Network Admission Control for Fault-Tolerant QoS Provisioning

Abstract

In a connection oriented network layer, admission control (AC) is easily combined with connection state management at each network node. However, after a link or node failure, existing connections are dropped or reservations must be restored on new paths, which requires high signalling effort. In contrast, a connectionless network layer like IP does not deal with connection or resource management at the network nodes. After a failure, connectivity is easily restored by rerouting, affecting higher layer connections only via some packet drops. Thus, a resource management scheme for IP should allow rerouting to cope with failures without affecting reservation states. A network admission control (NAC) handles reservations only at dedicated locations, e.g. the borders of a network, not burdening individual routers with admission decisions or reservation states. The NAC architecture enables resilient resource reservation, maintaining reservations even after failures and intra-domain rerouting. In this paper, we investigate the efficiency of three different distributed budget management schemes with single and multi-path routing. We show how the admission decision can be designed to be tolerable against failure scenarios by admitting only the amount of traffic that can still be carried after a failure and the corresponding rerouting.

This work was funded by the Bundesministerium für Bildung und Forschung of the Federal Republic of Germany (Förderkennzeichen 01AK045) and Siemens AG, Munich. The authors alone are responsible for the content of the paper.