| Abstract: |
We consider the problem of scalable call admission control (CAC) in a DiffServ network and propose a new CAC scheme. Initially, a certain fraction of the bandwidth of the network is reserved
for admission-controlled traffic, and this reservation is carried out according to the hose model, a model that had previously been proposed for VPN provisioning. With this architecture,
admission control can be carried out at edge routers without any need for global coordination. Following the DiffServ philosophy, routers in the core of the network are not involved in CAC or
signaling and do not need to be aware of individual flows. This ensures scalability while offering deterministic bandwidth guarantees. Assuming that different connections create different amounts
of profit for the provider, we consider CAC algorithms that try to maximize the obtained profit. In the on-line version of the problem, we observe that the algorithm by Awerbuch, Azar and Plotkin
can be implemented using local control and achieves a logarithmic competitive ratio. In the off-line version, where all connection requests are known to the algorithm, we give efficient
approximation algorithms achieving good approximation ratios. These algorithms are useful in a scenario with advance reservations. We also give a detailed specification of a possible
implementation of the proposed CAC architecture, and present results of high-level simulations showing the relative performance of different CAC algorithms and the influence of a user model where
users may sometimes be willing to accept an increased price for their connection. |
