High speed communication bus

• US 5,781,745 A
• Filed: 05/20/1996
• Issued: 07/14/1998
• Est. Priority Date: 05/20/1996
• Status: Expired due to Term

• Current Assignee: Hewlett Packard Enterprise Development LP (Hewlett-Packard Enterprise Company)
• Original Assignee: 3Com Corporation (HP Inc.)
• Inventors: Lorenz, Gary, Robins, Cary, Driscoll, Peter, Itkowsky, Frank, Bovopoulos, Andreas, Ramelson, Brian
• Primary Examiner(s): AUVE, GLENN ALLEN
• Application Number:
  US08/651,804
• Time in Patent Office: 785 Days
• Field of Search: 395/309, 395/281, 395/299, 395/301, 395/305, 395/291, 395/293, 395/287, 395/200.02, 395/200.05, 395/200.06, 395/200.2, 395/200.21, 395/200.8 , 395/200.33, 395/200.55, 395/200.59
• US Class Current: 710/113
• CPC Class Codes: G06F 13/387 for adaptation of different data processing systems to different peripheral devices, e.g. protocol converters for incompatible systems, open system

Abstract

A computer network system containing a concentrator with a backplane that has a plurality of lines. The backplane contains data lines and control lines for managing and organizing the transfer of data between modules in the concentrator. The system contains intelligent devices that allow the selection of transmitting modules to occur at the same time as actual data transfer is going on between other modules. This is preferably done in a round robin arbitration process where, while data is being transferred by a first module, a bus arbitration device is placing addresses of modules which sequentially follow the transmitting module onto the control lines. Modules will see their address on the control lines, and if they have a packet to transmit, they then reserve the right to transmit after the presently transmitting module is finished. In this way the selection of the next module to transmit is performed in parallel, and does not slow down, the transfer of data between modules. The control lines are also able to indicate when a receiving module has been unable to copy a packet. The transmitting module can then resend the packet for either a maximum number of retries, or until the receiving module is able to copy the packet.

Claims

1. A computer network concentrator system, comprising:

a backplane with a DATA line, a BUSY line parallel with said DATA line and a SLOTSEL line parallel with said DATA line;

a plurality of modules connected to said DATA, BUSY, and SLOTSEL lines, each of said plurality of modules having a unique slot ID, said SLOTSEL line being capable of transmitting any one of said unique slot ID'"'"'s, one of said plurality of modules being an active arbitration module and having a Bus Arbiter means for selecting which of said plurality of modules will transmit data onto said DATA line, said Bus Arbiter means transmitting said unique slot ID of one of said modules onto said SLOTSEL line;

each of said plurality of modules including a Transmitter means for monitoring said SLOTSEL line for a respective unique slot ID on said SLOTSEL line, monitoring said BUSY line for a BUSY signal, said Transmitter means transmitting a BUSY signal onto said BUSY line and subsequently transmitting a packet onto said DATA line upon said Transmitter means detecting that said BUSY line does not have a BUSY signal, detecting that said SLOTSEL line has said unique slot ID and a detecting that a respective module associated with said Transmitter means has said packet to transmit onto said DATA line.

2. A system in accordance with claim 1, wherein:

said Bus Arbiter means periodically transmits each SLOT ID of said plurality of modules onto said SLOTSEL line.

3. A system in accordance with claim 2, wherein said backplane further comprises a SLOTACK line parallel with said DATA line;

said Transmitter means transmits a SLOTACK signal onto said SLOTACK line if said SLOTSEL line has said respective SLOT ID, said BUSY line has a BUSY signal and said respective module has a packet to transmit onto said DATA line, said Transmitter means removes said SLOTACK signal from said SLOTACK line when said BUSY signal is removed from said BUSY line, said Transmitter means then transmits said BUSY signal onto said BUSY line and transmits said packet onto said data line;

said Bus Arbiter means halting periodic transmitting of said each SLOT ID onto said SLOTSEL line when said SLOTACK signal is on said SLOTACK line.

4. A system in accordance with claim 3, wherein:

said Transmitter means removes said BUSY signal from said BUSY line after said packet has been transmitted onto said DATA line;

said Bus Arbiter means resumes periodically transmitting said each SLOT ID when said SLOTACK signal is removed.

5. A system in accordance with claim 3, wherein:

a CLOCK line is parallel with said DATA line, said clock line maintains a CLOCK signal with a plurality of clock cycles;

said Bus Arbiter means transmits a SLOT ID onto said SLOTSEL line for three of said clock cycles, said Bus Arbiter means then transmits another SLOT ID onto said SLOTSEL line;

when said Transmitter means transmits said SLOTACK signal onto said SLOTACK line, said Transmitter transmits on a second clock cycle after said respective SLOT ID is present on said SLOTSEL line;

said Bus Arbiter means receives said SLOTACK signal from said SLOTACK line on a third clock cycle and does not transmit any further SLOT ID until said SLOTACK signal is removed from said SLOTACK line.

6. A system in accordance with claim 5, wherein:

said Transmitter means removes said BUSY signal from said BUSY line during a last three clock cycles of transmitting of said packet onto said DATA line.

7. A system in accordance with claim 6, wherein:

said Bus Arbiter means and said Transmitter means operate in parallel and synchronous with said transmitting of said packet onto said DATA line.

8. A system in accordance with claim 5, further comprising:

a STAT line parallel with said DATA line, said Transmitter means transmitting a HEADER CYCLE signal onto said STAT line when said Transmitter means transmits a header of said packet onto said DATA line, said Transmitter means transmitting a DATA CYCLE signal onto said STAT line when said Transmitter means transmits a data portion of said packet onto said DATA line, said Transmitter means transmitting an END OF CYCLE signal onto said STAT line when said Transmitter means transmits a last three clock cycles of said data portion onto said DATA line, said STAT line defaults to a BUS IDLE signal when no signals are transmitted onto said STAT LINE.

9. A system in accordance with claim 5, wherein:

an ARBACT line is parallel with said DATA line;

an ESYNCH line is parallel with said DATA line;

said plurality of modules are connected to said ARBACT and ESYNCH lines;

said each of said plurality of modules has Master Elect Arbiter means for electing one of said plurality of modules to be said active arbitration module and disabling all Bus Arbiter means on modules not elected as said active arbitration module, said Master Elect Arbiter means operating in parallel with said DATA line and synchronous with said CLOCK signal.

10. A system in accordance with claim 9, wherein:

a PR (Port Ready) line is parallel with said DATA line;

a PNR (Port Not Ready) line is parallel with said DATA line;

said plurality of modules connect to said PR and PNR lines, each of said Transmitter means transmitting a PR signal onto said PR line if said respective module is properly receiving a packet from said DATA line, each of said Transmitter means transmitting a PNR signal onto said PNR line if said respective module can not properly copy said packet from said DATA line.

11. A system in accordance with claim 3, wherein:

one of said Transmitter means can immediately retransmit said SLOTACK signal onto said SLOTACK line after said one Transmitter means has removed said SLOTACK signal from said SLOTACK line during transmitting of said packet onto said DATA line if no other Transmitter means of other said modules transmit said SLOTACK signal and said Bus Arbiter means again selects said respective SLOT ID of said one Transmitter means.

12. A system in accordance with claim 1, wherein:

said DATA line includes a plurality of transmission paths transmitting data from said packet in parallel;

said SLOTSEL line includes a plurality of transmission paths transmitting said each SLOT ID in parallel.

13. A system in accordance with claim 1, wherein:

said Bus Arbiter means gathers said SLOT ID of each of said plurality of modules and only periodically transmits said SLOT ID of modules connected to said DATA, BUSY and SLOTSEL lines.

14. A management system for a backplane of a computer network, the system comprising:

an ARBACT line;

an ESYNCH line parallel with said ARBACT line;

a SLOTSEL line parallel with said ARBACT line, said SLOTSEL line having a dominant state and a recessive state, said SLOTSEL line maintaining said dominant state when both said dominant and recessive states are transmitted onto said SLOTSEL line;

a plurality of modules connected to said ARBACT, SLOTSEL and ESYNCH lines, each of said plurality of modules having a SLOT ID, each SLOT ID including a plurality of dominant and recessive states, said SLOTSEL line being capable of transmitting said SLOT ID, each of said plurality of modules having Bus Arbiter means for selecting which of said plurality of modules will transmit data onto the backplane, said each of said plurality of modules also having Master Elect Arbiter means for electing one of said plurality of modules to be an active arbitration module and disabling all Bus Arbiter means on modules not elected as said arbitration module, said Master Elect Arbiter means of said active arbitration module transmitting an ARBACT signal onto said ARBACT line, each of said Master Elect Arbiter means transmitting an ESYNCH signal onto said ESYNCH line if said ARBACT signal is missing from said ARBACT line, said each Master Elect Arbiter means removing said ESYNCH signal from said ESYNCH line after a predetermine time period, said each Master Elect Arbiter means transmitting a respective arbiter version field and a respective SLOT ID onto said SLOTSEL line after all ESYNCH signals are removed from said ESYNCH line, said each Master Elect Arbiter means monitoring a state of said SLOTSEL line, if said SLOTSEL line has a state other than a state transmitted by said Master Elect Arbiter means, said Master Elect Arbiter means stops transmitting onto said SLOTSEL line and disables a respective said Bus Arbiter means, a Master Elect Arbiter means still transmitting after all other Master Elect Arbiter means have finished said transmitting of said respective SLOT ID'"'"'s onto said SLOTSEL line is a remaining Master Elect Arbiter means and transmits said ARBACT signal onto said ARBACT line.

15. A system in accordance with claim 14, wherein:

said each module includes an Arbiter VERSION FIELD, each Arbiter VERSION FIELD including a plurality of dominant and recessive states, said SLOTSEL line being capable of transmitting said VERSION FIELD and said respective SLOT ID, said each Master Elect Arbiter means transmitting said VERSION FIELD and said respective SLOT ID onto said SLOTSEL line after said all ESYNCH signals are removed from said ESYNCH line.

16. A system in accordance with claim 15, wherein:

said VERSION FIELD is programmable for each of said plurality of modules.

17. A system in accordance with claim 14, wherein:

a CLOCK line is parallel with said ARBACT line, said clock line maintains a CLOCK signal with a plurality of clock cycles;

said each Master Elect Arbiter means transmits said SLOT ID onto said SLOTSEL line one bit at a time starting with a most significant bit, said each Master Elect Arbiter means asserts a first bit of said SLOT ID on a first clock cycle after said all ESYNCH signals are removed from said ESYNCH line, said each Master Elect Arbiter means transmits said first bit of said SLOT ID onto said SLOTSEL line on a second clock cycle after said all ESYNCH signals are removed from said ESYNCH line, said each Master Elect Arbiter means reads said state of said SLOTSEL line on a third clock cycle after said all ESYNCH signals are removed from said ESYNCH line, said each Master Elect Arbiter means decides whether or not to stop transmitting onto said SLOTSEL line and disable said respective Bus Arbiter means on a fifth clock cycle after said all ESYNCH signals are removed from said ESYNCH line.

18. A system in accordance with claim 17, wherein:

said each Master Elect Arbiter means sequentially transmits all remaining bits of said SLOT ID in a manner similar to the transmitting of said first bit.

19. A system in accordance with claim 14, wherein:

said Master Elect arbiter means of said active arbitration module removes said ARBACT signal from said ARBACT line when said ESYNCH signal is present on said ESYNCH line;

each of said plurality of modules being capable of transmitting said ESYNCH signal onto said ESYNCH line to re-elect said active arbiter module.

20. A management system for a backplane of a computer network, the system comprising:

a DATA line;

a PR (Port Ready) line parallel with said DATA line;

a PNR (Port Not Ready) line parallel with said DATA line;

a plurality of modules connected to said DATA, PR and PNR lines, each of said plurality of modules including Transmitter means for transmitting and receiving a packet onto and from said DATA line, each of said Transmitter means transmitting a PR signal onto said PR line if said Transmitter means is properly receiving said packet from said DATA line, each of said Transmitter means transmitting a PNR signal onto said PNR line if said Transmitter means can not properly copy said packet from said DATA line.

21. A system in accordance with claim 20, wherein:

a module transmitting a packet onto said DATA line is a bus master, if a Transmitter means of said bus master detects said PR and PNR signal said packet is fully transmitted onto said DATA line and said packet is held by said bus master for retransmission when said module is again bus master;

if a Transmitter means of said bus master detects only said PNR signal, said packet is aborted and said packet is held by said bus master for retransmission when said module is again bus master,

if a Transmitter means of said bus master detects neither said PR and PNR signal said packet is aborted and discarded;

if a Transmitter means detects said PR and not PNR said packet is fully transmitted onto said data line.

22. A system in accordance with claim 21, wherein:

a STAT line is parallel with said DATA line, said Transmitter means transmitting a CYCLE ABORT signal onto said STAT line when said packet is aborted;

said Transmitter means transmitting a RETRY signal onto said STAT line when said Transmitter means retransmits said packet onto said DATA line.

23. A system in accordance with claim 22, wherein:

said each Transmitter means includes register means for determining if a packet transmitted onto said DATA line with said RETRY signal on said STAT line has already been properly received.

24. A system in accordance with claim 23, wherein:

said register means includes a bit for each of said plurality of modules, said register means of a receiving module setting one of said bits to a fail value when said receiving module is unable to receive said packet from a corresponding module;

said transmitting means only copying a packet with a corresponding RETRY signal if a corresponding bit in said register means has said fail value, if said transmitter means successfully copies said packet with said retry signal, said register means sets said corresponding bit to a pass value.

25. A system in accordance with claim 21, wherein:

said Transmitter means is programmable with regard to a number of times said packet is retransmitted.

26. A computer network concentrator system, comprising:

a backplane with a DATA line and an arbitration line in parallel and operating simultaneously with said DATA line;

a plurality of modules connected to said DATA line and said arbitration line, each of said plurality of modules having a unique slot ID, said arbitration line being capable of transmitting any one of said unique slot ID'"'"'s onto said arbitration line, one of said plurality of modules being an active arbitration module and having a Bus Arbiter means for selecting which of said plurality of modules will transmit data onto said DATA line, said Bus Arbiter means transmitting said unique slot ID of one of said modules onto said arbitration line;

each of said plurality of modules including a Transmitter means for monitoring said arbitration line for a respective said unique slot ID on said arbitration line, said Transmitter means transmitting onto said DATA line upon said Transmitter means detecting that said Arbitration line has said unique slot ID.

27. A computer network concentrator system in accordance with claim 26, wherein:

said Transmitter means in addition only transmits onto said DATA line when said Transmitter means detects that a respective module associated with said Transmitter means has a packet to transmit onto said DATA line.

28. A computer network concentrator system in accordance with claim 26, wherein:

said Transmitter means of all of said plurality of modules listen to said arbitration line in a bus type arrangement.