  In this paper, we present a new technique to obtain upper bounds on
undirected unicast network information capacity. Using this technique, we
characterize an upper bound, called partition bound, on the symmetric rate of
information flow in undirected unicast networks and give an algorithm to
compute it. Two classes of networks are presented for which the bound is tight
and the capacity is achievable by routing thus confirming the undirected
unicast conjecture for these classes of networks. We also show that the bound
can be loose in general and present an approach to tighten it.
