Virtual LANs (VLANs) permit hosts connected to a LAN switch to be grouped together into logical groups as a function of some management policy rather than simply of their physical location. Commercial LAN switches support a variety of policies based on either physical or logical addresses, protocol types, tagged frames, or user defined rules. The objective of these policies is the same: to reduce the amount of traffic that needs to be routed by grouping together hosts which are likely to communicate with each other into the same virtual LAN. This paper proposes a novel and more direct approach, it shows how VLANs can be created and removed dynamically as a function of the measured traffic patterns across the network. This is both simpler than configuring many static rules and permits the VLAN configuration to adapt to the evolution in the traffic patterns. The latter point is especially important in future LANs supporting peer-to-peer continuous media services, such as IP telephony or video-conferencing, in which clusters of hosts come together to communicate with each other intensively for relatively short periods of time and then form into new clusters.

Abstract:Two hard sub-problems have emerged relating to the use of mobile agents for service management tasks. First, what is their impact on security, and second, how can they receive a flexible capacity to adapt to an open range of different environments on demand, without introducing too stringent prior assumptions.In this paper, we present work towards solving the second problem, which is of particular interest to management software, because it typically needs to excert fine-grained and therefore particular resource control. We suggest a mechanism that reassembles mobile agents from smaller subcomponents during arrival at each hop. The process incorporates patterns of unmutable and mutable sub-components, and is informed by the conditions of each local environment.We discuss different kinds of software adaptation and draw a distinction between static and continuous forms. Our software prototype for dynamic adaptation provides a concept for exchanging environment-dependent implementations of mobile agents during runtime. Dynamic adaptation enhances efficency of mobile code in terms of bandwidth usage and scaleability.

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