Network fragmentation occurs when the availability of a resource to an
observer is a function of how the observer is connected to the network. While
fragmentation may be desirable in certain circumstances and for various
reasons, it can also be problematic, violating central Internet design
principles and rendering routine tasks difficult. In the context of the
Internet, network fragmentation is well-known and occurs in many situations,
including an increasing preponderance of network address translation,
firewalls, and virtual private networks. Recently, however, new threats to
Internet consistency have received media attention. Alternative namespaces have
emerged as the result of formal objections to the process by which Internet
names and addresses are provisioned. In addition, various governments and
service providers around the world have deployed network technology that
(accidentally or intentionally) restricts access to certain Internet content.
Combined with the aforementioned sources of fragmentation, these new concerns
provide compelling motivation for a network that allows users the ability to
specify not only the network location of Internet resources they want to view
but also the perspectives from which they want to view them.
The philosophy underlying the Blossom architecture is that access to
Internet resources should be a function of WHO USERS ARE rather than
HOW USERS ARE CONNECTED. Ultimately, systems that seek to provide
end-to-end connectivity will have to accept that unwelcome, perfunctory network
filtering is here to stay. Rather than provide an architecture for
implementing new Internet services, Blossom allows access to existing
resources. In addition, Blossom does not require changes to client or server
applications.
The Blossom software uses Tor for
constructing circuits and transporting data. Blossom uses an alternate network
discovery algorithm and its own directory servers. Unlike Tor directory
servers, Blossom directory servers perform routing, using a policy-enhanced
path-vector protocol. Both Blossom networks and Tor networks consist of
interconnected proxies, but where Tor chooses to optimize for anonymity,
Blossom chooses to optimize for reachability instead. So, Blossom affords users
the ability to specify the perspective from which they want to view the
Internet by sacrificing many of the stronger anonymity benefits of Tor. For
example, unlike the Tor network, the Blossom network allows overlay topologies
that are not fully-connected.
