ATM communication terminal and ATM communication system

Abstract

A communication terminal and a communication system for efficiently using the transmission capacity of a circuit and reducing the circuits disposed between an ATM switch and communication terminals. The communication terminal disassembles multiplexed signals obtained by multiplexing data into cells of fixed length, adds each of the cells with a header containing destination information and transmits/receives a cell through a communication line. The terminal includes a discriminator for referring to the destination information of each cell to discriminate a cell addressed to the ATM communication terminal, a multiplexed signal generator for multiplexed unit data to be transmitted from the communication terminal to generate a multiplexed signal, a cell-forming unit for forming the multiplexed signal into cells, and a cell re-multiplexed for re-multiplexing the cell generated from the multiplexed data and the cells addressed to the other communication terminal.

What is claimed is:  
     
         1 . A communication terminal which has functions of disassembling multiplexed signals obtained by multiplexing data into cells of fixed length, adding each of the cells with a header containing destination information and transmitting/receiving the cell added to the header through a communication line, comprising: 
 a discriminator for referring to the destination information of each of cells which are received through the communication line to discriminate, with regard to the cells, whether the cell is addressed to the communication terminal concerned (hereinafter referred to as “self communication terminal”) or other communication terminals;    a multiplexed signal generator for multiplexing data to be transmitted from said self communication terminal itself to generate a multiplexed signal;    a cell-forming unit for forming the multiplexed signal generated in the multiplexed signal generator into a cell; and    a cell re-multiplexer for re-multiplexing the cells generated by said cell-forming unit and the cells addressed to the other communication terminals which are discriminated in said discriminator.    
     
     
         2 . The communication terminal as claimed in  claim 1 , further comprising first input and output terminals and second input and output terminals, wherein said communication terminal discriminates and re-multiplexes cells received through said first input terminal through said communication line and then transmits the re-multiplexed cells from said first output terminal, and also discriminates and re-multiplexes cells received through said second input terminal and then transmits the re-multiplexed cells from said second output terminal.  
     
     
         3 . The communication terminal as claimed in  claim 1 , further comprising bypass means for directly transmitting said received cells when abnormality occurs in said communication terminal.  
     
     
         4 . The communication terminal as claimed in  claim 2 , further comprising bypass means for short-circuiting said input terminal and said output terminal to each other when abnormality occurs in said communication terminal.  
     
     
         5 . A communication system comprising n (n represents an integer) communication terminals, each of which has functions of disassembling into cells a multiplexed signal of fixed length obtained by multiplexing data, adding a header containing destination information to each of the cells and then transmitting/receiving the cells through a communication line, wherein each of said communication terminals comprises: 
 a discriminator for discriminating a cell addressed thereto and a cell addressed to another communication terminal by referring to the destination information of the cell received from an input terminal through said communication line;    a multiplexed signal generator for multiplexing data to be transmitted from the self communication terminal to generate a multiplexed signal;    a cell-forming unit for forming the multiplexed signal generated in said multiplexed signal generator into a cell; and    a cell re-multiplexing unit for re-multiplexing the cell which is to be transmitted from said self communication terminal and generated from the multiplexed data, and cells which are discriminated by said discriminator and addressed to the other communication terminals, and transmitting the re-multiplexed cells from said output terminal to said communication line, wherein: 
 the output terminal of a first communication terminal and the input terminal of a second communication terminal in said plural communication terminals are connected via a communication line,  
 the output terminal of an i-th (i represents an integer of 1 or more and (n−1) or less) is connected to the input terminal of an (i+1)-th communication terminal,  
 the output terminal of an (n−1)-th communication terminal is connected to the input terminal of an n-th communication terminal, and  
 the output terminal of the n-th communication terminal is connected to the input terminal of said first communication terminal, whereby a ring-shaped transmission path is constructed among n communication terminals so that data communication can be performed through said transmission path among said n communication terminals.  
   
     
     
         6 . The communication system as claimed in  claim 5 , wherein: 
 said communication terminal further comprises a pair of input and output terminals,    the output terminal of said n-th communication terminal is connected to the (n−1)-th communication terminal, the output terminal of said (i+1)-th communication terminal is connected to the input terminal of said i-th communication terminal, and    the output terminal of said first communication terminal is connected to the output terminal of said n-th communication terminal, whereby a second ring is formed among said n communication terminals.    
     
     
         7 . A communication terminal for disassembling a multiplexed signal obtained by multiplexing data into cells of fixed length, and transmitting/receiving the multiplexed signal through a communication line, comprising: 
 a multiplexed signal generator for multiplexing data to be transmitted from said self communication terminal, thereby generating a multiplexed signal;    a cell-disassembling unit for disassembling the cells received through said communication line to assemble a multiplexed signal; and    a cell multiplexing unit for forming the multiplexed signal assembled and the multiplexed signal generated in said multiplexed signal generator into cells, and transmitting the cells through said communication line.    
     
     
         8 . The communication terminal as claimed in  claim 7 , further comprising a bypass for short-circuiting a reception system and a transmission system of said communication line when abnormality occurs in said communication terminal.  
     
     
         9 . The communication terminal as claimed in  claim 7 , wherein said cell-disassembling unit assembles plural multiplexed signals, and comprises first storage means for storing a first multiplexed signal of the plural multiplexed signals, second storage means for storing a second multiplexed signal, third storage means for storing the multiplexed signal generated in said multiplexed signal generator, fourth storage means for storing the data other than the multiplexed signal to be transmitted from said communication terminal, and read-out control means for controlling the read-out of the multiplexed signals stored in said first to fourth storage means, and wherein said cell multiplexing unit forms the multiplexed signals read out by said read-out control means into cells and transmits the cells thus obtained.  
     
     
         10 . The communication terminal as claimed in  claim 9 , wherein, when a multiplexed signal on a control signal is stored in said second storage means, said read-out control means controls the read-out timing of the multiplexed signal on the control signal stored in said fourth storage means.  
     
     
         11 . The communication terminal as claimed in  claim 7 , further comprising first and second input terminals and first and second output terminals, wherein said multiplexing unit cell-multiplexes the multiplexed signal generated thereby and the multiplexed signal corresponding to the cell received through said first input terminal and then transmitting the cell-multiplexed signal through said first output terminal, and cell-multiplexes the multiplexed signal generated thereby and th multiplexed signal corresponding to the cell signal received through said second input terminal, and then transmits the cell-multiplexed signal through said second output terminal.  
     
     
         12 . A communication terminal having functions of disassembling a multiplexed signal obtained by multiplexing data into cells of fixed length, adding a header containing destination information to each of the cells and transmitting/receiving the cells through a communication line, comprising: 
 a cell-disassembling unit for disassembling cells received through said communication line and assembling a multiplexed signal for every destination information by referring to destination information;    a multiplexed signal generator for multiplexing data to be transmitted from the communication terminal in question;    a re-multiplexing unit for re-multiplexing the multiplexed signal generated in said multiplexed signal generator and the multiplexed signals addressed to other communication terminals in the multiplexed signals assembled; and    a cell-forming unit for forming said re-multiplexed multiplexed signals into cells and transmitting the signals formed into the cells through a communication line.    
     
     
         13 . The communication terminal as claimed in  claim 12 , further comprising first and second input and output terminals, wherein said communication terminal disassembles the cells received from said first input terminal through said communication line and re-multiplexes the multiplexed signals, and transmits the resulting signals from said first output terminal while disassembling the cells received through said second input terminal and re-multiplexing the multiplexed signals and then transmitting the resulting signals from said second output terminal.  
     
     
         14 . The communication terminal as claimed in  claim 12 , further comprising bypass means for directly transmitting the received cells when abnormality occurs in said communication terminal.  
     
     
         15 . A communication system comprising a plurality of communication terminals for disassembling a multiplexed signal obtained by multiplexing data into cells of fixed length and transmitting/receiving the cells through a communication line, wherein: 
 said plurality of communication terminals are connected in series on a communication path,    communication terminals located at both ends in said plurality of communication terminals connected in series are respectively connected to each other through a communication line to form a ring-configuration communication path among said communication terminals, and    each of said plurality of communication terminals assembles a multiplexed signal from cells received through said communication line, and receives a multiplexed signal addressed thereto while cell-multiplexing and transmitting multiplexed signals addressed to other communication terminals and the multiplexed signal obtained by multiplexing data to be transmitted from the communication terminal in question, together with the assembled multiplexed signal.    
     
     
         16 . A communication system comprising a plurality of communication terminals for disassembling a multiplexed signal obtained by multiplexing data into cells of fixed length and transmitting/receiving the cells through a communication line, wherein: 
 said plurality of communication terminals are connected in series to one another on two communication paths which are different from each other in communication direction,    communication terminals located at both ends in said plural communication terminals connected in series through said two communication paths are connected to each other through two communication lines having different communication directions, thereby forming a dual ring-configuration communication path between said communication terminals, and    each of said plurality of communication terminals assembles a multiplexed signal from cells received through said two communication paths, and receives a multiplexed signal addressed thereto while cell-multiplexing and transmitting multiplexed signals addressed to other communication terminals and the multiplexed signal obtained by multiplexing data to be transmitted from the communication terminal in question, together with the assembled multiplexed signal.