Leased Line Services Research Articles

Innovation and demonstration of optical service unit-based metro-optimized OTN technologies

To efficiently support the transport of sub-1-Gbps services, an optical service unit (OSU)-based metro-optimized optical transport network (M-OTN) technology framework is proposed and described. The proposed M-OTN/OSU technologies have been implemented by major OTN equipment vendors and verified in a network operator’s lab for the first time to our knowledge. Moreover, a multivendor interoperability test has been conducted in a real-time field trial. The experimental results show that M-OTN/OSU has clear advantages over existing SDH VC/packet-enhanced OTN technologies in several key aspects, e.g., low latency, massive connections, and agile hitless bandwidth adjustment. M-OTN/OSU will be valuable for network operators providing high-quality leased line services and video/VR services in modern OTNs with unprecedented scalability and performance.

IP/MPLS networks with hardened pipes: service concepts, traffic engineering and design considerations

The concept of embedding a hard pipe within IP/MPLS network architecture has recently been proposed in IETF RFC 7625 contribution as an advanced networking architecture to address the need of many large organizations and utility companies for TDM-like leased line services with end-to-end guaranteed bandwidth, low delay and high reliability in order to support pervasive mission-critical applications. In this paper, we carry an in-depth investigation of the traffic engineering and design considerations that need to be taken into account when deploying hard pipe strata in IP/MPLS networks. In particular, we focus on LSP provisioning, QoS management, time synchronization, availability, delay/jitter requirements and interoperability considerations. We discuss some of the design and traffic engineering alternatives, critique their relative merits and propose some recommendations to enhance bandwidth usage, provide support for delivering end-to-end QoS and maximize revenues. Finally we propose future research prospects in the search of additional traffic engineering mechanisms to further optimize resource allocations, bandwidth usage and SLA compliance.

Optical dynamic circuit services

IP service, leased-line service and POTS service have been the three long-standing communication service offerings of providers. Recently, both commercial and research-and-education network providers have started offering optical dynamic circuit services. This article reviews these services, differentiates DCS from leased-line services, offers a classification of DCS, and proposes two new types of DCS. DCS are classified into two types: Specified-Duration Scheduled and Unspecified-Duration Unscheduled. SDS service is less flexible than UDU service in that it requires users to specify call durations, and is more complex (needs reservation schedulers), but it is the only efficient option if link bandwidth is divided into a small number of channels (e.g., 1 Gb/s circuits on a 10 Gb/s link for fast transfers of large files). For SDS offerings, if the mean call duration is small, then a distributed scheduler implementation may be required to handle the high call arrival load required to maintain high utilization levels. Finally, SDS is classified into two sub-types: Specified Start Time and Earliest Start Time, based on whether the user can only accept a start time from within its own specified set of start times, or whether it can accept any, preferably earliest, start time. The SST sub-type is useful for applications requiring the co-scheduling of network bandwidth with other resources, while the EST sub-type is ideal for file transfers.

Modeling of Workflow-Engaged Networks on Radiology Transfers Across a Metro Network

Radiology metro networks bear the challenging proposition of interconnecting several hospitals in a region to provide a comprehensive diagnostic imaging service. Consequences of a poorly designed and implemented metro network could cause delays or no access at all when health care providers try to retrieve medical cases across the network. This could translate into limited diagnostic services to patients, resulting in negative impacts to the patients' medical treatment. A workflow-engaged network (WEN) is a new network paradigm. A WEN appreciates radiology workflows and priorities in using the network. A WEN greatly improves the network performance by guaranteeing that critical image transfers experience minimal delay. It adjusts network settings to ensure the application's requirements are met. This means that high-priority image transfers will have guaranteed and known delay times, whereas lower-priority traffic will have increased delays. This paper introduces a modeling to understand the benefits that WEN brings to a radiology metro network. The modeling uses actual data patterns and flows found in a hospital metro region. The workflows considered are based on the Integrating the Healthcare Enterprise profiles. This modeling has been applied to metropolitan workflows of a health region. The modeling helps identify the kind of metro network that supports data patterns and flows in a metro area. The results of the modeling show that a 155-Mb/s metropolitan area network (MAN) with WEN operates virtually equal to a normal 622-Mb/s MAN without WEN, with potential cost savings for leased line services measured in the millions of dollars per year.

QoS and SLA aspects across multiple management domains: the SEQUIN approach

The aim of this work is to define and implement an end-to-end approach to quality of service (QoS), operating across multiple management domains and exploiting a combination of link layer technologies. The architecture for the Premium IP service is presented, which aims at offering the equivalent of an end-to-end virtual leased line service at the IP layer across multiple domains. Also, the results of the initial testing performed for the validation of the service and the provisioning model for Premium IP are described. The work presented has been carried out in the framework of SEQUIN, a European Commission-funded research project.

Application of control plane technology to dynamic configuration management

The distinction between switched and leased line services is beginning to disappear. Many network operators and suppliers are developing control plane technology for application in transport networks. This will allow faster service provisioning, particularly between network operators, and the creation of new network services. However, such systems will still require comprehensive management systems, and successful operators and vendors of the future will be those that are capable of developing operational support systems that complement the control plane with service management capabilities, automated plan and build processes, inventory management, and capacity planning. This article examines the distribution of functionality between the management and central planes for support of soft permanent and switched connections.

Customer premises networks of the future

B-ISDN based on ATM technologies is expected to offer enhanced and sophisticated services to users, but selecting a graceful migration path is critical. During the introductory stage of the ATM-customer premises network (CPN)/spl minus/as an initial broadband public network service/spl minus/ATM leased-line service will use VP crossconnect network. An efficient CPN interconnection via end-to-end VP pipe therefore would be an attractive application. The possible migration scenario of ATM-CPN is presented, the required functions and services in future CPN are clarified for each evolutional stage, i.e., the introductory, expansion and diffusion stages, and the importance of medium-bit-rate SB interfaces is described. It is also shown that a 10 to 20 Mb/s metallic interface should be introduced as a cost-effective SB interface.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Management of virtual private networks for integrated broadband communication

Management of Virtual Private Networks (VPNs) is becoming an increasingly important issue in the context of integrated broadband communication (IBC). In the near future corporate customers may want to subscribe to broadband VPN services offered by globally operating service providers to replace most of their leased line services that are used today to build their corporate networks. The concepts historically known as characterizing VPNs, such as the concept of closed user groups, will still be valid, but the importance of VPN service features and, in particular, the set of VPN management services offered to VPN customers will become dominant. In this paper we present a detailed technical approach to the management of broadband VPNs based on current technology and common standards. In particular, we discuss architectural solutions, management interfaces and management services provided at these interfaces, as well as managed objects.

ATM VP-based broadband networks for multimedia services

A virtual path (VP) based asynchronous transfer mode (ATM) network architecture that supports leased-line services is described. ATM multimedia leased-line services, including user access to VPs, tailored VP capacity, guaranteed quality of service, and reduced transmission cost, are discussed. It is argued that some issues remain to be resolved before fully realizing the services. The issues include the definition of source traffic descriptors, protocols for VP bandwidth alteration, end-customer control mechanisms, and VP restoration techniques. >

Introduction strategy and technologies for ATM VP-based broadband networks

A credible introduction strategy for B-ISDN is described. The first step is the introduction of asynchronous transfer mode (ATM) techniques into the path layer. The strategy is shown to be effective, since it enables not only the realization of a cost-effective and flexible network infrastructure, but also the provision of high-speed multimedia leased line services. The service advantages possible with virtual paths are also demonstrated. The authors' technical advances, including ATM network resource management techniques and network utilization enhancement techniques, are highlighted. >

Value‐added services

Value‐added is an economist's term meaning that the service offered will have additional value to the user compared with more basic telecommunications (or other) services. Within the telecommunications sector, there has been considerable discussion in recent years as to what constitutes a value‐added service. This argument has now been initially resolved with the publication of a discussion document by the DTI, Value‐added and data services, which defines anything beyond the basic telephone, telex and leased line services as being of a value‐added nature. Thus a telephone answering service adds value, as does an ‘electronic mail’ service linking dissimilar data terminals, perhaps on different continents. The range of service possibilities is very wide and currently seems to be limited only by entrepreneurs' abilities to define commercially attractive presentations of telecommunications services, computers and operators.

The mercury network

Mercury, the licensed competitor to British Telecom is creating a digital telecommunication network in the United Kingdom based on ‘state of the art’ techniques. Operations have commenced with a leased line service and switching will be introduced in 1985 whilst an international service will commence via satellite during 1984. The wideband capability of digital transmission will enable many new services to be introduced