Data link control method and system for integrated services digital network

• US 5,051,992 A
• Filed: 11/08/1989
• Issued: 09/24/1991
• Est. Priority Date: 11/11/1988
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Miyazaki, Satoshi, Taniguchi, Hidenobu, Mizuguchi, Keizou, Yagyu, Kazuo, Kawatobi, Tatsuo, Kouyama, Sinichi
• Primary Examiner(s): Safourek, Benedict V.
• Assistant Examiner(s): KIZOU, HASSAN
• Application Number:
  US07/433,198
• Time in Patent Office: 685 Days
• Field of Search: 370/94.1, 370/110.1, 379/93, 379/94, 379/96
• US Class Current: 370/352
• CPC Class Codes: H04Q 11/0428 Integrated services digital network, i.e. systems for transmission of different types of digitised signals, e.g. speech, data, telecentral, television signals

Abstract

There is a communication system comprising: an integrated services digital network (ISDN) having a plurality of information channels (Bch) and at least one control channel (Dch); a CPU (host computer) connected to said ISDN through a communication control processor (CCP); and a plurality of packet terminals connected to the ISDN. In the communication system, when a call request from the CPU or an incoming call request from one of the packet terminals is input to the CCP, if the B channel data link connection or the D channel data link connection for the packets has already been established between the CCP and the ISDN, the CCP selects the channel data link connection as a channel for communication with the packet terminal and multiplexes a plurality of calls to the same channel even if the other space B channels exist.

Claims

1. A data link control method for communication control means connected through at least one subscriber'"'"'s line to an integrated services digital network (ISDN) for providing at least one control channel and a plurality of information channels to each subscriber'"'"'s line, comprising:

a first step of finding, when a call request from a data processor connected to the communication control means or an incoming call request from one of a plurality of terminal means connected to the ISDN is input to the communication control means, an information channel which satisfies such conditions that a data link connection has already been established between the communication control means and the ISDN and a call multiplicity in the information channel is equal to or less than a predetermined threshold value from among a plurality of information channels on the subscribers'"'"' lines connecting the communication control means and the ISDN, and setting the call into said information channel thus found;

a second step of finding, when an information channel which satisfies the conditions in said first step is not found, an information channel in which no data link connection is established yet from among the plurality of information channels, and setting the call in said information channel thus found after a data link connection between said communication control means and said ISDN is established in said information channel; and

a third step of updating the value of the call multiplicity of the information channel in proportion to a number of calls sharing the information channel.

2. A method according to claim 1, wherein said first and second steps are executed in the case where the call request or the incoming call request requires a network connection for packet communication.

3. A data link control method for communication control means connected through at least one subscriber'"'"'s line to an integrated services digital network (ISDN) to provide a plurality of information channels and at least one control channel to each subscriber'"'"'s line, said control channel being constructed by a first control channel for transmitting control signals and a second control channel to transmit information packets, said method comprising:

a first step of comparing, when a call request for packet communication from a data processor connected to said communication control means or an incoming call request from one of a plurality of packet communication apparatuses connected to said ISDN is input to the communication control means, a maximum packet length which is needed by said call with a packet length which can be permitted in said second control channel;

a second step of setting the call into said second control channel if the maximum packet length needed by the call is equal to or less than the packet length permitted in the second control channel, and if a call multiplicity in the second control channel on the subscriber'"'"'s line connecting the communication control means and the ISDN is equal to or less than a first predetermined threshold value;

a third step of finding, if the maximum packet length needed by the call is larger than the packet length permitted in the second control channel, or if the call multiplicity in the second control channel is larger than said first threshold value, an information channel which satisfies such conditions that a data link connection has already been established between the communication control means and the ISDN and the call multiplicity is equal to or less than a second predetermined threshold value from among a plurality of information channels on the subscribers'"'"' lines connecting the communication control means and the ISDN, and setting the call into said information channel thus found;

a fourth step of selecting, if no information channel which satisfies the conditions in said third step is found, an information channel in which no data link connection is established from among a plurality of information channels, and setting the call into said selected information channel after a data link connection between said communication control means and said ISDN is established in said selected information channel; and

a fifth step of changing the value of the call multiplicity regarding the second control channel or the information channel in proportion to a number of calls sharing said second control channel or said information channel.

4. A method according to claim 3, wherein in the case where the call request or the incoming call request designates a channel to which the call should be set, said second step includes a stp of discriminating whether the designated channel can be changed to another channel or not, and if it can be changed, the call multiplicity of said second control channel is compared with the first threshold value.

5. A communication control system connected through at least one subscriber'"'"'s line to integrated services digital network (ISDN) to provide at least one control channel and a plurality of information channels to each subscriber'"'"'s line, comprising:

at least one ISDN adapter means provided in correspondence to said subscribers'"'"' lines;

interface means for communicating with a host apparatus;

processor means for executing a data link control routine in response to a call request from said host apparatus or an incoming call request which is generated from another subscriber'"'"'s apparatus connected to the ISDN and is received by the ISDN adapter means through the control channel on the subscriber'"'"'s line; and

memory means for storing management information of each of the control channel and the information channels on the subscribers'"'"' lines, in which the status of a data link connection on a channel, a current value of a multiplicity of a call which has been set in the channel, and a predetermined multiplicity threshold value which can be permitted on the channel are stored in said memory means for each of the control channel and the information channels,

wherein when said processor means receives the call request or incoming call request for packet communication, the processor means finds an information channel in which a data link connection has already been established between the communication control means and the ISDN and the current call multiplicity value is equal to or less than the threshold value by referring to management information in said memory means and sets the call into said information channel thus found.

6. A system according to claim 5, further comprising:

means for comparing a maximum packet length designated by the call request or incoming call request and an allowable packet length in a packet communication which is executed on said control channel; and

means for setting a call into the control channel if a channel designated by the call request or incoming call request can be changed and the current call multiplicity value in the control channel is equal to or less than the threshold value when it is determined by said comparing means that the designated maximum packet length is equal to or less than the allowable packet length.