INTERNETWORK ROUTING USING DIFFERENT SERVICE CATEGORIES FOR ESTABLISHING ALTERNATE ROUTE

摘要

In an inter-PBX routing apparatus, calls fromchannels of different service categories to a destination arenormally carried by a first route. A controller determinesthe available bandwidth remaining in the first route,classifies the channels as a first or second category if theycannot or can tolerated delays when establishing an alternateroute, respectively, or a third category if they do notrequire the second route when the first route is overflowed.A second route is established on a pre-assigned basis when thebandwidth of at least one idle channel of the first categoryis greater than the available bandwidth and on a demand-assignedbasis in response to a request from a channel of thesecond category having a bandwidth greater than the availablebandwidth. When the second route is established, thecontroller controls a switch to establish a path between arequesting channel and the first route if the requestedbandwidth is equal to or smaller than the available bandwidthor a path between it and the second route if the requestingchannel is classified as the first or second category and therequested bandwidth is greater than the available bandwidth.The controller returns a busy tone to the requesting channelif the requested bandwidth is greater than the availablebandwidth.