An energy-aware solution for physical-layer reconfigurability in metro-access networks is presented. The dynamicity of optical switching is introduced in nodes that are perceived as fully-passive by the network. Energy scavenging at low optical feed level of -10dBm supports field-deployment without local electrical power supply. Two types of network nodes are demonstrated experimentally. First, a resilience node is evaluated for fast protection switching in 10.7 ms at the feeder segment. Optical switching is further exploited for the purpose of dynamic allocation of spectral slices and routing in a new class of reconfigurable optical add-drop multiplexer. The spectral bandwidth of drop segments can be extended on demand while intranetwork communication among different segments of the access network is also enabled. Finally, we discuss the potential for realizing self-powering by means of tapping optical signals traversing the access network rather than utilizing a dedicated pump source.

A flash crowd event can be characterised by a dramatic increase in requests for a service over a relatively short period of time. Often, these events lead to a loss of service because of the saturation of the target server and associated network resources. This paper presents a set of mechanisms that can be used to make Web servers and associated resources more resilient to flash crowd events. Specifically, we present a novel admission control mechanism that uses a detection mechanism we developed in earlier work to adjust the admission rate of HTTP requests to a Web server. We demonstrate, via simulations, that the admission control mechanism can be used to protect a Web server from the effects of a flash crowd event, protect the traffic of other services that are hosted on the same network as a targeted Web server, and in combination with a push-back mechanism reduce the effect of flash crowd traffic on an ISP's network that is serving the Web server. The mechanisms presented here are exemplars that fit within a resilience strategy we are developing - D2R2+DR - which is summarised here.

The integration of distributed multimedia systems around the unifying theme of quality of service (QOS) is addressed. A set of key QOS requirements is presented and mapped onto a provisional QOS architecture (QOS-A) that has emerged from a experimental system designed and implemented at Lancaster. The scope of the discussion is limited to aspects of a QOS-A for the support of continuous media communications. Also, the focus is on asynchronous transfer mode (ATM) at the network layer rather than the full range of multiservice networks. Functions and mechanisms for QOS support are examined and placed within the evolving QOS-A.>