCP performs better than UDP. However, the receiving rate of the TCP traffic is much worse than UDP traffic. A need for a mechanism to improve the behavior of TCP after a link failure is needed. This study focused on comparing the behavior of different types TCP as well as UDP traffic over MPLS networks in case of link, node or congestion failures. Conclusion: Although extensions of RSVP-TE protocol support fast recovery mechanism of MPLS networks, the behavior of TCP will be affected during recovery time much more than with UDP.

Redirection based recovery for MPLS network systems

To provide a reliable backbone network, fault tolerance should be considered in the network design. For a multiprotocol label switching (MPLS) based backbone network, the fault-tolerant issue focuses on how to protect the traffic of a label switched paths (LSP) against node and link failures. In IETF, two well-known recovery mechanisms (protection switching and rerouting) have been proposed. To further enhance the fault-tolerant performance of the two recovery mechanisms, the proposed approach utilizes the failure-free LSPs to transmit the traffic of the failed LSP (the affected traffic). To avoid affecting the original traffic of each failure-free LSP, the proposed approach applies the solution of the minimum cost flow to determine the amount of affected traffic to be transmitted by each failure-free LSP. For transmitting the affected traffic along a failure-free working LSP, IP tunneling technique is used. We also propose a permission token scheme to solve the packet disorder problem. Finally, simulation experiments are performed to show the effectiveness of the proposed approach.

Optical Packet Switching Networks With Binary Multiwavelength Labels

We propose a network structure for routing optical packets based on binary multiwavelength labels. We resolve the main drawbacks of previously proposed optical label switching scenarios: high splitting loss and complex, expensive hardware. In our scheme, the label is mapped bit-by-bit to a selection of wavelength bins. Variable-length packets are self-forwarded via a multistage switch. This structure is scalable, high-speed, simple, practical, and low-cost, exploiting the workhorses of today's optical communications systems: arrayed waveguide gratings, distributed feedback lasers, LiNbO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> switches, and low-speed photodiodes and electronics (~ 100 MHz). We also propose a solution to alleviate the sophisticated label swapping processing required in generalized multiprotocol label switching (GMPLS) networks. We time-multiplex the binary multiwavelength labels for the entire optical label switching path. We examine the performance of both schemes experimentally by verifying successful routing and error-free transmission.

End-to-end quality of service constrained routing and admission control for MPLS networks

Multiprotocol label switching (MPLS) networks require dynamic flow admission control to guarantee end-to-end quality of service (QoS) for each Internet protocol (IP) traffic flow. In this paper, we propose to tackle the joint routing and admission control problem for the IP traffic flows in MPLS networks without rerouting already admitted flows. We propose two mathematical programming models for this problem. The first model includes end-to-end delay constraints and the second one, end-to-end packet loss constraints. These end-to-end QoS constraints are imposed not only for the new traffic flow, but also for all already admitted flows in the network. The objective function of both models is to minimize the end-to-end delay for the new flow. Numerical results show that considering end-to-end delay (or packet loss) constraints for all flows has a small impact on the flow blocking rate. Moreover, we reduces significantly the mean end-to-end delay (or the mean packet loss rate) and the proposed approach is able to make its decision within 250 msec.

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.

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.

Performance analysis of non-preemptive GE/G/1 priority queueing of LER system with bulk arrivals

M X / G / 1 non-preemptive priority queue with bulk arrivals has already been analysed in many papers. Two problems are known in this area: first, when the number of priorities is greater than 2, the analysis for priority processes is obviously very difficult to handle. Therefore, the earlier work on the subject was restricted mostly to two priority classes; and second, although analytically explicit results are available, they require sophisticated closed-form expressions of the mean queue length. One particular bulk size distribution – the GE distribution – is motivated by an ME (Maximum Entropy) formulation for the behavior of a G/G/1 queue. The choice of a GE distribution is motivated by the fact that measurements of actual inter-arrival traffic or service times may be generally limited and so only few parameters, such as mean and variance, can be computed reliably. Thus this paper we can obtain very simple and analytic closed-form expression for the mean queue length of a GE/G/1 priority queue and a significant increase in performance evaluation has been achieved. We present the four-class priority queues, performance analysis and simulation of the LER (Label Edge Router) system in the ATM-based MPLS (Multiprotocol Label Switching) network. We wish to obtain the boundary conditions of the mean queue lengths and the mean queueing delays for each priority class, since this metric is one of the most important in performance evaluation parameters for improving QoS and system performance of the LER system in ATM-based MPLS network. A significant numerical example is presented and discussed as well. In order to obtain optimizing the performance analysis for EF flow, AF 1 flow, AF 2 flow and BE flow, the optimum ratios of COV (Coefficient of Variation) can be found via many numerical experiments carried out by the authors for queueing network model with HOL (Head of Line) priority rules. However, the ratios of COV value constraints exist. Furthermore, we find that each service class gradually begins to deteriorate when SQVs (Squared Coefficient of Variations), C ai 2 > 15.524 , C si 2 > 12.96 and traffic intensity is greater than 0.95. We also find the values of maximum allowed burst size for EF flow and AF 1 flow and perform necessary policing actions on EF flow and AF 1 flow at the boundary node of the network. Finally, the four-class GE/G/1 priority queues and performance analysis of the LER system are shown accurate and robust after the comparison between theoretical evaluates and computer simulation results.

Hierarchical multiobjective routing in Multiprotocol Label Switching networks with two service classes: a heuristic solution

AbstractModern multiservice network routing functionalities have to deal with multiple, heterogeneous and multifaceted Quality of Service (QoS) requirements. A heuristic approach devised to find “good” solutions to a hierarchical multiobjective alternative routing optimization problem in Multiprotocol Label Switching networks with two service classes (and different types of traffic flows in each class), namely QoS and Best Effort services, formulated within a hierarchical network‐wide optimization framework, is presented. This heuristic solution is based on a bi‐objective constrained shortest path model and is applied to a test network used in a benchmarking case study. An experimental study based on analytic and discrete event simulation results is presented, allowing for an assessment of the quality of results obtained with this new heuristic solution for various traffic matrices. A dynamic version of the routing method is formulated and its performance with the same case study network is analysed.

MPLS security: an approach for unicast and multicast environments

Multi-Protocol Label Switching (MPLS) network architecture does not protect the confidentiality of data transmitted. This paper proposes a mechanism to enhance the security in MPLS networks by using multi-path routing combined with a modified (k, n) threshold secret sharing scheme. An Internet Protocol (IP) packet entering MPLS ingress router can be partitioned into n shadow (share) packets, which are then assigned to maximally node disjoint paths across the MPLS network. The egress router at the end will be able to reconstruct the original IP packet if it receives any k share packets. The attacker must therefore tap at least k paths to be able to reconstruct the original IP packet that is being transmitted, while receiving k − 1 or less of share packets makes it hard or even impossible to reconstruct the original IP packet. In this paper, we consider the multicast case in addition to the unicast. To our best knowledge, no work has been published for MPLS multicast security. We have implemented our model and measured its time complexity on variable packets size.

A novel path protection scheme for MPLS networks using multi-path routing

Multi-protocol label switching (MPLS) is an evolving network technology that is used to provide traffic engineering (TE) and high speed networking. Internet service providers, which support MPLS technology, are increasingly demanded to provide high quality of service (QoS) guarantees. One of the aspects of QoS is fault tolerance. It is defined as the property of a system to continue operating in the event of failure of some of its parts. Fault tolerance techniques are very useful to maintain the survivability of the network by recovering from failure within acceptable delay and minimum packet loss while efficiently utilizing network resources. In this paper, we propose a novel approach for fault tolerance in MPLS networks. Our approach uses a modified (k, n) threshold sharing scheme with multi-path routing. An IP packet entering MPLS network is partitioned into n MPLS packets, which are assigned to node/link disjoint LSPs across the MPLS network. Receiving MPLS packets from k out of n LSPs are sufficient to reconstruct the original IP packet. The approach introduces no packet loss and no recovery delay while requiring reasonable redundant bandwidth. In addition, it can easily handle single and multiple path failures.

A Novel Mechanism in MPLS Network under Adversarial Uncertainty

The advantage of multi-protocol label switching (MPLS) is its capability to route the packets through explicit paths. But the nodes in the paths may be possibly attacked by the adversarial uncertainty. Aiming at this problem in MPLS Network, in this paper, we propose a novel mechanism in MPLS network under adversar-ial uncertainty, making use of the theory of artificial intelligence, at first, we find the initialized label switching paths (LSPs) using the A* arithmetic, and secondly, during the process of data transmission, we switch the transmission path duly by taking advantage of the non-monotone reasoning mechanism. Com-pared to the traditional route mechanism, the experimental results show that it improves the security if data transmission remarkably under our novel mechanism in MPLS network.