The widespread deployment of wired and wireless networks in both horizontal
and vertical overlays presents new opportunities and challenges for developers
of services. Users of these networks have multiple end devices, some
of which are mobile, which complicates (and sometimes prevents) the transparent
use of services across the networks. This paper presents an architecture
for enabling the dynamic handoff of active services across multiple networks
(cascaded networks). The architecture supports the rapid development
of innovative new services and enables the use of service- and user-specific
policies for transcoding and routing information between networks.
These policies allow services to determine the "best" mode and route to
use in reachin a particular user. The architecture described in this
paper is being built on top of a campus-wide testbed consisting of GSM
ditital cellular, wireless and wired IP, and public switched telephone
networks. An example application has been constructed to demonstrate
the utility of the architecture.