Routing method and packet switching networks having a distance indicator for routing
First Claim
1. A method of routing packets between first and second bidirectional connection multiplex ways connected to a packet time-division switching network, said network comprising plural packet switches chain-connected to form a bidirectional packet transmission artery, each of said switches connecting to said artery a respective bidirectional connection multiplex way,during a communication set-up phase preliminary to said data packet transmission, activating said first and second connection multiplex ways to transmit in said artery (i) respectively first and second call packets which are disseminated to all said connection multiplex ways so as to measure respectively first and second distances between switches connecting said first and second multiplex ways to said artery, said first and second distances respectively including a number of switches to be crossed by a packet transmitted by said first connection multiplex way to reach said second connection multiplex way and a number of switches to be crossed by a packet transmitted by said second connection multiplex way to reach said first connection multiplex way, and (ii) a call packet including a distance word which is initially set to zero on transmission of said call packet, and incrementing the distance word by 1 as it crosses each switch to provide a measure of said corresponding distance, andduring a communication phase, transmitting data packets including distance words representing said first and second measured distances from said first to second connection multiplex ways and vice-versa so as to carry said data packets, decrementing by 1 a distance word included in a data packet transmitted during the communication phase by 1 as said packet is crossing a switch such that the packet reaches a switch to which a connection multiplex way addressee of said packet is connected, said distance word included in said packet has a null value indicating to said switch that said packet is to be switched to said connection multiplex way connected to it.
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Abstract
A first switching network embodying the invention is a subscriber installation having a chain structure. In the network, the switching is distributed over a plurality of switches each connecting a terminal to the network. A second embodiment is a business network having a star-chain structure and comprising a plurality of sub-networks of chain type. The sub-networks are star connected to central switches which operate in a load sharing mode. According to the method embodying the invention, the terminals connected to the network assume themselves the responsibility for determining communication routes through the network. During a communication set-up phase, caller and callee terminals transmit call packets which are disseminated to all terminals in order to measure two so-called "distances" respectively between the caller and the callee and between the callee and the caller. These distances are after included in data packets for routing said packets.
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Citations
13 Claims
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1. A method of routing packets between first and second bidirectional connection multiplex ways connected to a packet time-division switching network, said network comprising plural packet switches chain-connected to form a bidirectional packet transmission artery, each of said switches connecting to said artery a respective bidirectional connection multiplex way,
during a communication set-up phase preliminary to said data packet transmission, activating said first and second connection multiplex ways to transmit in said artery (i) respectively first and second call packets which are disseminated to all said connection multiplex ways so as to measure respectively first and second distances between switches connecting said first and second multiplex ways to said artery, said first and second distances respectively including a number of switches to be crossed by a packet transmitted by said first connection multiplex way to reach said second connection multiplex way and a number of switches to be crossed by a packet transmitted by said second connection multiplex way to reach said first connection multiplex way, and (ii) a call packet including a distance word which is initially set to zero on transmission of said call packet, and incrementing the distance word by 1 as it crosses each switch to provide a measure of said corresponding distance, and during a communication phase, transmitting data packets including distance words representing said first and second measured distances from said first to second connection multiplex ways and vice-versa so as to carry said data packets, decrementing by 1 a distance word included in a data packet transmitted during the communication phase by 1 as said packet is crossing a switch such that the packet reaches a switch to which a connection multiplex way addressee of said packet is connected, said distance word included in said packet has a null value indicating to said switch that said packet is to be switched to said connection multiplex way connected to it.
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2. A packet time-division switching network comprising I switches, where I is an integer and said switches are chain-connected to form a bidirectional packet transmission artery, each switch connecting a respective bidirectional connection multiplex way to said artery, wherein one of said switches comprises:
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entry means for detecting incoming packets in 3 parallel input multiplex ways, the input multiplex way transmitting the packets synchronously, each incoming packet including a distance word and a signalling bit for indicating a transmission direction of said packet in said artery, said packets including call packets transmitted during a communication set-up phase and data packets transmitted during a data transmission phase of communication, means linked to said entry means for multiplexing said packets transmitted by said entry means; a buffer memory for temporarily storing said packets; means for demultiplexing said packets read cyclically in said buffer memory thereby transmitting them to 3 parallel output multiplex ways; and means for processing the distance word included in each incoming packet and for switching said incoming packet as a function of (i) the signalling bit included in said packet, (ii) whether said packet is a call or data packet, and (iii) the value of said distance word, said distance word representing the number of switches to be crossed by said packet to be routed from a transmission source of said packet to a destination to which said packet is addressed. - View Dependent Claims (3, 4, 5)
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6. A packet time-division switching network comprising J chain-type sub-networks, where J is an integer, and a first central switching means to which said sub-networks are respectively connected by bidirectional connection multiplex ways,
each of said sub-networks comprising I switches, where I is an integer, said switches being chain-connected to form a bidirectional packet transmission artery, each switch connecting a bidirectional connection multiplex way to said artery, first and second of said connection multiplex ways being respectively connected to first and second of said switches respectively included in first and second of said sub-networks, each of said switches comprising: -
entry means for detecting incoming packets in 3 parallel input multiplex ways, the parallel multiplex way transmitting the incoming packets synchronously; each incoming packet including a distance word and a signalling bit for indicating a transmission direction of said packet in said artery, said packets including call packets transmitted during a communication set-up phase and data packets transmitted during a data transmission phase of communication; means linked to said entry means for multiplexing said packets transmitted by said entry means; a buffer memory for temporarily storing said packets; means for demultiplexing said packets read cyclically in said buffer memory and for supplying said cyclically read packets to 3 output multiplex ways; means for processing the distance word included in each incoming packet and for switching said incoming packet as a function of (i) the signalling bit included in said packet, (ii) whether said packet is a call or data packet, and (iii) the value of said distance word, said distance word representing the number of switches to be crossed by said packet to be routed from a transmission source of said packet to a destination to which said packet is addressed; and wherein call packets transmitted by said first and second connection multiplex ways are disseminated through said first central switching means to all said sub-networks, the call packets transmitted by said first and second connection multiplex ways including (i) first and second distance words for respectively indicating first and second distances in said first and second sub-networks, and (ii) a relative address representing switching performed by said first central switching means, said distances and address being included as distance words in said data packets for routing said packets during a communication phase between said first and second connection multiplex ways through said first central switching means. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13)
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Specification