System for internetworking data terminal equipment through a switched digital network

• US 5,459,720 A
• Filed: 03/31/1994
• Issued: 10/17/1995
• Est. Priority Date: 12/23/1991
• Status: Expired due to Term

• Current Assignee: Enterasys Networks Incorporated (Extreme Networks, Inc.)
• Original Assignee: Network Express, Inc.
• Inventors: Butler, Timothy, DeVries, Paul A., Carson, David J., Iliev, Simeon
• Primary Examiner(s): Hsu, Alpus
• Application Number:
  US08/220,951
• Time in Patent Office: 565 Days
• Field of Search: 370/54, 370/55, 370/58.1, 370/58.2, 370/58.3, 370/60, 370/60.1, 370/66, 370/68, 370/68.1, 370/84, 370/94.1, 370/112, 370/118, 370/79, 370/82, 370/83, 370/99, 370/110.1
• US Class Current: 370/393
• CPC Class Codes: H04J 3/1647 Subrate or multislot multiplexing
• CPC Class Codes: H04L 12/2854 Wide area networks, e.g. public data networks
• 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
• CPC Class Codes: H04Q 2213/1302 Relay switches
• CPC Class Codes: H04Q 2213/1304 Coordinate switches, crossbar, 4/2 with relays, coupling field
• CPC Class Codes: H04Q 2213/13093 Personal computer, PC
• CPC Class Codes: H04Q 2213/13096 Digital apparatus individually associated with a subscriber line, digital line circuits
• CPC Class Codes: H04Q 2213/13103 Memory
• CPC Class Codes: H04Q 2213/13106 Microprocessor, CPU
• CPC Class Codes: H04Q 2213/13208 Inverse multiplexing, channel bonding, e.g. TSSI aspects
• CPC Class Codes: H04Q 2213/13209 ISDN
• CPC Class Codes: H04Q 2213/13299 Bus
• CPC Class Codes: H04Q 2213/1332 Logic circuits
• CPC Class Codes: H04Q 2213/13322 Integrated circuits
• CPC Class Codes: H04Q 2213/13333 Earth satellites
• CPC Class Codes: H04Q 2213/13389 LAN, internet

Abstract

A System including device access, network access system management, and related method for providing users who have require aperiodic high bandwidth data transmission requirements between remote sites access over a public switched digital network of a conventional type is disclosed. The invention uses a scheme of inverse multiplexing by which it first logically splits a high bandwidth information stream into multiple narrow band signals for transmission through public switched digital network over a plurality of narrow band channels to be received at the remote location by another Switched Network Access System then recombined to form the original high bandwidth information stream causing the multiple narrow band channels to appear as a single high bandwidth channel to remote high bandwidth end users. The Switched Network Access System provides automatic bandwidth allocation and agility which optimizes throughput and reduces data communications costs by adding or dropping narrow band channels "as needed" based on user bandwidth utilization.

Claims

1. A method for transmitting high bandwidth messages between remote communication stations connected by a switched digital network, comprising the steps of:

A. establishing, at a sending communication station, a plurality of communication connections through said switched digital network to a receiving communications station wherein the bandwidth of a first one of said plurality of communication connections is smaller than the bandwidth of a second one of said plurality of communication connections;

B. forming each of said messages into one or more packets of digital data;

C. dividing each of said packets into a plurality of sub-packets;

D. transmitting from said sending communications station said plurality of sub-packets through said plurality of communication connections to said receiving communication station, including transmitting a first one of said sub-packets through said first communication connection, selectively transmitting a second one of said sub-packets through said second communication connection, and transmitting the remaining ones of said sub-packets through preselected ones of said communication connections;

E. receiving said plurality of sub-packets at said receiving station;

F. reassembling each of said plurality of sub-packets into packets at said receiving station,

G. deleting said plurality of communication connections.

2. The method of claim 1 wherein steps (B) and (C) are performed at said sending communication station.

3. The method of claim 1 wherein step (A) includes the steps of:

H. monitoring the capacity of said communication connection to transmit said packets, and

I. establishing additional ones of said communication connection when the monitored capacity falls below a preselected value.

4. The method of claim 3, including the step of deleting at least certain of the communication connections in step (A) when the monitored capacity exceeds a preselected value.

5. The method of claim 1, including the step of appending routing information to each of said packets.

6. A method of transmitting digital data information in the form of data packets having a preselected sequence representing a message using a switched digital network including a plurality of communication lines from a calling user terminal to a receiving user terminal, wherein each of the lines includes one or more channels through which the data packets may be transmitted, comprising the steps of:

(A) establishing one or more communication connections from said calling user terminal to said receiving user terminal by selecting one or more of said communication lines;

(B) monitoring the bandwidth utilization of each of said channels through which a communication connection has been established in step (A);

(C) establishing additional communication connections from said calling user terminal to said receiving user terminal when said utilization of the channels monitored in step (B) exceeds a first predetermined value to thereby increase the bandwidth available for transmitting the data packets;

(D) disconnecting at least certain of said communication connections established in steps (A) and (C) when said utilization of the channels monitored in step (B) falls below a second predetermined value; and

(E) transmitting said data packets over the channels through said communication connections established between the calling user terminal and the receiving user terminal.

7. The method of claim 6 wherein step (E) is performed through a plurality of communication connections.

8. The method of claim 7, further including the step of:

appending to each of said data packets sequencing and routing information including identification of the receiving user terminal.

9. The method of claim 8, further including the steps of:

receiving at said receiving user terminal the packets transmitted in step (E); and

sequencing said received packets in accordance with said sequencing and routing information to form the message.

10. The method of claim 8, further including the steps of:

dividing each of the data packets into a plurality of sub-packets for transmission from said calling user terminal to said receiving user terminal; and

appending to each of said sub-packets said sequence and routing information.

11. The method of claim 10, wherein step (E) is performed by the substeps of:

transmitting a first one of said plurality of sub-packets on a first one of said plurality of communication connections; and

transmitting a second one of said plurality of sub-packets on a second one of said plurality of communication connections and transmitting the remaining ones of said sub-packets through said communication connections.

12. The method of claim 11, further including the steps of:

receiving at said receiving user terminal said plurality of sub-packets; and

sequencing said sub-packets in accordance with said sequence and routing information to form each of said data packets.

13. The method of claim 12, further including the step of:

sequencing the data packets formed by said received sub-packet sequencing step to form the message.

14. The method of claim 7, wherein a first one of said plurality of communication connections is over a first one of said plurality of communication lines, and a second one of said plurality of communication connections is over a second one of said plurality of communication lines.

15. The method of claim 8, further including the steps of:

assigning said data packets to certain time slots on a time division multiplex highway; and

switching said data packets from said time division multiplex highway into available channels on said plurality of communications connections to thereby optimize bandwidth utilization of said communication connections.

16. The method of claim 11, wherein said first one of said communication connections is over a first one of said plurality of communication lines, and said second one of said communication connections is over a second one of said plurality of communication lines.

17. The method of claim 12, further including the steps of:

assigning said sub-packets to certain time slots on a time division multiplex highway; and

switching said sub-packets from said time division multiplex highway into available channels on said plurality of communications connections to thereby optimize bandwidth utilization of said communication connections.

18. A method of conveying digital data information in the form of data packets having a preselected sequence representing a message from a calling user terminal to a receiving user terminal connected by a switched digital network including a plurality of communication lines, wherein each of the lines includes one or more channels through which the data packets may be transmitted, comprising the steps of:

(A) establishing a first communication connection from said calling user terminal to said receiving user terminal through a first one of said communications lines by selecting a first available channel on said first communication line;

(B) searching for a second available channel on said first communication line;

(C) establishing a second communication connection from said calling user terminal to said receiving user terminal through said first communication line when a second available channel is found in step (B);

(D) establishing a second communication connection from said calling user terminal to said receiving user terminal through a second one of said communication lines when a second available channel is not found in step (B);

(E) dividing each of said data packets into a plurality of sub-packets;

(F) appending sequencing and routing information including identification of said receiving user terminal to each one of said sub-packets;

(G) transmitting a first one of said plurality of sub-packets through said first communication connection;

(H) transmitting a second one of said plurality of sub-packets through said second communication connection, and transmitting the remaining ones of said plurality of sub-packets through said plurality of lines;

(I) receiving said plurality of sub-packets at the receiving user terminal through said first and second communication connections; and

(J) reassembling said received sub-packets into the data packets in accordance with said sequencing and routing information at said receiving user terminal to form the message.

19. The method of claim 18, further including the steps of:

monitoring the bandwidth utilization of each of the channels through which a communication connection has been established in steps (A), (C), and (D); and

establishing additional communication connections from said calling user terminal to said receiving user terminal when said utilization of the channels monitored in said monitoring step exceeds a first predetermined value to thereby increase the bandwidth available for transmitting the data packets.

20. The method of claim 19, further including the step of:

disconnecting at least certain of said communication connections established in steps (A), (C), and (D) when said utilization of the channels monitored in said monitoring step falls below a second predetermined value.

21. The method of claim 20, further including the steps of:

determining the bandwidth of each of said channels through which a communication connection has been established between the calling user terminal and the receiving user terminal; and

segmenting each of said data packets into a plurality of sub-packets the size of said sub-packets corresponding to the size of the bandwidth of each of the channels determined by said bandwidth determining step.

22. The method of claim 21, further including the steps of:

assigning said sub-packets to certain time slots on a time division multiplex highway; and

switching said sub-packets from said time division multiplex highway into said channels through which a communication connection has been established from the calling user terminal to the receiving user terminal to optimize bandwidth utilization of said communication connections.

23. The method of claim 21, wherein a first one of said plurality of sub-packets has a first size, a second one of said plurality of sub-packets has a second size, said first size being larger than said second size.

24. An apparatus for conveying data messages in the form of packets having a preselected sequence representing a message from a calling user terminal to a receiving user terminal using a switched digital network of the type including a plurality of communication lines, wherein each of the lines includes one or more channels through which the data packets may be conveyed, comprising:

means for controlling the conveyance of said packets, said controlling means including a central processor;

means coupled with said controlling means for accepting said packets from a calling user terminal, said accepting means including a device access processor;

means responsive to said controlling means for selecting one or more communication lines for establishing a plurality of communication connections from said calling user terminal to said receiving user terminal and for disconnecting at least certain of said communication connections, said selecting means including a call control processor;

means coupled with said controlling means for monitoring the bandwidth utilization of each of said channels through which said plurality of communication connections have been established, said selecting means establishing additional communication connections from said calling user terminal to said receiving user terminal responsively when said utilization of the channels monitored exceeds a first predetermined value and disconnecting at least certain of said communication connections when said utilization of the channels monitored falls below a second predetermined value, said monitoring means including said central processor coupled with a multi-channel protocol unit; and

means coupled with said controlling means for transmitting said packets over the channels through which said plurality of communication connections have been established, said controlling means being operative to forward said data packets accepted by said accepting means to said transmitting means, said transmitting means including at least one line interface unit.

25. The apparatus of claim 24, further comprising:

means responsive to said controlling means for appending a first header, at said calling user terminal, to each of the data packets, said first header comprising sequencing and routing information, including identification of the receiving user terminal, said appending means including a data link controller;

said transmitting means being coupled with appending means, said transmitting means transmits a first one of said data packets over a first one of said channels through which said plurality of communication connections have been established by said selecting means, and transmits a second one of said data packets over a second one of said channels through which said plurality of communication connections have been established by said selecting means;

said transmitting means being operative to receive data packets having a second header originating from said receiving user terminal through the communication lines; and

means coupled with said controlling means and coupled with said transmitting means for arranging the data packets received by said transmitting means in accordance with said sequencing and routing information contained in said second header, said arranging means including a direct memory controller.

26. The apparatus of claim 24, further comprising:

means coupled with said controlling means for dividing each of said data packets into a first plurality of sub-packets, said dividing means including a data link controller;

means responsive to said controlling means for appending a first header, at said calling user terminal, to said first plurality of sub-packets, said first header comprising sequencing and routing information, including identification of the receiving user terminal, said appending means including said data link controller responsive to said multi-channel protocol unit;

said transmitting means being coupled with said appending means, said transmitting means transmits a first one of said first plurality of sub-packets over a first one of said channels through which said communication connections has been established, and transmits a second one of said first plurality of sub-packets over a second one of said channels through which said communication connections have been established, and transmits the remaining ones of said first plurality of sub-packets over said channels through which said communication connections have been established;

said transmitting means being operative to receive a second plurality of sub-packets originating at said receiving user terminal, each one of said sub-packets having a second header, through the communication lines; and

means coupled with said controlling means and said transmitting means for arranging said second plurality of sub-packets in accordance with said sequencing and routing information contained in said second header, to form a data packet in which the sequence of data bits is the same as that of the data packet originating at the receiving user terminal from which said second plurality of sub-packets was originally derived.

27. The apparatus of claim 26, wherein said dividing means includes:

means for determining the bandwidth of each of said channels through which said plurality of communication connections has been established; and

means coupled with said bandwidth determining means for segmenting each of said data packets into a first plurality of sub-packets the size of said sub-packets corresponding to the bandwidth of each of the channels determined by said bandwidth determining means.

28. The apparatus of claim 27, further including:

means coupled with said controlling means for assigning said first plurality of sub-packets to certain time slots on a time division multiplex highway, said assigning means including said central processor responsive to said a path management unit, and further including said data link controller; and

means coupled with said controlling means and said transmitting means for switching said first plurality of sub-packets from said time division multiplex highway into the channels through which said plurality of communication connections has been established by said selecting means, said switching means including a switch.

29. The apparatus of claim 27 wherein a first one of said plurality of sub-packets has a first size, a second one of said plurality of sub-packets has a second size, said first size heine larger than said second size.

30. An apparatus for use in conveying data messages in the form of packets from a calling user terminal to a receiving user terminal using a switched digital network having a plurality of communication lines, wherein each of the lines includes one or more channels through which the packets may be conveyed, comprising:

a system management processor including means for controlling multi-channel communications;

device access means coupled with said system management processor and with said calling user terminal for accepting packets;

network access means coupled with said system management processor and said plurality of communication lines for transmitting said packets from said calling user terminal and receiving packets transmitted from said receiving user terminal, said system management processor being operative to forward said packets from said device access means to said network access means,

said network access means including a call control processor responsive to said system management processor for establishing on available channels a plurality of communication connections between said calling user terminal and said receiving user terminal and for disconnecting at least certain of said plurality of communication connections,

said network access means further including a controller, coupled to said system management processor for receiving said packets originating at said calling user terminal,

said controller including a means, responsive to said means for controlling multi-channel communications, for segmenting each of said packets into a plurality of sub-packets,

said controller including a means, responsive to said means for controlling multi-channel communications and connected to said segmenting means, for appending a header to each one of said plurality of sub-packets, said header containing sequencing and routing information,

said controller being operative to transmit a first one of said plurality of sub-packets having said header through a first one of said communication connections and a second one of said plurality of sub-packets through a second one of said communication connections and the remaining ones of said plurality of sub-packets through said communication connections, said system management processor signals call control processor to establish said first and second ones of said communication connections on a first one of said communication lines when channels are available on said first one of said communication lines.

31. The apparatus of claim 30 wherein said means for controlling multi-channel communications monitors the bandwidth utilization of each of the channels through which a communication connection has been established by said call control processor,

said means for controlling multi-channel communications signals said call control processor via said system management processor to establish a further communication connection between the calling user terminal and the receiving user terminal when said utilization of the channels monitored exceeds a first predetermined value,

said means for controlling multi-channel communications signals said call control processor via said system management processor to disconnect at least certain of said communication connections when said utilization of the channels monitored falls below a second predetermined value,

said system management processor, being responsive to said means for multi-channel communications, changes the number of communication connections in response to bandwidth utilization.

32. The apparatus of claim 31, wherein said network access means further includes:

a time-division multiplex highway having a plurality of time slots, said highway coupled to said controller, wherein said controller transmits the packets onto selected time slots of said highway;

a switch for routing selectively the packets, said switch being coupled to said highway; and

a line interface for interfacing said switch to the communication lines of the switched digital network, said line interface being connected to said switch,

wherein said packets on said selected time slots of said highway are routed by said switch to any selected channel of the communication lines.

33. The apparatus of claim 32, wherein said means for multi-channel communications includes a central processing unit.

34. The apparatus of claim 33, wherein said means for segmenting includes:

means for determining the bandwidth of each of the channels through which said plurality of communication connections have been established; and

means coupled with said bandwidth determining means for dividing each of said data packets into a first plurality of sub-packets the size of said sub-packets corresponding to the bandwidth of each of the channels determined by said bandwidth determining means.

35. The apparatus of claim 34, wherein a first one of said plurality of sub-packets has a first size, a second one of said plurality of said sub-packets has a second size, said first size being larger than said second size.