Juggler: Virtual Networks for Fun and Profit
Venue
IEEE Transactions on Mobile Computing, vol. 9 (2010), pp. 31-43
Publication Year
2010
Authors
Anthony J. Nicholson, Scott Wolchok, Brian D. Noble
BibTeX
Abstract
There are many situations in which an additional network interface—or two—can
provide benefits to a mobile user. Additional interfaces can support parallelism in
network flows, improve handoff times, and provide sideband communication with
nearby peers. Unfortunately, such benefits are outweighed by the added costs of an
additional physical interface. Instead, virtual interfaces have been proposed as
the solution, multiplexing a single physical interface across more than one
communication endpoint. However, the switching time of existing implementations is
too high for some potential applications, and the benefits of this approach to real
applications are not yet clear. This paper directly addresses these two
shortcomings. It describes a link-layer implementation of a virtual 802.11
networking layer, called Juggler, that achieves switching times of approximately 3
ms, and less than 400 \mu{\rm s} in certain conditions. We demonstrate the
performance of this implementation on three application scenarios. By devoting 10
percent of the duty cycle to background tasks, Juggler can provide nearly
instantaneous handoff between base stations or support a modest sideband channel
with peer nodes, without adversely affecting foreground throughput. Furthermore,
when the client issues concurrent network flows, Juggler is able to assign these
flows across more than one AP, providing significant speedup when wired-side
bandwidth from the AP constrains end-to-end performance.
