Performance Analysis of an RSVP-Capable Router

RSVP is a bandwidth reservation protocol that allows distributed real-time applications such as video-conferencing software to make bandwidth reservations over packetswitched networks. Coupled with real-time scheduling mechanisms built into packet routers, the network guarantees to provide the reserved bandwidth throughout the lifetime of the applications. Although guaranteed services are of great value to both end users and carrier providers, their performance cost, due to additional control and data processing overhead, can potentially have a negative impact on the packet throughput and latency of the RSVP-capable routers. The goal of this paper is to examine the performance cost of RSVP based on measurements from an industry-strength RSVP implementation on a commercial IP router. The focus is on the detailed evaluation of the performance implications of various architectural decisions in RSVP, as well as the e ectiveness of RSVP in the presence of network faults. We found that RSVP's control messages do not incur signi cant overhead in terms of processing delay and bandwidth consumption. However, the performance overhead of real-time packet scheduling is noticeable in the presence of a large number of real-time connections. In extreme cases, the performance guarantees of existing real-time connections may not be kept, and some best-e ort packets are actually dropped, although the overall bandwidth requirement from these connections is smaller than the available link bandwidth. 1The research was supported by a student grant from Reuters Information Technology, Inc.