An introduction to optical burst switching

Abstract

Optical burst switching is a promising solution for all-optical WDM networks. It combines the benefits of optical packet switching and wavelength routing while taking into account the limitations of the current all-optical technology. In OBS, the user data is collected at the edge of the network, sorted based on a destination address, and grouped into variable sized bursts. Prior to transmitting a burst, a control packet is created and immediately sent toward the destination in order to set up a bufferless optical path for its corresponding burst. After an offset delay time, the data burst itself is transmitted without waiting for a positive acknowledgment from the destination node. The OBS framework has been widely studied in the past few years because it achieves high traffic throughput and high resource utilization. However, despite the OBS trademarks such as dynamic connection setup or strong separation between data and control, there are many differences in the published OBS architectures. In this article we summarize in a systematic way the main OBS design parameters and the solutions that have been proposed in the open literature.The benefits of optical communication systems have been known for quite awhile, but it was not until the invention of wavelength-division multiplexing (WDM) that the potential of fiber was fully realized. The evolution of WDM optical networks can be classified as shown in Fig. 1, which is similar to the one presented by Gauger et al. [l]. Current WDM networks operate over point-to-point links, where optical-to-electrical-tooptical (OEO) conversion is required at each step. All future WDM designs, however, are focused on all-optical networks (AONs) where the user data travels entirely in the optical domain. The elimination of OEO conversion in AONs allows for unprecedented transmission rates. AONs can further be categorized as wavelength-routed networks (WRNs), optical burst switched networks (OBSNs), or optical packet switched networks (OPSNs). Also, each step of the optical evolution begins with a simpler ring design before moving on to the more general mesh topologies. In the following paragraphs we briefly outline the pros and cons of future all-optical architectures.The AON evolution begins with WRNs, whose operation consists of setting up circuit connections, called lightpaths, between the network nodes. The main constraint of WRNs, typical of all optical communications, is the limited number of wavelengths per fiber. In a larger WRN, for example, this scarce number of wavelengths makes it impossible to create a full mesh of lightpaths between all end users. Consequently, for each WRN topology, network architects have to solve the NP-hard problem of routing and wavelength allocation (RWA) of the lightpaths in order to optimally satisfy the desired user communication. The other challenge of WRNs is their quasi-static nature, which prevents them from efficiently supporting constantly changing user traffic. The proposed signaling protocol for WRNs is generalized multiprotocol la...

On the Capacity of Optical Networks: A Framework for Comparing Different Transport Architectures

“…For such details, we refer the reader to [11]- [14] and references therein. In OBS, all queueing of data occurs in infinite buffers at the access nodes or the end users, as there is no buffering capability in the core.…”

Using the Network Load for Admission Control in OBS Networks: A Multilink Approach

“…Optical Burst Switching (OBS) is an optical data transport technique proposed to ensure the efficient use of the bandwidth offered by Wavelength-Division Multiplexing (WDM) networks [1], [2]. Although optical transmissions can reach the magnitude of terabits per second, electronic switches do not achieve this capacity nowadays.…”

Access Protocols to Support Different Service Classes in an Optical Burst Switching Ring

“…Battestelli and Perras [1] provide a detailed survey on OBS and its variations. There is not much work clone in the field of OBS over metropolitanarea rings.…”