Packet switching method and system with self-routing switch

A packet switching method for use in a packet switching system having a plurality of local switching units each connected to a plurality of packet lines, and a plurality of tandem units each connected to the individual local switching units through at least one transit line having a predetermined transmission capacity, comprising the steps of:

• defining, on each transit line, a plurality of virtual paths each for interconnecting a pair of the plurality of local switching units through one of said tandem units;
• storing, for each transit line, the total value of communication bandwidths assigned to virtual channels which have already been established in virtual paths defined on the transit line;
• checking when a request for setting a new call is received by any particular local switching unit, communication bandwidths of first and second transit lines, on which exists a virtual path to form thereon a virtual channel for said call, to determine whether each transmission capacity of said first and second transit lines has a communication bandwidth portion not yet assigned and whether said portion not yet assigned is wide enough to accept assignment of a bandwidth requested by the call, said first transit line lying between one of said tandem units and said particular local switching unit, and said second transit line lying between said one of said tandem unit and a terminating local switching unit;
• and
• establishing, if said first and second transit lines have a communication bandwidth portion not yet assigned that is wide enough to accept the assignment of the bandwidth requested by said call, said virtual channel for said call on said virtual path and updating the total values of communication bandwidths assigned to said first and second transit lines, respectively.

A packet network comprising:

• a plurality of local switching units each connected to a plurality of packet lines;
• and
• a plurality of transit units each connected to the individual local switching units through at least one transit line having a predetermined transmission capacity;
• each of said local switching units comprises:
• a plurality of first label conversion means each connected to one of said plurality of packet lines and being responsive to a logical channel identifier contained in an incoming packet received from the packet line to add first switching information to said incoming packet,
• a plurality of second label conversion means each connected to one of said transit lines and being responsive to a logical channel identifier contained in an outgoing packet received from the transit line to add second switching information to said outgoing packet,
• a self-routing switch connected to said first and second label conversion mean and operative to switch the incoming packet received from each of said first label conversion means to one of said transit lines selected on the basis of the first switching information contained in the incoming packet and to switch the outgoing packet received from each of said second label conversion means to one of said packet lines selected on the basis of the second switching information contained in the outgoing packet, and
• control means connected to said self-routing switch and operative to terminate a control packet and perform call processing control;
• each of said transit units comprises:
• a plurality of third label conversion means each connected to one of said transit lines and being responsive to a logical path identifier contained in an incoming packet received from the transit line to add third switching information to said incoming packet, and
• a self-routing switch connected to said plurality of third label conversion means and operative to switch the incoming packet received from each of said third label conversion means to one of said transit lines as an outgoing packet on the basis of said third switching incoming packet;
• said control means of each local switching unit comprises:
• means for establishing a plurality of logical paths having bandwidths unfixed in advance between the local switching unit and a desired different local switching unit through different transit units,
• means for managing an available bandwidth for each transit line on which at least one logical path is established, and
• means for checking, when a request for setting a call is originated from any subscriber line connected to the local switching unit, the available bandwidth of a transit line on which a logical path exists on which said call is to be established to determine whether the available bandwidth has a portion not yet assigned and whether the portion not yet assigned is wide enough to accept the assignment of the bandwidth requested by said call and establishing, if said transit lines have the available bandwidth portion not yet assigned that is wide enough, a logical channel for said call on said logical path.

A packet network comprising:

• a plurality of local switching nodes each connected to a plurality of packet lines;
• and
• a plurality of transit nodes respectively connected to the local switching nodes through at least one transit line having a predetermined transmission capacity;
• each of said local switching nodes comprises:
• first means for generating, when a call is originated from any packet line connected to the local switching node, a first control packet containing information indicative of the status of used bandwidth of the transit lines between the local switching node and individual transit nodes and transferring said first control packet to a terminating one of the other local switching nodes for which said call is destined,
• second means for determining, when another first control packet designating the local switching unit as a terminating one and generated by an originating one of the other local switching nodes is received, a pair of first and second transit lines on the basis of the status of used bandwidth of transit lines between the local switching node and the individual transit nodes and information contained in said received first control packet indicative of the status of used bandwidth of transit lines connected to said originating one of the other local switching nodes, said first transit line connecting said originating one of the other local switching node and a particular transit node, said second transit line connecting the local switching node and said particular transit node, and transferring a second control packet containing identification information of said pair of first and second transit lines to said originating one of the other local switching nodes,, and
• third means for establishing, when the local switching node determines said pair of first and second transit lines or another second control packet is received from one of the other local switching nodes serving as the terminating one, a logical channel for said call in a logical path on said pair of first and second transit lines and updating information indicative of the used bandwidth of said first or second transit line having a connection with the switching node.

A packet switching method for use in a packet network having a plurality of local switching units each connected to a plurality of packet lines, and at least one cross-connect unit connected to each local switching unit through at least one transit line having a predetermined transmission capacity, comprising the steps of:

• defining, on each transit line, at least one virtual path for interconnecting at least a pair of said plurality of local switching units through said cross-connect unit, without fixedly assigning communication bandwidth to the virtual path;
• storing, for each transit line, the total value of communication bandwidths assigned to virtual channels which have already been established in the virtual path present on the transit line;
• checking, when a request for setting a new call is originated, communication bandwidths of first and second transit lines, on which exists a virtual path to form thereon a virtual channel for said call, to determine whether the transmission capacity of each of said first and second transit lines can afford to accept assignment of a bandwidth requested by the call, said first transit line lying between said cross-connect unit and an originating local switching unit and said second transit line lying between said cross-connect unit and a terminating local switching unit;
• and
• establishing, if both of said first and second transit lines have an available communication bandwidth portion wide enough to accept the assignment of the bandwidth requested by said call, said virtual channel for said call on said virtual path and updating total values of said communication bandwidths assigned to said first and second transit lines, respectively.

A packet switching method for use in a packet switching system having a plurality of local switching units each connected to a plurality of packet lines, and a plurality of of tandem units each connected to the individual local switching units through at least one transit line having a predetermined transmission capacity, comprising the steps of:

• defining, on each transit line, at least one virtual path for interconnecting at least a pair of the plurality of local switching units through one of said tandem units;
• storing, for each transit line, the total value of communication bandwidths assigned to virtual channels which have already been established in the virtual path defined on the transit line;
• checking, when a request for setting a new call is received by any particular local switching unit, communication bandwidths of first and second transit lines, on which exists a virtual path to form thereon a virtual channel for said call, to determine whether both of said first and second transit lines have an available communication bandwidth portion wide enough to accept assignment of a bandwidth requested by the call, said first transit line lying between one of said tandem units and said particular local switching unit, and said second transit line lying between said one of said tandem unit and a terminating local switching unit;
• and
• establishing, if said first and second transit lines have an available communication bandwidth portion not yet assigned that is wide enough to accept the assignment of the bandwidth requested by said call, said virtual channel for said call on said virtual path and updating the total values of communication bandwidths assigned to said first and second transit lines, respectively.