Hybrid Packet and Circuit Data Networks: Design and Operation Issues

Abstract

Experience with packet switching during the past decade has shown that the packet technology is very cost effective for bursty communications between computers and terminals. However, for applications characterized by a steady instead of bursty flow of information (e.g., file transfer, digitized speech, facsimile), it has been established that pure packet protocols are often inadequate because of the unnecessarily high line overhead and the high delay fluctuations between consecutive packets [1]. For such applications, a circuit switching approach (either physical or virtual) appears more advantageous [1],[2]. In the physical circuit approach, bandwidth is dedicated to a connection for the entire duration of the session; while in the virtual circuit approach the path is fixed at the beginning of the session and some expected bandwidth is guaranteed, in a statistical sense, along the path (but no physical bandwidth is assigned).