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Introduction

Many characteristics of switched communication networks are directly dependent on how data is relayed over the wires. Early networks carried continuous bitstreams over physical links in a technique called circuit switching, well suited to transmit voice or real time data from a single sender to a single receiver (unicast communication). However, a physical link failure in circuit switching networks has dramatic consequences leading to the interruption of all communications using the failed link. Datagram packet switching networks like the Internet fix these drawbacks by cutting data into small chunks called packets. In datagram packet switching networks, two consecutive packets from the same communication are independently handled by the network. Therefore, when a link fails, packets previously sent on the failed link can be rerouted to avoid the failed link and communications are not interrupted. Datagram packet switching networks are said to be resilient to link failures because link failures are hidden to end-users. On the other hand, it is more difficult to manage end-to-end flows of data in datagram packet switching networks than in circuit switching networks due to the lack of a separate circuit for each flow.

Virtual circuit packet switching, deployed with X.25, Asynchronous Transfer Mode (ATM), and more recently, with Multiprotocol Label Switching (MPLS), keeps the advantages of both circuit and datagram packet switching by sending packets instead of bitstreams over so-called virtual circuits (VC), but also suffers from the same lack of resilience as circuit switching when a link fails. Moreover, techniques have been designed to improve the resilience of unicast communications over datagram packet switching networks, but they are not adapted to multicast communications where one or several senders send traffic to several receivers. This thesis presents a new technique to improve the resilience of multicast communications in virtual circuit packet switching networks.


Subsections
next up previous contents
Next: Switching technology Up: MPLS_trees Previous: List of Tables   Contents
Yvan Pointurier 2002-08-11