ATM switching module suited for system expansion without cell-loss

摘要

In an ATM switching module, expansion interfaces are connected in pair to an ATM switch to respectively operate in active and standby states. When another ATM switching module is installed and a connection is established between an expansion interface of standby state and the newly installed ATM switching module, a process sets the standby state expansion interface in hot-standby state, and holds off incoming ATM cells destined for the hot-standby state expansion interface until the connection is ready to accept cell traffic, whereupon the hot-standby state expansion interface is switched to active state, whereby the ATM switch and an ATM switch of the another switching module constitute a multi-stage configuration. The processor is arranged to update the routing table according to internal state of the ATM switch so that, when a call is to be established for an incoming ATM cell, the header of the cell contains a plurality of fields containing routing data respectively associated with different stages of the multi-stage configuration.