Economical protection in MPLS networks

Today the Internet has serious problems of an explosive increase of traffic caused by increased numbers of users. These problems degrade prominently the quality of service (QoS), and make it difficult to provide multimedia and real time services. Various technologies are proposed to solve these problems. Especially, MPLS (multiprotocol label switching) was developed for the Internet backbone network. The faults occurring in high-speed networks such as MPLS may cause massive data loss and degrade QoS. To deliver a reliable service, however, MPLS requires a set of procedures to provide a suitable protection for the traffic carried on the label switched paths (LSPs). This paper proposes an enhanced scheme for fast rerouting to preassigned LSPs in case of LSP or link failures. In order to minimize back-up resources, it allows possibility of splitting traffic of faulty LSP onto available alternative LSPs for fault recovery. We use preassigned LSPs for restoration when fault occurs. Total traffic throughput and resource utilization can be maximized if the traffic of faulty LSP is split over multiple pre-assigned LSPs. In this paper a new approach to providing fault tolerance in MPLS networks using case-based reasoning as a method to find out the amount of traffic forwarded on each pre-assigned LSP based on past experiences if loading process is presented. The pre-assigned LSPs and the percentage of traffic splitting are calculated off-line based on desired QoS and capacity constraints.

Mapping between two heterogeneous networks, Multi Protocol Label Switching (MPLS) and IEEE 802.11e is choice of future technology as it has ability to perform traffic engineering and create the corresponds between LSP (Label Switch Path) and AC (Access Category). This paper discusses the mapping between IEEE 802.11 MPLS integration to achieve quality of service on MPLS networks. MPLS and 802.11e is very useful approach for today’s internet to ensure the Quality of service the end to end. It talks about different approaches to map 802.11e Access Categories (AC) to Label Switched Path (LSP) and their advantages. It then introduces the concept of encapsulated LSPs to achieve future QoS, which requires further study to examine its practicability.

In multi-protocol label switching (MPLS) networks, traffic demands can be routed along tunnels called label switched paths (LSPs). One tunnel is characterized by a path in the network and a reserved bandwidth. These tunnels can be created and deleted dynamically, depending on traffic demand arrivals or departures. After several operations of this type, the network resources utilization can be unsatisfactory, with for instance congestion or too long routing paths. One way to improve it is to reroute tunnels. Different rerouting procedures may be applied, breaking tunnels or using make-before-break. This has to be adapted to the LSP quality of service (QoS) requirements. Moreover, for network management purposes, we would like to control the number of rerouting operations to perform. A global rerouting framework is proposed, which enables to consider independently each class of LSPs. Then, a mathematical model is introduced. As it appears very hard to solve to optimality, a heuristic based on randomized rounding is proposed. Finally, the designed tool has enabled a numerical study on the proportion of tunnels to reroute in order to reach near-optimal network states.

This paper deals with the problem of reroute sequence planning for label switched paths (LSPs) in multiprotocol label switching (MPLS) networks. This problem arises when the path set is recalculated by a global optimization method for achieving a better resource utilization. In this case we have to find a sequence of the one-by-one reconfiguration of the LSPs from their original paths to the optimized paths, with the constraint that the link capacities should not be violated at any time during the reroute process. The problem is computationally hard in real-world situations because of the large amount of routers and LSPs in the network, so that neither exact nor approximation algorithms have practical relevance. We introduce a number of heuristic approaches, which are investigated through extensive empirical tests based on real network topologies. The results reveal the complexity of the problem. We propose possible solutions and suggest future research directions for alternative answers to the reroute sequence planning.

This paper presents a study on traffic management for transporting progressive video streams over multiprotocol label switching (MPLS) networks. Based on the variety of MPLS service models, a unique multi-stream video transport scheme is proposed. A 3-D subband video coder is used in generating the source data traffic. A special feature of this video coder is that the coded bit stream can be easily segmented into sub-streams with different quality of service (QoS) requirements. After source coding and segmentation, multiple streams are formed. Upon their entering into the network, they are labeled with different forwarding equivalence classes (FECs). Specific label switch paths (LSPs) are selected by the MPLS protocols to achieve the desired quality levels. The proposed scheme is studied under the metrics such as the end-to-end video delivery quality, the bandwidth consumption and the pricing of the service. Extensive simulations have been conducted in this study, and some of the results are presented in this paper.

Multi-Protocol Label Switching (MPLS) can efficiently support the explicit routes setup by the use of Label Switched Paths (LSPs) between an ingress Label Switched Router (LSR) and an egress LSR. Hence it is possible to distribute the network traffic among several paths to achieve load balancing, thus improving the network utilization, and minimizing the congestion. The packet-level traffic characteristics in the Internet is so complex that it is natural to do traffic engineering (TE) and control at the flow level. The emerging Multi-Protocol Label Switching (MPLS) has introduced an attractive solution to TE in IP networks. The main objective of this paper is to balance traffic at the flow level among the parallel Label Switched Paths (LSPs) in MPLS networks. We introduce a multipath load-balancing model at the flow level. In this model, each LSP is modeled as an M/G/1 processor-sharing queue. The load-balancing problem is then considered as an optimization problem. Based on the analysis of the model, we propose a heuristic but efficient mechanism that can make good use of the traffic characteristics at the flow level. Packet disorder is avoided effectively by dispatching packets belonging to one flow to the same path. This mechanism only need to be implemented in the ingress LSRs and the egress LSRs, while the intermediate LSRs only forward the packets. Apart from discussing the traffic allocation granularity, and the implementation issues in details, we have also performed extensive simulations using NS-2 with MPLS modules. The simulation results show that the load through the network is well balanced so that the network throughput is improved and the delay is decreased efficiently.

An essential solution is available in Multi-protocol label switching (MPLS), which solve the problems faced by present-day networks: speed, scalability, quality-of-service (QoS) management, and traffic engineering. This paper is an extension of work on Fuzzy based Packet Scheduling Algorithm (FPSA) combined with Packets Processing Algorithm (PPA) in an Internet Protocol/Multi-Protocol Label Switching (IP/MPLS) networks. This will make provision for an intelligent service to the Label Switched Path (LSP) in MPLS networks. Several research work have been proposed on the MPLS Traffic Engineering. However, it is still imperative to further research on the effect of bandwidth increment on the core network using different mechanisms such as the analytical model of MPLS, expert-based packet scheduling algorithm for MPLS QoS support. Since MPLS is not able to provide intelligent routing, it is necessary to propose an intelligent expert system of FPSA combined with PPA. And analytical model of packet forwarding in the MPLS network would be given to provide suitable solution to traffic congestion and reliable services. Furthermore, the network model created using Network Simulator (NS 2), which carries non-real time application such as File Transfer Protocol (FTP) with bandwidth variations. The results obtained from trace files are interpreted by AWK script and used for the further analysis.

This paper proposes the multiprotocol label switching (MPLS)-based hierarchical Mobile IP architecture to allow frequent and seamless location management It proposes that the label distribution protocol (LDP) can be applied to set up the label switched path (LSP) tunnels between the mobile agents (that is, foreign agents and home agents). It means that the IP-in-IP tunnels can be replaced by one or multiple LSP on the MPLS network. When a mobile node (MN) migrates to the adjacent subnet, it performs a regional registration and partial LSP re-establishment method. So our scheme can reduce LSP setup latency more than the existing integration of Mobile IP and MPLS. We also propose a multicast re-routing scheme to support smooth handover on the MPLS-based hierarchical Mobile IP network after analyzing several LSP re-routing schemes.

This paper presents a new bandwidth management framework supporting Differentiated Services aware Traffic Engineering (DSTE) in the Multi-Protocol Label Switching (MPLS). Our bandwidth management framework contains route computation, bandwidth allocation and preemption for Label Switched Paths (LSPs). We put forward two algorithms. The first one, named bandwidth preemption algorithm, dedicated for the Maximum Allocation Model and in which preemption is conducted in two dimensions: Class Type and priority levels within a same CT. Furthermore, we design a second algorithm named LSP preemption algorithm to select the most appropriate LSPs to be cast out. Selection decision is made on the basis of several citeria: the precedence level, the number of LSPs to preempt and the excess of bandwidth to gain. Extensive simulation study is carried out to evaluate the performance of our approach. Compared with existing ones, our algorithm improves not only bandwidth efficiency but also robustness and fairness. It achieves significant performance improvement for the well-behaving traffic classes in term of bandwidth link utilization, bandwidth blocking,and LSPs preemption.

In MPLS (Multi-Protocol Label Switching) over optical networks, both the optical level and the MPLS level fault recovery can be considered. Generally, a more flexible path arrangement can be realized by the MPLS level recovery, while fast recovery can be achieved by the optical level recovery. When the optical level recovery is adopted, only normal traffic is carried through the working lightpaths and only recovered traffic is carried through the backup lightpaths. In contrast, the working LSPs (Label-Switched Paths) and the backup LSPs corresponding to other working LSPs can be accommodated into an identical lightpath when the MPLS level recovery is adopted. By such sophisticated accommodation of LSPs into the lightpaths, lightpath bandwidth can be utilized efficiently under the condition that the bandwidth utilization is restricted to attain the given objective of transfer quality for the MPLS packets in the normal state and unrestricted in a short time a failure occurs somewhere in the network. This paper proposes a simple mathematical programming model to obtain the optimum arrangement of the working and backup LSPs assuming the MPLS level recovery and a practical LSPs provisioning mode. By comparing the minimized network cost obtained from the optimum arrangement of the working and backup LSPs with the network cost resulting from the optical level recovery, this paper quantitatively evaluates the effectiveness of such bandwidth utilization improvement obtained from the MPLS level recovery and reveals that the MPLS level recovery can actually reduce the network cost due to its flexible arrangement of LSPs on the lightpaths.

We propose a new algorithm for guaranteed bandwidth routing. The problem is motivated by the needs of service providers to set-up bandwidth guaranteed paths quickly in their backbone or transport networks. For that, one way to provide a routing bandwidth is to use MPLS (multiprotocol label switching). An important context in which these problems arise is that of a dynamic label switched path (LSP) set up in MPLS between ingress and egress nodes. The routes of the LSPs can be specified explicitly. In addition, with the establishment of backup LSPs, a network will be able to cope with failure in nodes and links.

Aggregates of real‐time traffic may experience changes in their statistical characteristics often manifesting non stationary behavior. In multi protocol label switching (MPLS) networks this type of the traffic is assigned constant amount of resources. This may result in ineffective usage of resources when the load is below than expected or inappropriate performance when the load is higher. In this paper we propose new algorithm for dynamic resource adaptation to temporarily changing traffic conditions. Assuming that network nodes may reallocate resources on‐demand using automatic bandwidth adjustment capability of MPLS framework, the proposed algorithm, implemented at ingress MPLS nodes, dynamically decides which amount of resources is currently sufficient to handle arriving traffic with given performance metrics. This decision is then communicated to interior MPLS nodes along the label switched path. As a basic tool of the algorithm we use change‐point statistical test that signals time instants at which statistical characteristics of traffic aggregates change. The major advantage of the proposed approach is that it is fully autonomous, that is, network nodes do not need any support from hosts in terms of resource reservation requests. The proposed algorithm is well suited for traffic patterns experiencing high variability, especially, for non stationary type of the traffic.

Fast network re-optimization schemes for MPLS and optical networks

This paper presents a hierarchical approach for modelling an MPLS (Multi-Protocol Label Switching) network using VHDL (Very high-speed integrated circuits Hardware Description Language). The MPLS technology is used because it offers a better performance and flexibility than IP routing. Six MPLS switches are modelled and simulated as follows. A label is assigned to the IP packet header by the first switch, which indicates the route that the frame must follow in the MPLS network. This label is then used by the MPLS middle switches for its management inside the network. Four middle switches change the label depending on the destination of the packet. The final switch removes the label of the IP packet header and the frame continues its path outside the MPLS network. Simulation results show that this approach allows the simulation of large networks consisting of even 256 MPLS switches.

The emerging multi-protocol label switching (MPLS) networks enable network service providers to route bandwidth guaranteed paths between customer sites (see Davie, B. and Rekhter, Y., 2000; Awduche, D. et. al., 1999; Sharma, V. et al., 2002; Jamoussi et al., 2002). This basic label switched path (LSP) routing is often enhanced using restoration routing which sets up alternate LSPs to guarantee uninterrupted connectivity in case network links or nodes along the primary path fail. We address the problem of distributed routing of restoration paths, defined as follows: given a request for a bandwidth guaranteed LSP between two nodes, find a primary LSP and a set of backup LSPs that protect the links along the primary LSP. A routing algorithm that computes these paths must optimize the restoration latency and the amount of bandwidth used. We introduce the concept of to bound the restoration latency. We consider three different cases characterized by a parameter called backtracking distance, D: (1) no backtracking (D=0); (2) limited backtracking (D=k); (3) unlimited backtracking (D=/spl infin/). We use a link cost model that captures bandwidth sharing among links using various types of aggregate link state information. We first show that joint optimization of primary and backup paths is NP-hard in all cases. We then consider algorithms that compute primary and backup paths in two separate steps. Using link cost metrics that capture bandwidth sharing, we devise heuristics for each case. Our simulation study shows that these algorithms offer a way to tradeoff bandwidth to meet a range of restoration latency requirements.