The problems of route optimization, and the sizing of virtual paths and exp
licit routes in wide-area multi-service broadband networks are considered.
The problems are formulated at the call-level in the framework of multi-rat
e, circuit-switched, loss networks, with effective bandwidth encapsulating
cell and packet-level behavior. Broadband networks are characterized by lin
ks with very large capacities in circuits, and are expected to support many
services each having a characteristic bandwidth or rate. Various asymptoti
c results based on Uniform Asymptotic Approximations (UAA) have previously
been obtained to reduce the complexity of the numerical calculations. This
paper offers refinements (RUAA) to UAA to the loss probabilities for a sing
le link, as well as their sensitivities to the offered traffic. Network los
s probabilities are obtained by solving fixed-point equations. Another syst
em of equations determines the implied costs for services and links, which
are used to guide the network optimization. Refined asymptotic approximatio
ns to the network's loss probabilities as well as to the implied costs are
proposed based on the RUAA. The refinements are crucial for the accurate ev
aluations of the implied costs. The complexity of these calculations remain
s bounded as the link capacities and traffic intensities become increasingl
y large, and the complexity for the implied costs is independent of the num
ber of services. A network design tool TALISMAN has been extended to implem
ent the refined approximations. Numerical examples illustrate the accuracy
of the RUAA. (C) 1999 Elsevier Science B.V. All rights reserved.