The Julia Content Distribution Network

Peer-to-peer content distribution networks are
currently being used widely, drawing upon a large fraction
of the Internet bandwidth. Unfortunately, these applications
are not designed to be network-friendly. They optimize
download time by using all available bandwidth. As a
result, long haul bottleneck links are becoming congested
and the load on the network is not well balanced.
In this paper, we introduce the Julia content distribution
network. The innovation of Julia is in its reduction of the
overall communication cost, which in turn improves network
load balance and reduces the usage of long haul links.
Compared with the state-of-the-art BitTorrent content distribution
network, we find that while Julia achieves slightly
slower average finishing times relative to BitTorrent, Julia
nevertheless reduces the total communication cost in the
network by approximately 33%. Furthermore, the Julia
protocol achieves a better load balancing of the network
resources, especially over trans-Atlantic links.
We evaluated the Julia protocol using real WAN deployment
and by extensive simulation. The WAN experimentation
was carried over the PlanetLab wide area testbed
using over 250 machines. Simulations were performed
using the the GT-ITM topology generator with 1200 nodes.
A surprisingly good match was exhibited between the
two evaluation methods (itself an interesting result), an
encouraging indication of the ability of our simulation to
predict scaling behavior