We make an extension to the label distribute protocol in order to realize optical connection management in automatically switched optical network. Its characteristics, such as the dynamic lightpath creation and deletion, and fast restoration are investigated and tested experimentally. How to handle failures occur during these two processes is also explained in detail. The experiment results are discussed and compared with others¡¯ previous work. The experiment setup which is made of four optical nodes and of mesh type network is also described in details in the paper.

Reconfigurable optical network, the way of the future, can encounter serious packet loss problem during optical level reconfiguration. This paper presents a novel buffering scheme for GMPLS optical networks that minimizes packet loss during reconfiguration of optical nodes, consisting of both a reconfigurable optical cross-connects (OXCs), or an optical add-drop multiplexers (OADMs), and a packet-capable layer-two switch [1]. In this scheme, buffering takes place whenever an optical path is altered due to either a node reconfiguration or protection/restoration. Packets are buffered in a distributed manner starting from the first O/E/O-capable node before the reconfigured optical node all the way to the ingress node, if needed. In the worst-case scenario, where the path is all-optical or buffers are full along the path, all incoming packets are buffered at the ingress node, or the edge router. Buffering is carried out at layer two so that the interruption of service is kept at a minimum (less than 50ms, if possible). Furthermore, if buffers are overflowed, packets dropping will be carried out in accordance with the QoS levels, which further ensure that QoS of the network is maintained. It is shown by both analysis and simulation methods that this scheme performs quite well on either a general local area network, such as the UMBC WDM optical testbed, or the MCI backbone network. It is also cost-effective in that, even at the worst-case scenario, the required buffer is quite small.

Although All-Optical Network (AON) are a viable technology for future telecommunication and data networks, it creates many security vulnerabilities that do not exist in traditional networks. Transparency and non regeneration features make attack detection and localization difficult, because the effects of an attack connection can propagate quickly to different parts of a transparent All-Optical Network. Among all attack types in AON, crosstalk attack's propagation capability is second to none. Quick detection and localization of such attack source can avoid losing large amounts of data in an All-Optical Network. However, to detect attack sources, it is not necessary to put monitors on all nodes. Since those connections affected by the attack connection would provide valuable information for diagnosis, we show that placing a relatively small number of monitors on a selected set of nodes in a network is sufficient to achieve the required level of performance. This paper introduces crosstalk attack model and monitor-segment concept. After showing a necessary and sufficient condition for one-OAF diagnosable AON, a new sparse monitor placement method is proposed.

Management network plays an important role in the SDH transport system. Adopting the management architecture of CMIP, traditional SDH management network is chiefly a subset of TMN. Although its management ability is powerful, it is complex to implement. Considering not only the SNMP's simplicity and low resource consumption but also the flexible extensibility brought by the application of the extensible agent (AgentX) architecture, a different strategy of the SDH management network based on the SNMP management structure with AgentX is proposed in this paper. The design scheme of AgentX in the system is discussed further.

This paper presents an architecture that provides a unified web interface to managed network devices that support CORBA, OSI or Internet-based network management protocols. A client gains access to managed devices through a web browser, which is used to issue management operations and receive event notifications. The proposed architecture is compatible with both the OSI Management reference Model and CORBA. The steps required for designing the building blocks of such architecture are identified.

With evolution of Internet, next generation Internet primarily is a network-service-driven. In the future, Especially, Telecommunication network, computer network and wireless mobile network will be merged into an all-IP network, services provided by this large scale network will increase by exponent. This will result in some critical problems--how to effectively manage these services provided by such network to make service users obtain their QoSguaranteed-service at anytime and anywhere. Study shows that the interaction between service providers and service users, in practice, is a service level agreement (SLA) process. Therefore, SLA acts as quite importance, In this paper, a kind of perspective of using service location protocol (SLP) to implement SLA is proposed based on fully researching of SLP. The main idea is as follow: information of SLA object can be bound to user agents' (UA) request messages. Comparison with conventional method, it not only cuts down the agreement numbers between service providers and service users, but also saves network bandwidth and guarantees QoS.

Intrusion detection systems have usually been developed using large host-based components. These components impose an extra load on the system where they run (sometimes even requiring a dedicated system) and are subject to tampering or disabling by an intruder. Additionally, intrusion detection systems have usually obtained information about host behavior through indirect means, such as audit trails or network packet traces. This potentially allows intruders to modify the information before the intrusion detection system obtains it and slows down the detection and prevention of DoS attacks, making it possible for an intruder to hide his activities. In this paper we propose work that will attempt to show that it is possible to perform intrusion detection mechanism of DoS attacks using small sensors embedded in a computer system. These sensors will look for signs of specific intrusions. They will perform target monitoring by observing the behavior of the through an audit trail or other indirect means in real time while the Snort IDS running. Furthermore, by being built into the computer system it could provide a flexible alert sensor which may not impose a considerable extra load on the host they monitor.

Computer Network Management is the most important work of the computer network. Two problems in managing of a professional network must be solved, one is to standardize the relationship between the professional network and the management network, and the other is to ensure the security of the network. The first problem will be discussed here. We put forward a new idea here, that is, to build standard computer management network and standard professional network. First, we give a standard model of the relationship between the management network and its subordinate professional network. This model is different with the TMN. It distinguishes the management network and the subordinate professional network clearly in the notion, the place and the property of all the sockets is determined. Subsequently, the corresponding function structure and physical architecture are given together. For each kind of architecture, we define the related rules respectively. These rules are: the relationship between the function module, the standard of the interface, protocol architecture. Then, the procedure of communication signal processing is analyzed. The requirements of all the programming sockets are explained. Finally, we explain some related topics briefly.

In this paper, two new broadcasting protocols are proposed for providing video-on-demand (VoD) services in multicast environment. The two protocols are developed by introducing a new first-segment delivery scheme for the skycraper and staggered protocols. With our approach, the first segment of a video is further divided into a number of small pieces so that customers can download the request data and start watching the video in a shorter time. The results show that the start-up latency for users is greatly reduced when using our new protocols.

A concept to design robust and flexible, fully transparent, optical long-haul networks without additional Raman-Amplification is demonstrated theoretically and experimentally. Excellent performance and flexibility at data rates up to 10 Gbit/s and transparency lengths of more than 1700 km are predicted by computer-simulations and successfully demonstrated in a field-test. Error-free transmission of arbitrary data-rates up to 10 Gbit/s over variable link distances up to 1720 km could be demonstrated without intermediate 3R-regeneration and without additional Raman-Amplification and Forward Error Correction. This field-experiment demonstrates the technical feasibility of extensive and flexible, fully transparent optical WDM-Networks.

A new implementation of the modulation phase-shift technique is presented that is well adapted for field use. The method uses measurements of modulation amplitudes to compute relative group delays (RGD). Unlike existing phase-shaft-method implementations, this technique requires no control or calibration of relative phases in the electrical domain. For RGD measurements, a broadband LED emitter - tunable filter receiver combination is used. With this simple set-up, ten RGD measurements taken at 16 different wavelength points (i.e. over 160 measurements) gave standard deviations of 2 to 6 ps. Standard fiber (non-zero dispersion shifted) lengths of over 160 km are accurately measured.

The paper presents several tunable devices used for optical spectral performance monitoring. The first type of devices is constructed out of a Fabry-Perot resonator filled with liquid crystal that is to be used for performing the spectral scanning. Another type of filters is based on birefringent filters to be applied for spatial imaging systems. The paper presents the design of the devices as well as its anticipated performances.

This paper examines the integration of optical multicast and VOA functionalities into an optical switch. The paper contains an analysis of the different methods available today to perform such integration, as well as a detailed investigation of some of the applications that stand to benefit from such integration. Integrated switching, multicast and VOA functionalities are offered using several different technologies. The leading technologies are integrated optics, polarization based devices. Some applications that stand to benefit from such devices include: Next generation optical protection schemes - realizing dynamic optical protection schemes in both ring and mesh networks requires both switching and VOA functionalities. Cost effective 1+1 schemes in mesh networks may benefit from multicast functionality as well, Reconfigurable optical networks - Dynamic provisioning in optical networks mean that the wavelength path in the network is not fixed. This requires both VOA and switching functionality to execute the dynamic reconfiguration, Next generation optical amplifiers, Optical multicast networks.

Recently, researchers have investigated the use of photonic circuit switching, or optical time division multiplexing, as a mean to sub-divide the bandwidth of wavelength channels in Dense Wavelength Division Multiplexing networks. In this paper, we present our study on the use of optical buffer in a photonic circuit switching network and how routing and time-slot assignment can be used to optimize the effectiveness of optical buffer. We will also discuss how photonic circuit switching may be integrated into the emerging IP-centric control and management scheme of GMPLS.

This paper studies the virtual topology design of wavelength-routed WDM networks. The focus is on the virtual topology design problem taking into account the quality of service (QoS) requirements of different user applications. To provide diverse QoS levels to meet different QoS requirements, we first propose a QoS model for WDM networks, in which we define four types of optical connections, each providing a diverse QoS level in terms of the transmission bandwidth and end-to-end delay. Correspondingly, we classify the network traffic into four categories with different QoS requirements for using the four types of connections. Based on this QoS model, we then formulate the virtual topology design problem as a linear programming problem with an objective to maximize the network throughput, and give an exact formulation of the problem.

Wavelength reservation protocols can be employed to dynamically set up and tear down lightpaths in WDM networks. The performance of these protocols in single-fiber WDM networks has been extensively studied. In this paper, the signaling protocols are extended for multi-fiber networks and novel wavelength selection policies are proposed. We compare the performance of different protocols in both single-fiber and multi-fiber WDM networks. The simulation results show our novel wavelength selection policies excel the other schemes. Related discussions on these results are included.

Passive optical networks (PONs) have recently emerged to be a promising approach to enhance the penetration of fiber towards the subscriber side, thus further enables delivery of higher data-rate services to the subscribers. They feature easy network maintenance as there is no active component at the remote node (RN). However, in conventional PONs, both upstream and downstream bandwidths have to be time-shared among all optical network units (ONUs). By applying WDM technique to PONs, the total system capacity can be further enhanced. Each ONU enjoys a dedicated bandwidth and resolves the ranging problem as in PONs. In both conventional PON and WDM-PON, little work has been done to offer protection capability though fiber fault detection methods have been extensively studied. We propose a novel network architecture for WDM-PON which offers 1:1 protection capability. In case of any fiber cut between remote node and ONUs, the affected ONU can re-route the wavelength channels via the adjacent ONU and can still maintain normal bidirectional traffic.

We propose a Tabu Search (TS) algorithm to solve the problem of designing a logical topology for packet-switched traffic over a WDM mesh network. The cost of mapping such a logical topology over a physical network is taken into account. The algorithm provides approximate solutions of good quality (i.e., close to the optimal ones) to the corresponding optimization problem and allows us to solve problem instances of large size, which is usually impossible with algorithms solving exactly the Integer Linear Programming (ILP) formulations of the problem. The algorithm makes it possible to evaluate the cost-performance tradeoff between designing a logical topology with small congestion and a large number of (possibly expensive) lightpaths and designing a less expensive topology with higher congestion.

Future communication networks will carry many WDM channels at very high bit rate. Thus, it is desirable to avoid electronic switching at the core. The all-optical backbone network can be interconnected by optical cross-connects at strategic locations to allow for flexible capacity provisioning and fault-tolerant rerouting. Such an all-optical core layer nicely decouples the long-term capacity planning problem from the short-term dynamic bandwidth allocation problem which can be better tackled in the electronic domain. An essential requirement for the all-optical core layer is that it must be fully fault-tolerant, otherwise, a single failed link can cause a disaster for the entire network. We consider the problem of how to allocate the required capacities and spare capacities on a given all-optical core network so as to make the network fully single-fault (or multi-faults) tolerant. The objective function is the total cost of the spare fibers. Based on a given traffic requirement on all source-destination pairs, the optimal bandwidth requirement for each link in the given topology is first computed. We then consider link failures one-by-one for the entire network. For each link failure, we show how spare capacity can be added in other links so as to take advantage of existing spare capacities that have already been added. The algorithm is based on the shortest path routing algorithm and has a polynomial time complexity. Preliminary investigations suggest that the algorithm can give results comparable to those obtained by integer programming.

In our paper, we present a heuristic method for maximizing the utilization of a survivable multi-ring DWDM network without wavelength conversion. We assume that the network is supporting packet and circuit based services simultaneously. The idea is that we can provide ample bandwidth or even dedicated channels to packet based services by sharing the resources in the protection ring under normal conditions. In case of a ring failure, the packet based channels can be compressed into fewer channels to yield protection bandwidth to circuit based services. Packet ring technologies such as Resilient Packet Ring (RPR) or IEEE 802.17 will ensure that all packet connections are still maintained in a fair manner under such condition. The main contribution in this work is to jointly consider the effect of packet and optical connection services on DWDM rings to enhance wavelength utilization.

In this paper, we discuss the load balancing issues for wavelength-routed optical networks. After a definition of load balancing factor, which evaluates the fairness of the wavelength usage on each link, a new Integer Linear Program (ILP) formulation is proposed for routing and wavelength assignment for WP and VWP-RWA scheme. As the ILP is time-consuming for large-scale networks, an effective heuristic algorithm is given. In this paper, we use three metrics to quantify the performance improvement by our method: Load balancing factor FF, wavelength requirement N_λ and wavelength reusability ρ. In both WP and VWP schemes, our load balancing algorithm achieves much better performance than Fixed-shortest-path and alternate-shortest-paths routing algorithms.

The growth of the Internet and the World Wide Web has created an enormous demand for wideband data distribution around the globe. Satellite networks provide global reach and wide area coverage, especially to remote, rural and inaccessible regions. With a limited bandwidth, congestion is likely to occur when the demand for the bandwidth is high. In this paper, we present a capacity and flow assignment (CFA) model for the satellite ATM networks. We then present a stochastic programming approach to optimize the CFA in the satellite networks. The proposed model has been evaluated with a prototype network with 4 nodes, and the simulation results are promising.

The latest evolution of packet switching networks is represented by the DiffServ and MPLS architectures, where much attention has been paid to the issue on traffic stream priorities. This article addresses some subsequent issues. First, it seems reasonable for routers to include the preemption policy into packet scheduling. Secondly, the parallel forwarding may find its indispensable place. Thirdly, the path-node incidence is perhaps more appropriate for network modeling than the link-node incidence. Finally, it appears that nonlinear models incorporating load-dependent parameters would play a role in future IP networks. In summary, the 3P or 4P features -- Priority, Preemption, and Parallelism plus Path-node incidence may bring significant changes into the nowadays packet switching networks.

This paper introduces a model that can be used to share link capacity among customers under different kind of traffic conditions. This model is suitable for different kind of networks like the 4G networks (fast wireless access to wired network) to support connections of given duration that requires a certain quality of service. We study different types of network traffic mixed in a same communication link. A single link is considered as a bottleneck and the goal is to find customer traffic profiles that maximizes the revenue of the link. Presented allocation system accepts every calls and there is not absolute blocking, but the offered data rate/user depends on the network load. Data arrival rate depends on the current link utilization, user's payment (selected CoS class) and delay. The arrival rate is (i) increasing with respect to the offered data rate, (ii) decreasing with respect to the price, (iii) decreasing with respect to the network load, and (iv) decreasing with respect to the delay. As an example, explicit formula obeying these conditions is given and analyzed.

In the construction of a communication network, the length of the network is an important but not unique factor determining the cost of the network. Among many possible network models, Gilbert proposed a flow-dependent model in which flow demands are assigned between each pair of points in a given point set A, and the cost per unit length of a link in the network is a function of the flow through the link. In this paper we first investigate the properties of this Gilbert model: the concavity of the cost function, decomposition, local minimality, the number of Steiner points and the maximum degree of Steiner points. Then we propose three heuristics for constructing minimum cost Gilbert networks. Two of them come from the fact that generally a minimum cost Gilbert network stands between two extremes: the complete network G(A) on A and the edge-weighted Steiner minimal tree W(A) on A. The first heuristic starts with $G(A)$ and reduces the cost by splitting angles; the second one starts with both G(A) and W(A), and reduces the cost by selecting low cost paths. As a generalisation of the second heuristic, the third heuristic constructs a new Gilbert network of less cost by hybridising known Gilbert networks. Finally we discuss some considerations in practical applications.

The traffic control is a critical issue in ATM networks. In ATM, the traffic control is implemented at different levels: cell level, call level and network flow level. The virtual path (VP) distribution involves both call level and flow level controls. The VP distribution is a logic network design problem based on the physical network. Several VP optimization schemes have been proposed, and a large number of these schemes are based on the flow assignment (FA) model. In this paper, an improved flow model is proposed with a non-linear objective function. The proposed model incorporates two concepts: VP capacity and VP flow, to perform the optimization. The proposed model distributes traffic on all available VPs evenly, and has redundant capacities. Hence, the resulting VP system is resilient to input traffic changes and physical link failures. In addition to the proposed FA model, we introduce a stochastic programming (SP) methodology to allocate virtual paths when the incoming traffic changes stochastically. Experimental results show that the proposed flow model and the stochastic methodology improve the performance of ATM networks.

This paper considers a business model that involves two layers in the telecommunications capacity market: wholesaler and retailer. It introduces a new reliability measure to benefit network retailers. Unlike previously proposed measures, the measure considers further service degradations once the network is disconnected. This measure can be used, in principle, by the network retailer to select an optimal set of paths in order to achieve a desired compromise between cost and reliability.

Pre-configuration of spare capacity in cycle, for the design and operation of survivable mesh-restorable networks, is virtually as efficient in capacity as a conventional mesh restorable network, but it offers the potential for restoration speed approaching that of a line-switched ring. But the algorithm [1] bought forward has a slower convergence speed and a based-improved-ring score centralized algorithm [2] made the restoration process more complex .We proposed a new method that can speed the convergence as well as keep the restoration control process simple.

A key management approach of multicast is provided in this paper. It is based on the approach of assignment key to every group member through key center. In view of some management schemes where members join, leave or are deleted, key service center must distribute new key through unicast another time. The bigger amount of members the greater expenses will be spent. In this paper with member varying their upper key service center still distribute the new keythrough multicast and an ID is assigned to every member to identify their transmission message so as to implement data origin authentication. The essential principle of this approach is distributing a key generator for each member. For example a random number generator depending on certain algorithm can be distributed. And every member needs store a seed table. In this project key can automatically be renewed as time goes by or immediately renewed. Replace unicast by multicast to renew key decrease the spending. It is not only suitable for the key centralized management scheme with fewer members but also for the key separated management scheme with large group members and member frequently changed.

The blocking performance of two types of all-optical networks: wavelength-selective (WS) and wavelength-interchangeable (WI) networks, is studied. Efficiency of different dynamic routing and wavelength assignment (RWA) algorithms, including adaptive routing algorithms and dynamic alternate routing algorithms, is investigated. Dynamic wavelength assignment combined with adaptive route selection algorithm is also presented and investigated. Numerical results show that multifiber WS networks may provide a viable and economical alternative to WI networks, and dynamic alternate routing algorithms is also a good substitute to adaptive routing algorithms. The presented dynamic wavelength assignment combined with adaptive route selection algorithms exhibit better efficiency than other ones. The study also shows that the efficiency of different dynamic RWA algorithms is dependent with different topologies, and the performance gain of wavelength conversion in regular topology is not as significant as in irregular topology networks, meanwhile, the efficiency of different dynamic RWA algorithms is closely related with the number of alternate routes.

In this paper an implementation approach of IPSec inside host operating system is given, which is composed of three main modules: Kernel IPSec module, where AFT, ESP and theirs encapsulation in kernel are implemented, Key Management Process module, where IKE consultation and its connection with other parts are implemented, and Interface module. The whole implementation approach is introduced and each component part is detailed. The implementation diagram is shown. Several key points such as policy management and so on which should be considered in implementation are provided. Main software flow diagrams are illustrated. Some functions are mentioned. The integrated approach inside operation system presented in this paper is modularized to three parts, and every part is supported by its backstage procedure. So this approach is characterized by easily disposal and transplant. For example it also can be conveniently applied to router software to implement integration inside router.

With the emergence of optical cross-connects (OXCs) and optical add/drop multiplexers (OADMs), all-optical networks and a new layer named as optical layer are emerging. Although the number of available wavelength per fiber and the bandwidth per wavelength are all becoming larger, the total bandwidth per fiber is limited. So for a network operator, pre-allocating minimum spare capacity in an optical network under the advanced connection demands to meet to survivability requirements is needed. In this paper, the above problem can be formulized as an ILP model, in which different survivability requirements of connections are considered jointly. The solution to this problem has an advantage over the result of the separate allocation problem, i.e., allocating resources for service connections and protection! restoration connections are performed separately.

WDM ring network is gaining acceptance as its flexibility, simple management and well survivability. This paper looks at several kinds of WDM ring protection networks and some problems, which we must pay attention to, and then analysis and compares their performance. Finally, we give some principles of design the WDM ring protection networks.

With the development of transport networks, it must face many new challenges for the increased network survivability. In this paper, we analyses the problems of coordination between the individual layers recovery mechanisms. Based on the comparing of present three coordination methods, we propose a new coordination method, that is ¡° recovery ratio platform¡± method. This method can efficiently increase the restoration ratio and decrease the restoration time.

The benefits of restoration in meshed compared to ring based transmission networks are widely accepted and recognized. This article goes a step further and analyzes the benefits of a collaboration between an IP/MPLS and optical restoration. The underlying principle is based on managed control planes and provides substantial cost savings compared to unrelated restoration mechanisms.

With its low cost, ubiquity, and scale, Ethernet is the technology most widely envisioned to change the economics of packet service delivery for both carriers and their customers. This paper discusses a new architecture that simplifies and lowers the cost to deliver data services. By fully integrating Ethernet with existing SONET/SDH networks in a "Virtual Ethernet Ring," carriers can now provide a multipoint Ethernet service that can span long distances across multiple metro areas. This architecture leverages the plug-and-play advantages of Ethernet - auto-provisioning, broadcast and discovery, etc. - across a distributed wide area network. It provides the advantage of granular, software-provisioned bandwidth to the customer. It also provides SONET/SDH quality resilience with security and bandwidth guarantee. By incorporating protocol mediation technology, this architecture enables the migration from today's frame relay, ATM and IP services to a new generation of granular, readily scalable Ethernet services such as Ethernet Private Line, Ethernet Virtual Private Lines and Internet/Frame Relay/ATM/Access Services.

DWDM transmission is the enabling technology currently pushing the transmission bandwidths in core networks towards the multi-Tb/s regime with unregenerated transmission distances of several thousand km. Such systems represent the basic platform for transparent DWDM networks enabling both the transport of client signals with different data formats and bit rates (e.g. SDH/SONET, IP over WDM, Gigabit Ethernet, etc.) and dynamic provisioning of optical wavelength channels. Optical Performance Monitoring (OPM) will be one of the key elements for providing the capabilities of link set-up/control, fault localization, protection/restoration and path supervisioning for stable network operation becoming the major differentiator in next-generation networks. Currently, signal quality is usually characterized by DWDM power levels, spectrum-interpolated Optical Signal-to-Noise-Ratio (OSNR), and channel wavelengths. On the other hand there is urgent need for new OPM technologies and strategies providing solutions for in-channel OSNR, signal quality measurement, fault localization and fault identification. Innovative research and product activities include polarization nulling, electrical and optical amplitude sampling, BER estimation, electrical spectrum analysis, and pilot tone technologies. This presentation focuses on reviewing the requirements and solution concepts in current and next-generation networks with respect to Optical Performance Monitoring.