Survivable ATM mesh networks: Techniques and performance evaluation

Due to the explosive growth of real-time and multimedia-oriented applications and services on the Internet, network survivability becomes much more important than before. Future mobile broadband IP networks will be generalized multiprotocol label switching (GMPLS) based. Many protection and restoration (P&R) techniques have been developed to improve survivability in GMPLS-based IP networks. We propose an efficient two-level P&R scheme for GMPLS-based IP networks. In the scheme, LSP (label switched path) P&R is the first level and LSP segment P&R is the second level. An LSP protection path selection (LPPS) algorithm has been designed for the proposed scheme. The protection path establishment acceptance rate can be improved in the scheme. The proposed scheme achieves better quality of service (QoS) and reliability guarantees. In addition, a shorter failure recovery time can be obtained.

The paper proposed the application of the PWR scheme to generalised multiprotocol label switching (GMPLS) networks. Simulation results indicates that the PWR scheme outperforms the AR scheme in terms of expected network blocking probability, while achieving comparably fast restoration completion times. Due to its contained signaling and robustness during traffic changes, the PWR scheme may be a good candidate for GMPLS networks subject to frequent traffic changes. The network utilization factor, /spl eta/, is defined as the ratio between the sum of the number of working wavelengths on all links and the total network capacity.

Elastic Optical Networks (EON), which are able to allocate an appropriate optical spectrum range and modulation format to an optical path according to the client (e.g. IP) traffic demand and path attributes (e.g., physical length or optical impairments), have been proposed to more efficiently utilize network spectrum resources. A control plane is a key enabling technique for dynamic and intelligent end-to-end path provisioning and recovery in such networks. In this paper, we design and deploy two different control planes for EON. One is based on the Generalized Multi-Protocol Label Switching (GMPLS) / Path Computation Element (PCE) architecture and protocols, and the other one is based on a centralized model extending OpenFlow. We detail the protocol extensions involved in the main functional aspects, and we experimentally validate both control plane approaches in a control plane testbed and compare them in terms of path provisioning latency.

Hierarchical approach for survivable network design

This paper presents an application of Artificial Bee Colony (ABC) algorithm for survivable optical network design. The dedicated path protection (DPP) survivability scheme is modelled by ABC algorithm for establishing two link-disjoint paths between each node pair in demand matrix considering single link failure scenarios. In the proposed algorithm every food source represents a lightpath between each node pair in optical network and the position of food sources are modified by artificial bees to minimize the total number of utilized wavelengths by working and spare lightpaths. Simulation results demonstrate that the proposed ABC based survivability scheme is able and efficient to design fault-tolerant optical transport networks.

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.

Ultra-high capacity transmission systems utilizing dynamic photonic switches enable transparent networking with reduced optoelectronic conversions and simplified and automated operations and maintenance. Due to recent advances in control functions for wavelength switching in optical networks, network service providers envision the same level of automated connection provisioning and restoration capabilities at the wavelength layer as offered by time division multiplexing (TDM) or packet switched networks. Implementing Generalized Multiprotocol Label Switching (GMPLS), transparent networks can offer a high level of reliability with automatic restoration as well as reduced resources compared to legacy 1 + 1 protection mechanisms. Based on preplanned path computation, selection, signaling, and allocation of optical resources, three recovery schemes are described in the context of the wavelength connections: protection, dynamic restoration, and a combination of protection and restoration. Through the use of network simulations, we analyze the impact of transparency constraints such as optical switch activation delay and sequential light path establishment on the recovery time. This analysis includes the trade-off between different recovery strategies and transmission system reach. é 2010 Alcatel-Lucent.

This paper describes multilayer traffic engineering and signaling technologies in a photonic-GMPLS-router network. Multilayer traffic engineering, which yields the dynamic cooperation of IP and photonic layers, is described to provide IP services cost-effectively. To realize multilayer traffic engineering, we propose the OSPF extension, which advertises both the number of total wavelengths and the number of unreserved wavelengths, and the RSVP-TE extension, which realizes the least number of wavelength conversions. In addition, this paper presents a heuristic-based multilayer topology design scheme that uses IP traffic measurements in a generalized multiprotocol label switch (GMPLS). Our design scheme yields the optical label switch path (OLSP) network topology, i.e. OLSP placement, that minimizes network cost, in response to fluctuations in IP traffic demand. In other words, the OLSP network topology is dynamically reconfigured to match IP traffic demand. Networks are reconfigured by the proposed scheme so as to utilize the network resources cost-effectively.

Next generation backbone networks will likely consist of IP routers as well as optical cross connects and will deploy Generalized Multiprotocol Label Switching (GMPLS) as the control plane protocol. The fiber carries large volume of traffic and therefore one must ensure that adequate mechanisms are in place that facilitate automatically recovery from failures. In mission critical networks survivability becomes critical. We investigate the problem of autonomous recovery in such networks. The literature contains work in this area that investigates the problem of multilayer recovery. Such recovery had only been sequential in the sense the published work recovers first in the optical domain and then proceeds to recover in the IP plane. We report for the first time a recovery procedure that recovers concurrently in both the optical and IP planes. The work on concurrent recovery investigates a single link failure scenario. While formulating the concurrent recovery protocol, we realized that modifications or extensions were needed to OSPF-TE protocol employed with GMPLS-based WDM networks. The OSPF-TE extension requires that the link state information propagated by the protocol must also carry available unused lambda label switched paths (λLSPs). After a link failure, the ingress node upstream from failed link will first determine the availability of free light paths and existing unreserved bandwidth in used light paths from the link state information provided by OSPF extension. The concurrent multilayer recovery scheme proposed here uses this information to switch traffic in both optical and IP layer concurrently. An OPNET-based simulation study shows that the concurrent two-layer recovery scheme performs as much as forty-four percent faster than the sequential two-layer recovery scheme.

QoS routing in GMPLS-capable integrated IP/WDM networks with router cost constraints

Routing and planning of working capacity and spare capacity in WDM networks were investigated. Joint optimization technique has been used and the problem has been formulated to restore the general failure scenarios. The difference between the cost for the restoration of one node failure and the cost for the restoration of one link failure is decreased as more wavelengths per fiber are used. The difference between the cost of virtual wavelength path (VWP) network and the cost of wavelength path (WP) network is increased as more wavelengths per fiber are used.

Proliferation of nodes has been suggested as a means to achieve reliable communications even when a significant fraction of a network is destroyed. The authors examine issues associated with the design of proliferated, survivable networks based on a layered architecture. A concept for proliferated network operation is outlined, and measures of network performance are described. Threats to each network layer are examined, and survivable network design issues are discussed. It is concluded that proliferating network nodes, using multimedia and interconnecting networks, can enhance communication network survivability. >

Given a placement of wireless nodes in space and a traffic demand between pairs of nodes, can these traffic demands be supported by the resulting network? A key issue for answering this question is wireless interference between neighbouring nodes including self interference along multi-hop paths. This paper presents a generic model for sustainable network load in a multi-hop wireless network under interference constraints, and recasts this model into a multicommodity flow problem with interference constraints. Using Farkas' Lemma, we obtain a necessary and sufficient condition for feasibility of this multicommodity flow problem, leading to a tight upper bound on network throughput. Our results are illustrated by examples.

Given a placement of wireless multi-radio nodes in space and a traffic demand between pairs of nodes, can these traffic demands be supported by the resulting network? The key issue in this setting is the wireless interference between neighbouring nodes using the same channel, including self-interference along multi-hop paths. We extend previous work addressing this problem taking into consideration the availability of multiple channels. As such, this paper presents a generic model for sustainable network load in a multi-hop multichannel setting and recasts this model in a multicommodity flow problem with interference constraints. A theorem is stated which gives a necessary and sufficient condition for the feasibility of this multicommodity flow problem. From this theorem an upper bound is derived for the throughput that can be achieved by the network, which is illustrated by examples. We indicate how the results can be used as a basis for a channel allocating algorithm.

Passive Optical Network (PON) deployments have recently been aiming to combine the capacity of metro and access networks in the last mile of the Internet service provisioning. Deployment of PONs by running fiber to the premises introduces the advantage of huge capacity but at the same time, it calls for a robust design in order to avoid long service outage durations in case of network failures where survivable network design is mostly limited to the deployment budget. In this paper, we propose three mixed integer linear programming (MILP) models for various survivability policies to deploy reliable long-reach PONs under the budget limitations. Each MILP model aims to place the ONUs in optimal locations so that the covered area is maximized while availability requirements of the users are satisfied within the deployment budget. We solve the MILP models under the uniform and heterogeneous availability requirement scenarios and show that service availability and coverage introduce a trade-off so as the coverage and deployment cost do. Two out of the three survivability policies can guarantee 99.99% service availability while the third one is able to guarantee 99.999% by running the proposed MILP models. However, the first two schemes are able to cover larger area when compared to the third scheme which is the most reliable protection policy.