The advent of network coding promises to change many aspects of networking. Network coding moves away from the classical approach of networking, which treats networks as akin to physical transportation systems. We overview some of the main features of network coding that are most relevant to wireless networks. In particular, we discuss the fact that random distributed network coding is asymptotically optimal for wireless networks with and without packet erasures. These results are extremely general and allow packet loss correlation, such as may occur in fading wireless channels. The coded network lends itself, for multicast connections, to a cost optimization which not only outperforms traditional routing tree-based approaches, but also lends itself to a distributed implementation and to a dynamic implementation when changing conditions, such as mobility, arise. We illustrate the performance of such optimization methods for energy efficiency in wireless networks and propose some new directions for research in the area.
Optical network Survivability in the backbone, or core, network has been an active area of research. As optics move closer to the edge and to end users, the core network is now used not only to provide connections across a wide area,but also to provide connections for local and metropolitan area networks (LANs and MANs). While optical backbone networks are generally concerned with providing end-to-end circuits based upon whole wavelengths, optical LANS and MANs generally provide shared access to a small number of wavelengths. In this paper, we consider the issue of robustness for optical access networks built as overlays on optical mesh networks. The problem of optical access network robustness is that of maintaining connectivity among nodes of the access networks after a link (or possibly node). We survey three methods of providing robustness to optical access networks. The first method consists of building access networks as covers of rings. The second method builds folded bus overlays and use a combination of optical switches and electronic routers to provide reliability. The third generalizes the concept of buses to build tree-based robust collection and distribution routes over mesh networks.
Optical access networks are beginning to be deployed at the edge of the optical backbone network to support access by the high-end users that drive increased bandwidth demands. This development in the applications of optical networking poses new challenges in the areas of medium access, topology design and network management. In this article, we survey access network architectures and outline the issues associated with providing reliability for these architectures.
All-optical systems are a promising technology for terabit- per-second fiber-optic communication networks. The transmission, switching and routing characteristics of all- optical networks that enable these high rates are intrinsically different from their electro-optic counterparts, particularly when considered with respect to vulnerability to service denial attacks. The characteristics of both components and architecture of all-optical networks appear to have new and little studied security vulnerabilities. Along with those vulnerabilities are a new set of countermeasures which are also different from the electro-optic scenario. This paper addresses the vulnerabilities of all-optical networks to attacks from both inside and outside the network, and present some preliminary results on countermeasures. This work concentrates on physical security differences between all-optical networks and more conventional electro-optic networks with a goal of understanding the differences in attack mechanisms. These difference suggest new countermeasures that may significantly reduce the infrastructure vulnerability of all-optical networks. The work is timely in that consideration of the physical security of all-optical networks in a way that will be difficult to match using post-deployment techniques.
High speed optical communications systems are evolving rapidly. Commercial systems achieve high aggregate data rates utilizing wavelength division multiplexing, where multiple wavelength channels carry information at electronic rates, typically 2.5 Gb/s. Data encryption in these systems will most likely be implemented electronically. However, future system may also utilize time division multiple access (TDMA) schemes and technologies for 100 Gb/s, single stream TDMA networks are currently being developed. These high speed TDMA networks will rely on all-optical switches and processors to interface the high-speed electronics in the users nodes to the ultra-high-speed optical data bus. Data encryption in these networks may need to be implemented using optical logic gates. Straightforward duplication of electronic encryption circuits using optical logic gates is not feasible because optical logic gates have low fan-out, require high optical powers, are difficult to synchronize and have high latency. In this paper, we propose a high- speed electro-optic scheme for reconfigurable feedback shift registers (RFSRs) that relies upon electronic encryption circuits to reconfigure a sequence of optical logic gates and which makes use of the latency in the optical gates as memory. We show that, for linear RFSRs, the low number of optical gates is not a drawback and that the period of the sequences is generally very large. Non-linear feedforward functions, such as all-optical bit swapping, many also be introduced to improve the pseudo-random properties of the sequences.
Conference Committee Involvement (6)
Optical Transmission Systems and Equipment for Networking VI
11 September 2007 | Boston, MA, United States
Optical Transmission Systems and Equipment for Networking V
2 October 2006 | Boston, Massachusetts, United States
Optical Transmission Systems and Equipment for WDM Networking IV
25 October 2005 | Boston, MA, United States
Optical Transmission Systems and Equipment for WDM Networking III
25 October 2004 | Philadelphia, Pennsylvania, United States
Optical Transmission Systems and Equipment for WDM Networking II
8 September 2003 | Orlando, Florida, United States