(Georgia Institute of Technology, 1998)
Bhattacharjee, Samrat; Calvert, Kenneth L.; Zegura, Ellen W.
Multicast video distribution in a best-effort environment presents
challenges to system designers, including heterogeneity in the
bandwidth availability on the paths from the sender to the receivers
and dynamic behavior in the network and set of receivers over time.
Classic approaches to dealing with dynamic conditions involve
adaptation at the sender (for unicast) and adaptation driven by the
receivers (for multicast). Both approaches have limitations that
affect the quality of video received. In this paper, we consider a
third option for the location of adaptation, namely: in the network.
We demonstrate that a modest amount of state and computation at
network routers can yield significant performance gains for multicast
video distribution. Our schemes maintain the advantages of
receiver-based adaptation, while overcoming the limitation. Since the
network applies the adaptation, the time and place for adaptation can
better match network conditions. Further, the adaptation can occur
more rapidly, without the need for route changes. Finally, the
adaptation can occur at finer granularity, providing better quality
and more graceful degradation to receivers.
(Georgia Institute of Technology, 1996)
Bhattacharjee, Samrat; Calvert, Kenneth L.; Zegura, Ellen W.
Active networking offers a change in the usual network paradigm: from
passive carrier of bits to a more general computation engine. The
implementation of such a change is likely to enable radical new
applications that cannot be foreseen today. Large-scale deployment,
however, involves significant challenges in interoperability,
security, and scalability. In this paper we define an active
networking architecture in which user control the invocation of
pre-defined, network-based functions through control information in
packet headers.
After defining our active networking architecture, we consider a
problem (namely, network congestion) that may benefit in the near-term
from active networking, and thus may help justify migration to this
new paradigm. Given an architecture allowing applications to exercise
some control over network processing, the bandwidth allocated to each
application's packets can be reduced in a manner that is tailored to
the application, rather than being applied generically. Our results
show that the ability to gracefully adapt to congestion makes a good
case for active networking.