Communication protocol for statistical data multiplexers arranged in a wide area network

Claim 2

A network (10) including at least a transmitting station and a receiving station, the network being characterised by: A. means (86, 14a) at the transmitting station for forming a message (62) containing slot data (70) and a distance field (54) containing a predetermined initial value; B. link means (15) for communicating the message (62) from the transmitting station to the receiving station; and C. means (14b, 85) at the receiving station for receiving the message (62), for incrementing or decrementing the value in the distance field (54), and for forwarding the message (62) along the network.

Claim 3

A network as claimed in claim 1 in which the means (14b, 85) for incrementing or decrementing the value in the distance field (54) and for forwarding the message (62) are arranged to forward the message only if the value in the distance field is not equal to a specified value.

Claim 4

A network as claimed in claim 2 in which the means (86, 14a) for forming the message further includes means for including in the message a destination field (63) whose value is representative of the distance in stations to the destination station; and the means (14b,85) for incrementing or decrementing are arranged to increment the value in the distance field, and then to forward the message only if the values in the distance and destination fields are equal.

Claim 5

A network as claimed in claim 2 in which the predetermined initial value of the distance field (54) is representative of the distance in stations to the destination station; and the means (14b, 85) for incrementing or decrementing are arranged to decrement the value in the distance field, and then to forward the message only if the value of the distance field is zero.

Claim 6

A network as claimed in claim 3 or claim 4 in which a message not for forwarding is determined by the receiving station to be intended for the receiving station, the receiving station further including means for passing on to local associated devices slot data contained within the message.

Claim 7

A network station adapted for interconnection in a network (10) with other network stations (12), the network station being characterised by: A. Assembly means (86, 89) connected to receive slot-data at a plurality of terminal ports (18), and for assembling circuit-specific messages (62) including slot data intended for transmission along the network to one or more terminal ports of a destination network station, each circuit-­specific message (62) including a destination address field (63) and a distance indicator field (54), the destination address field (63) being indicative, in use, of the number of network stations (12) in the network through which the circuit-specific message (62) must pass to arrive at the destination network station (18); B. routing means (86, 83, 14) for routing the circuit-specific messages (62) assembled by the assembly means (86, 89) onto the network; and C. receiving means (82, 84, 85) for receiving circuit-specific messages (62) from the network, for determining whether a given such message is intended for the network station and, if so, for disassembling it into slot-data and passing that data to the terminal ports (18b)

Claim 8

A network station adapted for interconnection in a network (10) with other network stations (12), the network station being characterised by: A. Assembly means (86, 89) connected to receive slot-data at a plurality of terminal ports (18), and for assembling circuit-specific messages (62) including slot data intended for transmission along the network to one or more terminal ports of a destination network station, each circuit-­specific message (62) including a destination address field (63) and a distance indicator field (54), the destination address field (63) being indicative, in use, of the number of network stations (12) in the network through which the circuit-specific message (62) must pass to arrive at the destination network station (18); B. routing means (86, 83, 14) for routing the circuit-specific messages (62) assembled by the assembly means (86, 89) onto the network; and C. receiving means (82, 84, 85) for receiving circuit-specific messages (62) from the network, for determining whether a given such message is intended for the network station and, if so, for disassembling it into slot-data and passing that data to the terminal ports (18b)

Claim 9

A network station as claimed in claim 6 in which the routing means (86, 83, 14) additionally includes: D. means (84b) for comparing the destination field (63) with the distance indicator field (54), and for determining that a circuit-specific message is intended for the network station when the two fields are equal; and E. means for incrementing the distance indicator field (54) when a circuit-specific message (62) is routed to the next neighbouring network station (12) in the network.

Claim 10

A network station as claimed in claim 6 in which the routing means (86, 83, 14) additionally includes: D. means (84b) for comparing the destination field (63) with a given value, and for determining that the circuit-specific message is intended for the network station when the value in the destination field is equal to the given value; and E. means for decrementing the distance indicator field (54) when a circuit-specific message is routed to the next neighbouring network station (12) in the network.

Claim 11

A network station as claimed in any one of claims 6 to 8 in which the routing means (86, 83, 14) additionally includes: F. a plurality of message-forwarding queues (88); G. means, coupled to the assembly means (86, 89) for storing each circuit-specific message (62) in a respective message forwarding queue (88) according to the value of its destination address field (63); and H. means (83a), (83b), coupled to the forwarding message queues (88), for reading circuit-specific messages (62) from successive forwarding message queues (88), and routing the circuit-specific messages (62) so read onto the network.

Claim 12

A network station as claimed in any one of claims 6 to 9 in which the assembly means (86, 89) limits the size of the slot-data so that the maximum message transmission time is equal for all possible message routes in the network.

Claim 13

A network station adapted for interconnection in a network (10) with other network stations (12), the network station being characterised by: A. assembly means (86, 89) connected to receive slot-data at a plurality of terminal ports (18), and for assembling circuit-specific messages (62) therefrom, each circuit-specific message (62) including slot data (70) intended for transmission along the network to one or more terminal ports of a destination network station, each circuit-­specific message (62) including a destination address field (63) and a slot mask (68), the destination field (63) being indicative, in use, of the address of the destination network station (12), and the slot mask (68) indicating which port or ports associated with the destination network station (12) is to receive which portions of the data; B. routing means (86, 83, 14) for routing the circuit-specific messages (62) assembled by the assembly means (86, 89) onto the network; and C. receiving means (82, 84, 85) for receiving circuit-specific messages (62) from the network, for determining whether a given such message is intended for the network station and, if so, for disassembling it into slot-data and passing that data to the terminal ports (18b).

Claim 14

A network station adapted for interconnection in a network (10) with other network stations (12), the network station being characterised by: A. assembly means (86, 89) connected to receive slot-data at a plurality of terminal ports (18), and for assembling circuit-specific messages (62) therefrom, each circuit-specific message (62) including slot data (70) intended for transmission along the network to one or more terminal ports of a destination network station, each circuit-­specific message (62) including a destination address field (63) and a slot mask (68), the destination field (63) being indicative, in use, of the address of the destination network station (12), and the slot mask (68) indicating which port or ports associated with the destination network station (12) is to receive which portions of the data; B. routing means (86, 83, 14) for routing the circuit-specific messages (62) assembled by the assembly means (86, 89) onto the network; and C. receiving means (82, 84, 85) for receiving circuit-specific messages (62) from the network, for determining whether a given such message is intended for the network station and, if so, for disassembling it into slot-data and passing that data to the terminal ports (18b).

Claim 15

A network station as claimed in claim 11 in which the slot mask (68) includes a bit for each of the ports (18) associated with the destination network station for which the circuit-specific message (62) is intended, with a bit set only when the circuit-specific message (62) contains corresponding slot-data (70).

Claim 16

A network station as claimed in claims 11 or 12 in which the circuit-specific message (62) includes a plurality of slot header fields (72), the number of slot header field (72) being equal to the number of slot-data messages (70) in the circuit-­specific message (62).

Claim 17

A network station as claimed in claim 13 in which the slot header fields (72) additionally include a slot message type field (75) containing local area network protocol instructions for exchange between the terminal ports (18).