GB1526960A - Communication network - Google Patents

Abstract

1526960 Automatic exchange systems INTERNATIONAL BUSINESS MACHINES CORP 29 Dec 1975 [30 Dec 1974 (5) 26 June 1975] 52959/75 Heading H4K The communications network described in US Specification 4,009,343, includes a management processor for evaluating and controlling the operational effectiveness of traffic connections within the network. The system comprises a plurality of branch exchanges 1À1-1À3, 2À1-2À3, 3À1-3À3, Fig. 1 arranged in geographical groups, each group being connected to a respective network access unit 1-3 of a geostationary satellite communications facility. Each of the branch exchanges and access units include a stored programmed processor with microprocessors being used for the branch exchanges. Digital TDM trunks employing voice activity compression (VAC) interconnect the branch exchanges and the area network access unit. Both duplex telephone lines and data links are served by the system. For other details not relevant to the current invention reference is directed to the above Specification. The management processor NMF referenced 40 in Fig. 8 is connected via a link 41, e.g. a leased public telephone line, to the input of at least one of the branch exchanges 10, the insert also being connected to the processor 34 of the exchanges. Each of the other branch exchanges also have a connection 42 between the processor 34 and the duplex line side of the switching network. Information is transferred directly between the NMF and its local branch exchange processor 34 via the link 41. Information for the network access unit (NAU) processor 12 associated with this branch exchange is transmitted first to the processor 34 and then via the signalling channel 0 of the digital trunk 10À1 to the NAU processor 12. For other geographical areas a normal traffic connection is established between the NMF port and a branch exchange of the remote area, the path including "bootstrap" link 42. Information for the NAU processor of a remote area is relayed via one of its branch exchange processors which sends on the information over the signalling channel of the digital trunk. System initialization for satellite acquisition and for basic traffic connection operations can be achieved in processors 12 of the NAU's using local storage discs and the branch exchange processors are provided with resident microprograms. The NMF is then able to establish connections with all the processors of the system to load programs and tables relating to routing within the system. During normal operation the NMF acts passively and receives from the processors statistics relating to call blocking, freezeout ratio on the digital trunks due to VAC, and call timing information which is used for call billing and for appraisal of network utilization by subscribers. When the statistical reports indicate unusual operation, the NMF may reconfigure the system by reloading the routing information tables in the processors 34,12. In response to excessive freezeout ratio the NMF can instruct any one of the branch exchanges to restrict the number of trunk connections therefrom.