Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04Q—SELECTING
  • H04Q11/00—Selecting arrangements for multiplex systems
  • H04Q11/04—Selecting arrangements for multiplex systems for time-division multiplexing
  • H04Q11/0428—Integrated services digital network, i.e. systems for transmission of different types of digitised signals, e.g. speech, data, telecentral, television signals
  • H04Q11/0478—Provisions for broadband connections
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L12/00—Data switching networks
  • H04L12/66—Arrangements for connecting between networks having differing types of switching systems, e.g. gateways
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L12/00—Data switching networks
  • H04L12/54—Store-and-forward switching systems 
  • H04L12/56—Packet switching systems
  • H04L12/5601—Transfer mode dependent, e.g. ATM
  • H04L2012/5629—Admission control
  • H04L2012/563—Signalling, e.g. protocols, reference model

Definitions

• This invention relates to a method of establishing a virtual circuit between a calling terminal and a destination terminal through a packet switched network 5 and also to a processing system for establishing such a circuit
• the user of the calling terminal supplies details of the destination terminal to a network management operator
• the network management operator then establishes 0 whether a virtual circuit can be provided between the calling terminal and the requested destination terminal For example, if the network management operator decides that the virtual circuit cannot be provided, he advises the user of the calling terminal accordingly It might not be possible to provide the virtual circuit, for example, where the destination terminal is a private intranet or a local area 1 5 network to which the user is denied access There could also be technical reasons which make it impossible to establish the requested virtual circuit.
• network manager refers to equipment which is arranged to perform network management operations. This method of establishing a virtual circuit is inefficient because it involves the use of network management personnel
• a method of 25 establishing a virtual circuit between a calling terminal and a destination terminal through a packet switched network comprising the steps of: transmitting a request for a list of destination terminals from a calling terminal through said network to a processing system connected to said network; returning a list of destination terminals from said processing system 30 through said network to the calling terminal; transmitting an indication of a selected destination terminal from said calling terminal through said network to the processing system; and said processing system establishing a virtual circuit between the calling terminal and the selected destination terminal migraine,
• This invention provides the advantage that a virtual circuit can be established through a packet switched network without involving network management personnel.
• said step of establishing a virtual circuit between the calling terminal and the selected destination terminal comprises the steps of establishing the network addresses of the calling terminal and the selected destination terminal, and using said network addresses to establish the virtual circuit.
• a network management protocol is used to establish the virtual circuit.
• a signalling protocol is used to establish the virtual circuit.
• a processing system for establishing a virtual circuit between a calling terminal and a destination terminal through a packet switched network, said system comprising: a first component for generating a list of destination terminals; and a second component for establishing a virtual circuit through said network; said first component being arranged to supply a list of destination terminals to a calling terminal, to receive an indication of a selected destination terminal from a calling terminal and to supply details of a calling terminal and a selected destination terminal to the second component; the second component being arranged to use details of a calling terminal and a selected destination table received from the first component to establish a virtual circuit through the network between the calling terminal and the selected destination terminal.
• Figure 1 is a block diagram of a public ATM network and a set of terminals connected to the public ATM circuit, together with two private ATM networks and a processing system which are also connected to the public ATM network, which illustrate an embodiment of this invention
• FIG. 2 is a block diagram illustrating the main components of a computer
• Figure 3 is a block diagram of some of the software components of the network intelligence processor shown in Figure 1 ,
• Figure 4 is a flow chart illustrating the sequence of operations which are performed in setting up a virtual circuit through the ATM network of Figure 1 ;
• Figure 5 shows the software components of a modified form of the network intelligence processor of Figure 1 , and
• FIG. 6 is a flow chart illustrating the sequence of operations which are used to establish a virtual circuit through the ATM network of Figure 1 using the modification illustrated in Figure 5
• a public ATM network 10 a set of terminals 1 1 to 1 6 and 1 8 connected to the network 10 and a processing system 1 7.
• Figure 1 also shows a pair of private ATM networks 1 9, 20 connected to the ATM network 10
• the ATM network itself comprises four fully interconnected switches 21 to 24 and two multiplexer/demultiplexers 25 and 26 connected, respectively, to ATM switches 23 and 24.
• all four switches 21 to 24 function as access switches.
• the ATM network 10 shown in Figure 1 is a relatively simple ATM network in that it has only four switches, each of which is an access switch.
• the invention may, of course, be used in an ATM network having a much larger number of switches. In a larger network, some of the access switches may be interconnected by other switches which do not function as access switches.
• an ATM network is a packet switched network in which individual packets take the form of 53 byte cells. Each cell has a five byte header and-.a 48 byte payload. In each cell, the header includes routing information in two fields known as the virtual path identifier (VPI) and the virtual channel identifier (VCI) fields. Often, but not necessarily, the VPI field of a cell provides a coarse level routing while the VCI field provides a fine level routing.
• VPN virtual path identifier
• VCI virtual channel identifier
• the VPI and VCI fields are set to initial values before the cell passes through the ATM input interface.
• the ATM interface may be, for example, the ATM card in a personal computer.
• VPI and/or VCI fields are read and an output port is selected in accordance with the value of one or both of these fields using the routing table contained in the switch Before forwarding the cell on to the selected output port, the values of one or both of these fields are updated.
• routing is controlled in a similar manner For a particular connection between two terminals, the routing tables are established before call commencement Consequently, during a call, two terminals are connected by a virtual circuit
• a virtual cicuit cells carrying data can travel from an originating terminal to a destination terminal and also from an destination terminal to an originating terminal.
• the values in the routing tables for the switches and multiplexers used in the virtual circuit and the initial values of the VPI and VCI fields can be established by network management or by signalling processes Where network management is used, the network manager uses a network management protocol to transmit the initial VPI and VCI fields to the two terminals and also the routing information to the switches and multiplexers which are used in the virtual circuit.
• call set up commences with an originating terminal sending a request for the virtual circuit to the network using a user-network signalling protocol.
• the request is carried in ATM cells between the originating terminal and the network over a signalling virtual channel.
• the virtual circuit is established by signalling messages which use a signalling protocol and pass between the nodes (switches and multiplexers) in ATM cells.
• signalling messages which use the user-network signalling protocol are also carried in ATM cells over a signalling virtual channel.
• the terminals 1 1 1 , 1 2 and 1 5 are personal computers
• the terminal 1 6 is a set-top box for a television set
• the terminal 18 is a video-on-demand (VoD) server
• the terminal 1 3 is an Internet point of presence (POP)
• the terminal 14 is an intranet POP
• the processing system 1 7 comprises a network intelligence processor 31 and a network manager 32.
• connection may be provided by way of a dedicated access line, for example, a twisted copper pair or an optical fibre.
• the computer 1 1 may have a dial-up integrated services digital network (ISDN) connection to the ATM switch 21 .
• ISDN integrated services digital network
• the computer 1 1 may be connected to the ATM switch 21 through a telephone line formed from a twisted copper pair but with the addition of the technology known as asymmetric digital subscriber line (ADSL)
• ADSL symmetric digital subscriber line
• electronic devices at each end of the line cooperate to provide a data transmission channel in addition to an ordinary telephone channel.
• the data channel can deliver 1 .5Mb ⁇ t/s downstream in addition to 1 6kb ⁇ t/s in the upstream direction.
• connection possibilities apply also to the personal computers 1 2 and 1 5
• the connection between it and the ATM multiplexer 26 must be capable of delivering data at a relatively high bandwidth.
• this connection may take the form of an optical fibre or a twisted copper pair provided with ADSL technology.
• connections between the POPs 1 3, 14 the VoD server 1 8, the private networks 1 9, 20, and the network intelligence processor 31 and their associated ATM switches in the public ATM network 10 take the form of high bandwidth dedicated links provided, for example, by optical fibres or coaxial cable.
• the network intelligence processor 31 and the network manager 32 may be connected, for example, through a dedicated link or by way of an X25 channel through the public data network.
• the network manager 32 is connected to the ATM switches 21 to 24 and multiplexerdemultiplexers 25 and 26 and these connections may be through the public data network using X25 channels. Alternatively, these connections may be permanent virtual circuits through the ATM network 10.
• Each of the personal computers 1 1 , 1 2 and 1 5 is of conventional construction and the hardware construction of one of these computers is shown diagrammatically in Figure 2.
• the computer comprises a central processing unit (CPU) 40, storage devices 41 , a visual display unit (VDU) 42, a keyboard 43 and input/output ports 44.
• the storage devices 41 are of conventional form and comprise random access memory (RAM), read only memory (ROM), a hard disk and a floppy disk.
• RAM random access memory
• ROM read only memory
• a hard disk a hard disk and a floppy disk.
• the software applications which control the computer are stored in the storage devices 41 . 6
• the software applications include a communications application which permits the computer to transmit and receive packets using the well known TCP/IP protocols
• the computer can communicate with terminals connected to the public Internet as well as to private intranets
• an ATM card 45 and an associated software application The ATM card 45 together with the software application segment outgoing data packets into ATM cells and reassemble incoming ATM cells into IP data packets.
• HyperText In the World Wide Web (or simply Web) service, information is stored as HyperText
• HTML Mark-up Language
• HyperText Transfer Protocol An Internet server which can supply information using the Web service is known as a Web server and an Internet client which can access such information is known as a Web client.
• a Web client In order to access information using the Web service, a Web client is provided with a software application known as a Web browser.
• a Web browser interprets and displays the information which it receives for display on the computer's VDU
• a Web browser specifies the information it wishes to retrieve using a Uniform Resource Locator (URL).
• URL Uniform Resource Locator
• the software applications include a Web browser.
• the set-top box 1 6 can be connected to a television set for display of video programmes retrieved by the set-top box 1 6 from Internet server or VoD servers.
• the components of the set-top box 16 include a video demodulator unit, a vtdeo decompression unit and a video modulator and also a microprocessor for controlling various other components.
• the set-top box 1 6 includes a Web browser as well as the software applications needed to permit it to receive data using the TCP/IP protocols.
• the Web browser in the set-top box 1 6 may be a cut-down version of a Web browser suitable for a computer. It also has an ATM card and associated software application.
• the POP 1 3 is configured to permit data transmission between the ATM switch 22 and the public Internet Similarly, the POP 14 is configured to permit data transmission between the ATM switch 24 and a private intranet.
• the VoD server 1 8 has an ATM card and associated software. 7
• the network intelligence processor 31 is also constructed as an individual computer and has an internal construction as illustrated in Figure 2. It includes an ATM card and an associated application to permit it to send and receive data from the ATM network 10 As shown in Figure 3, the software applications of the network intelligence processor 31 include a Web server 50, an address translator 51 and an interface 52 The interface 52 permits it to communicate with the network manager 32 The function of the address translator will be described below By way of modification, the network intelligence processor 31 could take the form of a group of individual computers connected together by communication links.
• the computers 1 1 1 , 1 2, 1 5, the set-top box 1 6 and the network intelligence processor 31 are equipped to use the Web service, they may alternatively, or in addition, be equipped to use another higher level protocol service.
• Each of the terminals 1 1 , 1 2, 1 5 and 1 6 is provided with a virtual signalling channel to the network intelligence processor 31 . These channels are established by the routing tables in the ATM switches 21 to 24.
• Each of the terminals 1 1 , 1 2, 1 5 and 1 6 stores the initial VPI and VCI values to access its virtual signalling channel to the network intelligence processor 31 .
• the network manager 32 is constructed as an individual computer and has a hardware construction as illustrated in Figure 2.
• the network manager 32 is arranged to perform standard network management operations. These include monitoring the individual ATM switches 21 to 24 and multiplexer/demultiplexers 25 to 26 and controlling traffic overload.
• the network manager 32 can also establish the routing information needed to provide a virtual circuit and transmit this ⁇ information to appropriate ones of switches 21 to 24 and multiplexer/demultiplexers 25 and 26.
• terminals of ATM networks including terminals 1 1 , 1 2, 1 5 and 16, are not equipped to establish virtual circuits with the use of a user-network signalling protocol.
• the user of the terminal sends details of the required virtual circuit to network management personnel.
• the network management personnel With the aid of a network manager, the network management personnel then establish the virtual circuit. Because this method involves the use of network management personnel, it is inefficient and not suitable for establishing virtual circuits for short periods. 8
• the calling terminal in order to establish a virtual circuit between a calling terminal and a destination terminal, transmits a request to the processing system 1 7 for a list of destination terminals The processing system 1 7 then returns a list of destination terminals to the calling terminal The user then selects a destination terminal and the calling terminal transmits a message containing the identity of a selected destination terminal back to the processing system 1 7 The processing system 1 7 then establishes the required virtual circuit
• an initial step 100 when the user of a calling terminal, for example personal computer 1 1 , wishes to establish a virtual circuit to a destination terminal, for example POP 1 3, the calling terminal sends a request to the network intelligence processor 31 over its signalling virtual circuit for a list of available destination terminals When doing this, the user enters the Web browser application on the calling terminal and the Web browser application is arranged to display an appropriate icon for establishing a virtual circuit.
• the request is received by the Web server 50, which passes it to the address translator 51
• the address translator 51 For each terminal, which might want to establish virtual circuit, the address translator 51 maintains a list of available destination terminals. Each list is stored as a Web page
• the address translator 51 supplies the list of available destination terminals to the Web server 50 which then transmits this list to the calling terminal
• the list also includes transmission options such as quality of service and cell transmission rate.
• the list is displayed as a Web page.
• the user selects the required destination terminal and transmission options and the Web page containing the user's selection is returned to the Web server 50 in the network intelligence processor 31 .
• the returned Web page provides an indication of the destination terminal selected by the user.
• the Web server 50 forwards this Web page to the address translator 51
• the address translator 51 then establishes the network addresses of the calling terminal and the selected called terminal and forwards this information together with the selected transmission options to the interface 52 9
• the interface 52 passes the network addresses and the selected transmission options to the network manager 32.
• the network manager 32 configures the ATM network 10 to provide the requested virtual circuit. In order to do this, it establishes the routing information needed by the switches and multiplexers and transmits this information to the switches and multiplexers. It also informs the destination terminal that a virtual circuit is being established and sends to the destination terminal the VPI and VCI values which it will have to insert into its ATM cells. While the network manager 32 is establishing the virtual circuit, it transmits status information, as may be appropriate, to the network intelligence processor 31 which forwards this information to the calling terminal.
• the network manager 32 sends a message to the network intelligence processor 31 confirming this and also the values of the VPI and VCI required by the calling terminal to send ATM cells over the virtual circuit.
• the network intelligence processor 31 sends a message containing confirmation that the virtual circuit has been established and the initial VPI and VCI values to the calling terminal.
• the software applications of the network intelligence processor comprise the Web server 50 and the address translator 51 and a proxy signalling agent 1 20 in place of the interface 52.
• the proxy signalling agent is a software application on a terminal which is capable of establishing a virtual circuit on behalf of another terminal. In order to do this, the proxy signalling agent uses a user-network signalling protocol.
• the calling terminal for example personal computer
• a step 1 31 the user of the calling terminal selects a destination terminal and the transmission options and a message containing the selection is returned to the network intelligence processor 31 .
• the address translator 51 establishes the network address of the calling and selected called terminals. Then, in a step 1 33, the address translator passes the network addresses and the selected transmission options to the proxy signalling agent 1 20
• the proxy signalling agent 1 20 sends a request to the network 10 to establish the requested virtual circuit with the selected transmission options.
• the requested virtual circuit is established.
• the network 10 sends a message to the network intelligence processor 31 confirming that the network has been configured to provide the virtual circuit and giving the initial VPI and VCI values.
• the network intelligence processor 31 sends a message to the calling terminal which contains confirmation that the virtual circuit has been established and the initial VPI and VCI values required by the calling terminal.

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• Engineering & Computer Science (AREA)
• Computer Networks & Wireless Communication (AREA)
• Signal Processing (AREA)
• Data Exchanges In Wide-Area Networks (AREA)

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• 1999
  • 1999-02-03 WO PCT/GB1999/000364 patent/WO1999041937A1/en not_active Application Discontinuation
  • 1999-02-03 EP EP99903830A patent/EP1060635A1/de not_active Withdrawn

Non-Patent Citations (1)

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