Nortel Networks Corporation

Guy L Grenier

Bruce D Keats

A method of detecting signal degrade in an ATM network, and a network element using such method are disclosed. Signal degrade at the ATM layer of the network is detected by monitoring signal degrade at the physical layer of the network. In response, ATM cells indicative of the signal degrade may be generated at the ATM layer, and protection switching may be effected. Preferably, signal degrade at the physical layer may be monitored by determining a bit-error-rate at the physical layer. ATM alarm indication signal ('AIS') cells or ATM protection switching coordination protocol ('CP') cells may be generated to effect the protection switching.

ATM protection switching method and apparatus

A method of switching between groups of working and protection channels/paths in the presence of signal degrade in an ATM network is disclosed. Signal degrade is monitored on a subset of virtual paths (&ldquo;VP&rdquo;s) within a VP group or within a subset of virtual channels within a VC group. If signal degrade is detected on this subset of VPs or VCs, all VPs or VCs within the VPG or VCG are switched from a working entity to a protection entity. Network elements and software embodying such a method are also disclosed.

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Ottawa, Canada

Guy L Grenier