Synchronous Optical Network/synchronous Digital Hierarchy Research Articles

A Study on Sonet and SDH with their Defects in Optical Network

Background Objectives: Data transmission over a communication channel, should provide important facilities to be added, including data framing, error checking and to manage the channel. Methods/Stastical Analysis: This is a complete review paper and theoretically we intend to explain the basics of SONET / SDH, Architecture, Bit rates, Netowork configurations etc. All these are standardised and approved by ANSI. Conclusion: One would get to know what Synchronous Optical Network / Synchronous Digital Hierarchy (SONET/SDH) is all about and how exactly are they used through this paper. Also, the merits and de-merits are completely analysed.

Optical Power Aware Quality Analysis for the Selection of Optimal OVPN Connection over WDM Network

Traditional optical networks such as synchronous optical network/synchronous digital hierarchy (SONET/SDH) have been perceived as high transmission rate networks without providing any QoS to different connection request. Recently, some attention has been given to coarse-grain QoS using differentiated optical services. Some designs for static VPN have been proposed in literature. However, little research work has been considered to provide dynamic VPN on optical networks. By applying the virtual private network concept to WDM, which is called as Optical Virtual Private Network (OVPN), we explore how to compute a fine-grained QoS for dynamic OVPN connection request based on system components such as connectors, splices, etc. An important problem in WDM network design is to construct an algorithm to determine the optimal OVPN Connection from a set of possible connections in a network topology, which can maximize the quality of service to the OVPN clients. By keeping that in mind, we proposed a method of optimal OVPN selection mechanism based on the traditional power budget analysis.

Optical fiber-wireless access networks: architectures and performance improvements [Series Editorial

The global telecommunications industry continues its transformation in network architectures and services. In the past 10 years, we have seen major shifts in technology innovations from optical transport to last-mile access networks. While synchronous optical network/synchronous digital hierarchy (SONET/SDH) was the center of attention for service providers and their suppliers in the 1980-1995 timeframe, we have witnessed the growth of wavelength-division multiplexing (WDM) to meet bandwidth growth fueled by fiber to the x (FTTx) video and internet service demand starting at about 1995.

Adaptive Reliable Multipath Provisioning in Survivable WDM Mesh Networks

We investigate the problem of adaptive reliable multipath provisioning in next-generation backbone mesh networks employing optical wavelength-division multiplexing (WDM) and channelization techniques such as synchronous optical network/synchronous digital hierarchy (SONET/SDH) and supporting virtual concatenation (VCAT). VCAT enables multipath provisioning, but also introduces differential delay at destination nodes. How to guarantee service availability, using multipath provisioning, and meet the differential-delay constraint (DDC) is an important problem. We introduce the notation M:N(m) for multipath provisioning where a service path for a connection is set up with M primary paths and N backup paths, where each path has a fraction of the bandwidth of the connection, and (m) in this notation denotes “multipath.” With M:N(m) provisioning schemes, we develop an analytical model to analyze the end-to-end connection availability for the full bandwidth request. We propose two types of bandwidth migration methods, which can be implemented by a link-capacity adjustment scheme (LCAS) protocol of next-generation SONET/SDH, to optimize resource usage. Based on the M:N(m) analytical model, we develop an adaptive heuristic algorithm to provision a connection subject to the DDC while satisfying its service-level agreement (SLA). We show that, for end-to-end connection-availability-guaranteed service, multipath provisioning can achieve much better network performance than traditional single-path provisioning. With bandwidth migration, we can further improve multipath provisioning performance.

Integrating optical transport quality, availability, and cost through reliability-based optical network design

The design of the optical transport network (OTN) must meet the challenges of providing a high capacity, highly dependable and reliable network and the flexibility in bandwidth management to support multi-services in a cost-effective manner. The core objective of the OTN design activity focuses on carefully balancing these design objectives. This paper presents a comprehensive design approach that integrates the OTN design with its end-to-end reliability assessment. Quantitative reliability assessment becomes an integral part of the OTN design process when considering network survivability using various protection and restoration schemes. This value-based reliability approach provides a complete set of network reliability profiles. These profiles provide a means to: 1) drive network architecture and infrastructure design by identifying both strong and vulnerable region(s); 2) provide reliability/availability cost and worth (benefit) tradeoff by quantifying the impact of various network elements and/or protection schemes; and 3) allow design of reliability-based revenue offers or service level agreements (SLAs). We will illustrate the application and benefits of using OTN reliability-based design processes in several service provider networks featuring synchronous optical network/synchronous digital hierarchy (SONET/SDH) ring and dense wavelength division multiplexing (DWDM) mesh architectures including dedicated and shared protection/restoration schemes in backbones and in metropolitan networks.

Next-generation transport systems: 4th generation MSPPS

Demand for Ethernet services is increasing exponentially worldwide. Improvements such as generic framing procedure (GFP) and virtual concatenation (VCAT) have been introduced, increasing the efficiency of synchronous optical network/synchronous digital hierarchy (SONET/SDH) transport for packet traffic. The growing volume of packet traffic necessitates further refinement of transport networking techniques toward a more packet-centric model that incorporates increased efficiency in handling packet traffic, and more packet-friendly optical networks; for example, multiprotocol label switching (MPLS) and generalized multiprotocol label switching (GMPLS) enabled networks. The most effective next-generation of multi-service provisioning platforms (MSPPs) must account for these realities and provide a solution for both bandwidth utilization and management capabilities while constituting a platform that can scale from last-mile access to metro core networks. These platforms should incorporate packet-based technologies including MPLS to provide a flexible and cost-effective mix of multi-service traffic engineering and encapsulation techniques, quality of service (QoS), security, and resiliency to providers competing in an increasingly packet-centric market. This paper explains how new transport systems are using novel architectures and exploiting new technologies to support emerging applications with network architectures best suited to the changing characteristics of the traffic they are required to carry.

Optical/packet transport convergence

Today's optical networks are designed to carry fixed-rate telephony and private line traffic in a reliable and resilient manner. Over the last decade, service providers have experienced tremendous growth in data services with the aggregate demand for data traffic now exceeding circuit-oriented traffic. As a result, service providers are challenged to bring their cost structure down so they can generate sustainable margins on competitive services. Lowering the cost structure of data services involves a reduction in capital expenditures, but even more importantly, it necessitates a reduction in operational expenses as well. Global optical/packet transport systems, such as Lucent Technologies' Universal Packet Mux (UPM), are among the network elements addressing this need. They integrate classical synchronous optical network/synchronous digital hierarchy (SONET/SDH) capabilities with multiprotocol label switching (MPLS) transport features on one platform. These new devices can support either connection-oriented or connectionless transport services. This paper describes the applications and value of a new type of universal packet transport system (UPT) for optical/packet networks.

Meeting the broadband access infrastructure demands: The promise of Gigabit Ethernet

Global Internet traffic growth continues to create bandwidth demand in the telecommunications network. As 100 Mb/s Ethernet and Gigabit Ethernet LANs are widely installed in enterprises, the Intranet bandwidth grows quickly. With active adoption of ADSL and cable modem broadband accesses in the SOHO and residential markets, more data traffic is generated in these markets as well. Presently, most telecom carriers use synchronous optical network/synchronous digital hierarchy (SONET/SDH) equipment to “aggregate” data traffic in the metropolitan area network (MAN) before accessing the Internet backbone network. Because of the intrinsic limitations of SONET/SDH equipment in transporting data traffic, especially in terms of bandwidth scalability and provisioning efficiency, there is a need to find a broadband access solution that can overcome the drawbacks of SONET/SDH. Because the inherent simplicity of the technology, Ethernet offers cost effectiveness, ease of networking, packet-based IP friendly protocol, and rapid provisioning advantages while competing with other networking technologies. These advantages coupled with the newly developed gigabit WAN capability have well-positioned Gigabit Ethernet as a compelling technology to break the bandwidth bottleneck in the MAN environment. In this paper, we review the enhancement of Gigabit Ethernet technology and discuss the pros and cons of using Gigabit Ethernet technology in the MAN. We also address the implications of this technology evolution on telecom carriers.

Native 10 Gigabit Ethernet experiments over long distances

The current solutions for transmitting data over Wide Area Networks (WANs) are expensive and require protocol translation at layer 1. The IEEE recently standardized the 10 Gigabit Ethernet (10 GE) WAN PHY as a native gateway from the Local Area Networks (LAN) to the WAN. This opened a debate as to whether Ethernet is now a valid alternative to Synchronous Optical Network/Synchronous Digital Hierarchy (SONET/SDH) for WANs. In this article, we report on the experience gathered while building the first trans-European native 10 Gigabit Ethernet testbed based on WAN PHY. We describe and analyze network tests with a 1700 km Ethernet network. Our work validates this approach and indicates that Ethernet can offer a large bandwidth to long-distance bulk data transfers at a trans-European level.

Creating an intelligent optical network worldwide interoperability demonstration

The Optical Internetworking Forum (OIF) conducted a world interoperability demonstration in conjunction with SUPERCOMM held in Chicago June 22-24, 2004. The demonstration was executed on a global stage with seven carriers across three continents internetworking through an intelligent control plane in a multivendor environment of 15 vendor participants. OIF's demonstration successfully included dynamic end-to-end connection management between client devices and transport network elements in a multidomain, multinode environment. The global connectivity included network elements (NEs) that incorporated the OIF optical user-to-network interface (UNI) and external network-to-network interfaces (E-NNI) among various vendors. Furthermore, carriers were able to test the new Ethernet over synchronous optical network/synchronous digital hierarchy (SONET/SDH) capabilities utilizing the generic framing procedure (GFP-F), virtual concatenation (VCAT), and the link capacity adjustment scheme (LCAS), based on International Telecommunication Union - Telecommunication Standardization Sector (ITU-T) recommendations. This article described the technical approach and execution of this demonstration.

Meeting the broadband access infrastructure demands: The promise of Gigabit Ethernet

Global Internet traffic growth continues to create bandwidth demand in the telecommunications network. As 100 Mb/s Ethernet and Gigabit Ethernet LANs are widely installed in enterprises, the Intranet bandwidth grows quickly. With active adoption of ADSL and cable modem broadband accesses in the SOHO and residential markets, more data traffic is generated in these markets as well. Presently, most telecom carriers use synchronous optical network/synchronous digital hierarchy (SONET/SDH) equipment to “aggregate” data traffic in the metropolitan area network (MAN) before accessing the Internet backbone network. Because of the intrinsic limitations of SONET/SDH equipment in transporting data traffic, especially in terms of bandwidth scalability and provisioning efficiency, there is a need to find a broadband access solution that can overcome the drawbacks of SONET/SDH. Because the inherent simplicity of the technology, Ethernet offers cost effectiveness, ease of networking, packet-based IP friendly protocol, and rapid provisioning advantages while competing with other networking technologies. These advantages coupled with the newly developed gigabit WAN capability have well-positioned Gigabit Ethernet as a compelling technology to break the bandwidth bottleneck in the MAN environment. In this paper, we review the enhancement of Gigabit Ethernet technology and discuss the pros and cons of using Gigabit Ethernet technology in the MAN. We also address the implications of this technology evolution on telecom carriers.

Analyzing jitter at high data rates

Jitter is timing noise that causes bit errors in high-speed data transmission lines. If the data rate of a system is increased, the magnitude of jitter measured in seconds is roughly unchanged, but measured as a fraction of a bit period, it increases proportionally with the data rate and causes errors. Emerging technologies require the ratio of the number of errors to the total number of transmitted bits (the bit error rate, BER) to be less than one in a trillion (10/sup -12/). As datacom, bus, and backplane data rates have increased, many different techniques for characterizing jitter have been introduced, each using a variety of different types of laboratory equipment. To fix difficult jitter problems at high data rates, engineers need to understand the diverse jitter analysis techniques used in both synchronous and asynchronous networking. The article focuses on data rates of emerging technologies above 3 Gb/s. Below 3 Gb/s, real-time oscilloscopes can capture a contiguous data stream that can be analyzed simultaneously in both the time and frequency domains; at higher data rates jitter analysis is more challenging. This discussion is from the perspective of a digital engineer, drawing on the experience of synchronous optical network/synchronous digital hierarchy (SONET/SDH) where many challenges have already been addressed.

The private user network interface - a GMPLS-compliant signaling interface for overlay-based multilayer networks

Feature Issue on Next-Generation WDM Network Design and Routing (WDMN). To address the integration of [IP/MPLS (multiprotocol label-switching)] packet and (optical) transport networks, the Optical Internetworking Forum (OIF) has defined a user-to-network interface (UNI) for overlay networks: the OIF UNI version 1.0, also referred to as the Public UNI. However, since its implementation agreement specification, it has become clear that this UNI--based on OIF-specific extensions to the generalized MPLS (GMPLS) protocols--will not be able to meet the future requirements of some operational environments. Hence a flexible, extensible, and fully GMPLS-compliant UNI is being defined at the Internet Engineering Task Force (IETF): the Private UNI (aka GMPLS for overlay networks). The Private UNI enhances the interaction between the packet and transport network control planes of a multilayer network architecture. This interface is particularly suitable for a control-plane interconnection model in which the equipment belongs to a common administrative entity (i.e., a single carrier environment). Signaling sessions through the Private UNI are used to invoke two main services that require constructive coordination between the network layers: provisioning and network recovery. Here we present the Private UNI specific GMPLS resource reservation protocol-traffic engineering (RSVP-TE) extensions in support of these services in IP/MPLS over SONET/SDH (synchronous optical network/synchronous digital hierarchy) GMPLS multilayer networks and illustrate how Private UNI signaling enhances coordination in multilayer network recovery.

Generalized MPLS-based distributed control architecture for automatically switched transport networks

Current circuit-switched transport networks, such as plesiochronous digital hierarchy (PDH) and synchronous optical network/synchronous digital hierarchy (SONET/SDH), have traditionally used centralized network management for connection control. To facilitate the value-added capabilities of today's networks — such as the rapid provisioning of services, dynamic setup of bandwidth requests, and fast mesh-based restoration — distributed connection control using signaling protocols has quickly gained industry momentum. Efforts have been initiated in various standards bodies to define the automatically switched transport network (ASTN). Although many architectural choices are now available, this paper describes a distributed control plane architecture that can be applied to various circuit-switching technologies and different network applications. This architecture adopts the concept of a generalized version of multiprotocol label switching (MPLS), which extends and modifies MPLS and other protocols on the Internet to make them applicable to various transport networks and also facilitates optical data networking. Four major functional components are incorporated in this architecture: element-level resource discovery, state information dissemination, path selection, and path control modules. Using these concepts, the transport network can be viewed as a virtual nonblocking, reconfigurable backplane of different network clients. This view represents a radical departure from the traditional data networking view of transport networks as providing fixed pipes and will have a dramatic impact on future network interworking and end-to-end traffic engineering (TE).

Intact versus fractional switching in SONET/SDH cross—connects

AbstractSynchronous Optical Network/Synchronous Digital Hierarchy (SONET/SDH) cross connect switching structures may be made non—blocking by providing sufficient hardware resources. For example, in a three—stage Clos switching structure this is accomplished by providing a sufficient number of middle stage switches to allow connections to be made without blocking. Nonblocking SONET/SDH cross—connects are more expensive than architectures which reduce the hardware complexity in their implementations at the expense of increased blocking probability. Under certain circumstances, initially unsuccessful new connections may still be connected if rearrangement of existing connections is possible. Factors which make rearranging connections difficult in a SONET/SDH signal environment is the multirate and multicast nature of the traffic, the requirement that any rearrangements must not interrupt existing sessions, and subnetwork connection protection. Cross—connects with this subnetwork connection protection capability must provide hardware and software functionality that selects between two independent copies of a signal and passes the error—free copy through the matrix. We explain how subnetwork protection introduces a requirement for intact switching of SONET/SDH signals. We also present a comparison of intact and fractional SONET/SDH connection and rearrangement algorithms in the context of subnetwork connection protection requirements. We demonstrate the blocking probability impact of introducing subnetwork protection connections into cross—connects.

Transporting Production/Mastering-Quality Digital Video Signals through the Public Network Using SONET/SDH and ATM Technology

This paper describes a method for transporting a variety of high-quality, standards-based digital video signals through the global synchronous optical network/synchronous digital hierarchy (SONET/SDH) public network infrastructure by using cost-effective, flexible asynchronous transmission mode (ATM) technolog The difficulties of creating nonstandard SONET/SDH tributaries within concatenated synchronous transport signals are bypassed by using ATM-based multiplexing techniques. This approach greatly simplifies the design of SONET/SDH video terminal equipment, while permitting transmission of lower speed data channels along with the high-speed video signals along the SONET/SDH backbone With the use of the techniques described in this paper, any combination of digital video signals can be transported. Finally, due to the extensibility of ATM technology, these production-quality and mastering-quality video signals can be combined with lower speed, compressed video ignals in any feasible mix that does not exceed the maximum backbone bandwidth.