Patent ID: 6985500

Claim:
A method for the sizing of a deterministic type of packet-switching transmission network serving items of equipment to be interconnected and comprising interconnection nodes connected to one another and to the items of equipment by physical connecting links, this method consisting in setting up a list of the information flows to be conveyed between the different pieces of equipment connected by the network, proposing a network topology assumed to be adapted to the geographical layout of the items of equipment to be connected by the network and to the size of the information flows to be exchanged between the items of equipment, said network topology consisting of the definition of the virtual paths for the transportation of the different information flows and of a meshing of interconnection nodes connected to one another and to the items of equipment by physical connection links that carry these virtual paths, estimating, at each connection node, the maximum delays introduced into the transmissions of the packets by jitter phenomena prompted by themselves and by the connection nodes already crossed by the packets, ascertaining that these maximum delays are compatible with the delays imposed and revising the topology of the network so long as this compatibility is not obtained, wherein, in a network where the packets all have the same speed of transportation V on the physical connection links connecting the interconnection nodes to each other and to the items of equipment, the estimation of the maximum delay times introduced by the jitter phenomenon entails the determining of the jitter component ΔJ K i , added by an interconnection node K at one of its output ports S j linked, by means of a buffer memory receiving a queue and a multiplexing device, with N of its input ports E i , this determination of the component of the jitter ΔJ K , being done when each packet of a virtual path VC i entering the buffer memory by an input port E i has, between an aggregate of packets and the following packet or aggregate of packets, a minimum time interval sufficient to empty the buffer memory to prevent its overflow at the reception of the following packet or aggregate of packets, by the implementation of the following relationship: Δ ⁢ ⁢ J K l = Q V = ∑ l = 1 N ⁢ ⁢ B l - Sup ⁢ { B l } V Q being the maximum quantity of bits of the queue estimated from the relationship: Q = ∑ l = 1 N ⁢ ⁢ B l - Sup ⁢ { B l } N being the number of packet flows liable to converge on the output port considered, namely the number of flows crossing the interconnection node and converging on the output port S j considered, B i being the maximum size in bits of an aggregate of packets likely to reach a VC i by an input port E i , it being possible to express this maximum size also by the relationship: B l =M l ×q max M i being the maximum number of packets in an aggregate of packets capable of arriving at the virtual path VC i through an input port E i and q max being the maximum number of bits of a packet.