Optical Layer Protection Research Articles

Application of Information Transmission Protocol in Communication Transmission Network System

The biggest advantage of the information transmission protocol is that it has a large-granularity cross-scheduling capability, and uses the information transmission protocol optical add-drop multiplexing equipment (FIROADM) to realize a multi-channel network. Based on the optical cross information transmission protocol network, wavelength-level cross scheduling and signal transmission are realized at the optical layer with the help of G709 standard encapsulation procedure mapping. The information transmission protocol can perform cross-scheduling of end-to-end services at the wavelength level, and the dispatching capability is stronger than that of electrical cross-connections. Moreover, services can run in the optical layer without processing in the electrical layer, and optical cross-connections can achieve flexible networking and support mesh networks. In addition, multiple optical layer protection methods such as optical channels and multiple paths can be constructed as well.

Survivable Hierarchical Optical Path Network Design With Dedicated Wavelength Path Protection

In this paper, we propose a novel network design algorithm that yields the hierarchical optical path network with dedicated wavelength path protection. A hierarchical optical path network provides two granularities in implementing dedicated protection in the optical layer, namely waveband path protection and wavelength path protection. The characteristics of both protection mechanisms are investigated. We develop the concept of the source-destination Cartesian product space to aggregate closely located traffic demands, which leads to a significant reduction in network resources needed. The proposed wavelength path protection algorithm achieves lower network costs than that possible with waveband protection when traffic volume is relatively small. On the other hand, in the large traffic demand area, both schemes offer almost the same cost, which makes the waveband protection scheme attractive because of its operational simplicity. Numerical results clarify that survivable hierarchical optical path network is more cost effective than the single layer optical path network with optical layer protection, irrespective of which protection scheme is utilized.

Frame Loss Evaluation of Optical Layer 10 Gigabit Ethernet Protection Switching Using PLZT Optical Switch System

SUMMARY Frame loss of the optical layer protection switching using Plumbum Lanthanum Zirconium Titanium (PLZT) optical switch is evaluated. Experimental results show that typically 62µs guard time is required for commercially available non-burst mode 10 Gigabit Ethernet modules.

Survivable lightpath provisioning in WDM mesh networks under shared path protection and signal quality constraints

This paper addresses the problem of survivable lightpath provisioning in wavelength-division-multiplexing (WDM) mesh networks, taking into consideration optical-layer protection and some realistic optical signal quality constraints. The investigated networks use sparsely placed optical-electrical-optical (O/E/O) modules for regeneration and wavelength conversion. Given a fixed network topology with a number of sparsely placed O/E/O modules and a set of connection requests, a pair of link-disjoint lightpaths is established for each connection. Due to physical impairments and wavelength continuity, both the working and protection lightpaths need to be regenerated at some intermediate nodes to overcome signal quality degradation and wavelength contention. In the present paper, resource-efficient provisioning solutions are achieved with the objective of maximizing resource sharing. The authors propose a resource-sharing scheme that supports three kinds of resource-sharing scenarios, including a conventional wavelength-link sharing scenario, which shares wavelength links between protection lightpaths, and two new scenarios, which share O/E/O modules between protection lightpaths and between working and protection lightpaths. An integer linear programming (ILP)-based solution approach is used to find optimal solutions. The authors also propose a local optimization heuristic approach and a tabu search heuristic approach to solve this problem for real-world, large mesh networks. Numerical results show that our solution approaches work well under a variety of network settings and achieves a high level of resource-sharing rates (over 60% for O/E/O modules and over 30% for wavelength links), which translate into great savings in network costs.

Low-cost resilience schemes for the Optical Ethernet

"http://www.osa-jon.org/features/OE_2005.html". Feature Issue on Optical Ethernet (OE). Optical Ethernet (OE) architectures transport IP packets directly over the optical layer by providing a specific Layer 2 framing. Although the architectures represent a simple and low-cost solution, the limiting factor for their widespread deployment is represented by the lack of some efficient operation, administration, and maintenance (OA&M) features, such as resilience. Optical layer protection represents a low-cost resilience scheme for OE links. We present the experimental results of low-cost protection implementations that are based on different failure detection and failure protection activation schemes for IP-over-OE networks. Specifically, a dedicated span protection scheme and an evolution for shared protection based on generalized multiprotocol label switching (GMPLS) signaling in transparent domains is presented. Experimental results show that recovery times in the millisecond range are achieved.

Optical layer survivability: a post-bubble perspective

We revisit the topic of optical layer protection from a motivation and deployment perspective. We first discuss the changes that have occurred in optical networking in general and the implications for protection. We then discuss scenarios where optical protection makes sense, recognizing that other fast protection schemes at the client layer provide viable alternatives in certain cases. Our conclusion is that optical protection makes sense for metro networks, as long as they are based on simple dedicated schemes. When it gets to more complex shared ring and mesh protection, we believe that OEO-based schemes are more viable, whether crossconnect-based or packet-switch-based.

Protection approaches for dynamic traffic in IP/MPLS-over-WDM networks

Due to the explosive growth of data-related traffic driven by the Internet, network reliability becomes an important issue. We investigate various protection approaches to handle failures for dynamic traffic demands in IP/MPLS-over-WDM networks. An LSP can be protected at either the IP/MPLS layer or the optical layer. In IP/MPLS layer protection, an LSP is protected by providing a link-disjoint backup LSP between its end nodes. In optical layer protection, an LSP is protected by the backup lightpath of each lightpath traversed by the LSP. We present two integrated routing algorithms: hop-based integrated routing algorithm and bandwidth-based integrated routing algorithm (BIRA) to set up the restorable bandwidth-guaranteed paths efficiently. Then we present a multilayer protection scheme for multiclass traffic in such networks. This scheme takes into account the different QoS and recovery requirements of the traffic to provide protection capability either at the MPLS layer or at the optical layer in a cost-effective manner. We use the connection blocking probability and number of optical-electrical-optical conversions as performance metrics to compare various protection approaches.

Loss-less bridging in 1+1 optical protection using a modified transmitter and receiver

Traditional 1+1 optical layer protection is implemented by creating two signals from one via a 3-dB splitter (with /spl sim/3-dB insertion loss) and transmitting both signals along two different path-diverse optical fibers. In this letter, a transmitter has been modified to provide two signals in such a manner that no excess insertion loss is encountered. Optical protection switching using this transmitter and a modified invertible receiver is demonstrated under 10-Gb/s nonreturn-to-zero transmission. A protection time of 5 ms is obtained.

Optical Layer Protection of ATM Traffics using a Novel 4-Fiber WDM Ring with an Ability to carry Extra Traffic

ATM/IP directly over WDM ring with optical layer protection is proposed and demonstrated. Traffics are 1+1 protected ATM OC-48c and a low priority part-time OC-48c IP traffic. When either fiber or cable failure occurs, optical layer protection can restore the ATM traffic via optical layer span/ring protection within 13 ms/23 ms while the part-time traffic is dropped. A faster protection time comparing with SONET standard is experimentally verified by both physical layer and ATM layer test results.

Optical layer survivability-an implementation perspective

This paper looks at several aspects of optical layer protection techniques from an implementation perspective. We discuss the factors that affect the complexity of optical protection schemes, such as supporting mesh instead of ring protection, handling low-priority traffic, and dealing with multiple types of failures. The paper also looks at how the client layer interacts with the optical layer with respect to protection, in terms of how client connections are mapped into the optical layer, and how protection schemes in both layers can work together in efficient ways. Finally, we describe several interesting optical protection implementations, focusing on the ones that are different from conventional SONET-like implementations.

Optical layer survivability: a services perspective

This article provides a perspective on optical layer protection and restoration based on the services offered by carriers using the optical layer. This is different from other viewpoints that provide a taxonomy of protection techniques in a more abstract fashion for the purposes of standardization. The latter viewpoints are mostly based on the classification adopted in the SONET/SDH standards. In contrast, taking a services-based view provides a way to distinguish between protection schemes based on implementation costs and the associated services enabled by the protection scheme.

A hybrid metropolitan and long-haul WDM network with end-to-end optical channel layer protection performed by metropolitan WDM equipment

We demonstrate a hybrid metropolitan and long-haul wavelength-division multiplexed (WDM) network. In this application, two metropolitan WDM rings are connected to each other by two optically amplified point-to-point WDM transmission systems. The metropolitan WDM equipment performs optical channel layer protection switching when a failure occurs in the metropolitan rings or in the long-haul WDM transport system. This scheme provides an end-to-end protected network for the transport of high-speed data traffic without requiring costly SONET terminals. The protection switching time with this scheme is shown to be much faster than traditional SONET protection times. ©2000 John Wiley & Sons, Inc. Microwave Opt Technol Lett 24: 260–263, 2000.

A hybrid metropolitan and long-haul WDM network with end-to-end optical channel layer protection performed by metropolitan WDM equipment

A hybrid metropolitan and long-haul WDM network with end-to-end optical channel layer protection performed by metropolitan WDM equipment

WDM-based packet networks

We discuss design considerations for wavelength division multiplexing (WDM)-based packet networks. In the near term, such networks are likely to consist of WDM links connected using some form of electronic multiplexing. The focus of this article is on the joint design of the electronic and optical layer with the objective of simplifying the network and reducing the protocol stack. To that end, we discuss the benefits of optical flow switching, network reconfiguration, traffic grooming, and optical layer protection. We also discuss the state of all-optical packet networking with particular focus on local area network technology.