`Patel et al.
`
`[19]
`
`US005883894A
`Patent Number:
`Date of Patent:
`
`[11]
`[45]
`
`5,883,894
`Mar. 16, 1999
`
`[54]
`
`[75]
`
`SHARED AUTO-NEGOTIATION LOGIC FOR
`MULTIPLE PORT NETWORK DEVICES
`Inventors: Sandeep A. Patel, Cupertino; Claude
`G. Hayek, Mountain View, both of
`Calif.
`
`Assignee: 3Com Corporation, Santa Clara, Calif.
`
`Appl. No.: 774,480
`
`Filed:
`
`Dec. 30, 1996
`
`6
`Int. Cl. ................................................. .. H04L 12/413
`U-S- Cl- ------------------------ ~- 370/438; 370/ 447; 370/ 449;
`370/462
`Field of Search ................................... .. 370/465, 466,
`370/401, 437, 438, 439, 445, 447, 449,
`458, 461, 462
`
`[56]
`
`_
`References Clted
`
`Us‘ PATENT DOCUMENTS
`5/1994 Sambamurthy ....................... .. 370/296
`5,311,114
`7/1995 (jrayford ,,,,, ,,
`370/248
`5,432,775
`8/1996 Caspi et al.
`370/412
`5,546,385
`5,586,117 12/1996 Edem et al. ..
`370/466
`5,610,903
`3/1997 Crayford ..... ..
`370/213
`5,617,418
`4/1997 Shirani et al. ........................ .. 370/465
`
`OTHER PUBLICATIONS
`“Physical Layer Link Signaling for 10 Mb/s and 100 Mb/s
`algtggNegonanon on Twlsted Pan ’ IEEE’ pp' 235_280
`'
`Primary Examiner—Alpus H. Hsu
`Attorney, Agent, or Firm—Wilson Sonsini Goodrich &
`ROSaIi
`[57]
`
`ABSTRACT
`
`.
`.
`.
`.
`.
`A device interconnects across links, a plurality of terminals
`having respective modes of operation. The device includes
`a plurality of ports for connection to respective links, and
`logic Coupled to the plurality of ports to exercise an auto_
`negotiation protocol With terminals coupled to the respective
`links to resolve modes of operation. The logic includes a
`shared unit for executing the auto-negotiation protocol, and
`an arbiter unit for arbitrating among the plurality of ports for
`use of the shared unit. The arbiter connects ports in the
`plurality of ports to the shared unit in a round robin
`sequence. Memory stores a set of status signals for respec
`tive ports. The arbiter logic polls the memory to read the set
`of status signals in sequence, and in response enables use of
`the shared auto-negotiation unit by the ports. The modes of
`Operation resolved by the Shared auto-negotiation unit
`include LAN technology supported by terminals on the
`corresponding links, such as IEEE 802.3 Local Area Net
`Work technologies,
`
`12 Claims, 4 Drawing Sheets
`
`1 ——————————————————————————————— — ~ 1
`
`106-0
`
`:
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`1
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`i
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`1
`|
`:
`:
`|
`i
`l
`|
`|
`l
`
`E
`
`:
`
`A
`4—> PORT-0
`
`L 102.0
`
`H
`
`MANAGEMENT
`PROCESSOlil
`REPEATER
`<—>
`m
`
`CORE
`
`<—> PORT1
`
`1024
`
`<—> PORT 2
`SHARED AUTO-
`NEGOTIATE H
`1'1-
`LOGIC UNIT
`
`k 102-2
`
`'
`
`FRAME BUFFER <_> <_> PORT 3
`E
`
`k
`102-3
`a
`A103 9
`9
`
`4—> PORT n-1
`
`1
`I
`I
`1
`I
`:
`:
`I
`I
`i
`
`|
`
`|
`:
`E
`
`|
`l
`1
`I
`|
`I
`1
`:
`|
`1
`|
`|
`l
`l
`|
`l
`
`i
`I
`J!
`
`|
`l
`‘ ------------------------------- *-
`
`—
`
`\1o2-n-1
`
`(\107-0
`
`END STA.
`
`(10BASE-T)
`
`1064
`
`( 107'1
`END STA.
`(102335‘
`DUPLEX)
`10M (
`END STA.
`(10OBASE
`TX)
`
`107-2
`
`_
`
`106 3 (‘ 107-3
`END STA.
`(1ooBAsE
`TX FULL
`DUPLEX)
`
`106-n-1 107 1
`_n_
`(I
`(100BASE
`
`END STA.
`
`AMX and Dell, Inc.
`Exhibit 1034-00001
`
`
`
`U.S. Patent
`
`Mar. 16, 1999
`
`Sheet 1 of 4
`
`5,883,894
`
`MANAGEMENT
`PROCESSOR
`104
`
`REPEATER
`CORE
`
`101
`
`SHARED AUTO-
`NEGOTIATE
`
`LOGIC UNIT1 1
`
`FRAME BUFFER
`105
`
`END STA.
`
`(1 OBASE-T)
`
`(1 OBASE-T
`FULL
`
`DUPLEX)
`
`END STA.
`
`(100BASE-
`TX)
`
`END STA.
`
`(100BASE-
`TX FULL
`
`DUPLEX)
`
`END STA.
`
`(1OOBASE-
`T4)
`
`PORT n-1
`
`AMX and Dell, Inc.
`Exhibit 1034-00002
`
`
`
`U.S. Patent
`
`99916:1LaM
`
`Sheet 2 of 4
`
`5,883,894
`
`793.
`
`_,-c-moN
`
`._.z<_._n=>_Oomum.
`
`-O._.D<
`
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`
`29.82:".
`
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`
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`
`
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`
`mom
`
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`
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`
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`
`m._.<:.OOm_Zm_~._
`
`o_.N
`
`AMX and Dell, Inc.
`Exhibit 1034-00003
`
`
`
`U.S. Patent
`
`Mar. 16, 1999
`
`Sheet 3 014
`
`5,883,894
`
`RESET
`301 /-\ ,
`
`IDLE
`Set X = 0
`
`//—\ 300
`
`\soz
`V
`
`r
`
`Round-Robin_State
`Poll Status of Port X
`
`J 304
`AN Status Reg_X = 1
`306 /\
`+
`
`AN Status Reg_X = 0
`
`.
`OR
`M
`anagement__Renegot|ate
`
`Set X _ X+1
`
`mod (n-1)
`
`308 A Start 200ms
`Timer
`
`200ms Timer
`Expired
`
`A 315
`
`V
`AN_Port_X
`(set Port X
`309 /\ Selector, and
`assert
`Renegotiate)
`
`AN Done for Port X
`311 N
`
`k
`310
`
`/'\ 313
`
`Write_AN Status
`Reg_X
`
`F\ 312
`
`FIG. 3
`
`AMX and Dell, Inc.
`Exhibit 1034-00004
`
`
`
`U.S. Patent
`
`Mar. 16, 1999
`
`Sheet 4 of4
`
`5,883,894
`
`402
`w
`DONE_X ————> D
`
`SET
`
`Q
`
`401
`
`AN
`STATUS
`REG_X
`
`CLK J '>
`
`403
`
`CLR
`
`404
`
`405
`
`f‘ 406
`
`RESET
`
`408
`
`407
`
`FIG. 4
`
`AMX and Dell, Inc.
`Exhibit 1034-00005
`
`
`
`1
`SHARED AUTO-NEGOTIATION LOGIC FOR
`MULTIPLE PORT NETWORK DEVICES
`
`BACKGROUND OF THE INVENTION
`
`1. Field of the Invention
`Present invention relates to network intermediate devices
`for interconnecting terminals in a netWork across commu
`nication links; and more particularly to techniques used to
`resolve modes of operation for the links.
`2. Description of Related Art
`Communication netWorks consist of terminals that are
`interconnected by links to netWork intermediate devices
`such as repeaters, sWitches, bridges and the like. The inter
`mediate devices are used to interconnect the terminals to
`establish paths of communication among the terminals.
`As netWork technologies have developed, a Wide variety
`of techniques have evolved for operating links betWeen
`terminals and intermediate devices. For example, the ether
`net netWork standard according to the IEEE Standard 802.3,
`published by the Institute of Electrical and Electronic
`Engineers, supports a variety of local area netWork (LAN)
`technologies. These technologies include the 10 BASE-T
`standard Which speci?es a 10 megabit per second carrier
`sense multiple access With collision detection (CSMA/CD)
`LAN over tWo pairs of tWisted pair telephone Wire, the 10
`BASE-F standard Which speci?es a 10 megabit per second
`CSMA/CD LAN over ?ber optic cable; the 100 BASE-TX
`standard speci?es a 100 megabit per second CSMA/CD
`LAN over tWo pairs of category ?ve UTP or shielded tWisted
`pair Wire, and a number of other current and emerging
`technologies. Typically data terminals in a netWork are
`designed to support a speci?c LAN technology. HoWever,
`netWork intermediate devices Which are designed to inter
`connect a Wide variety of terminals, need a technique for
`resolving the particular technology used across a link
`coupled to a particular port of the device.
`To meet this need for resolving the LAN technology of a
`particular link the IEEE standards commissions have devel
`oped an auto-negotiation function Which speci?es physical
`layer signaling for 10 megabit per second and 100 megabit
`per second LAN technologies Which utiliZe tWisted pair
`Wiring. These technologies include 10 BASE-T, 10 BASE-T
`full duplex, 100 BASE-TX, 100 BASE-TX full duplex, and
`100 BASE-T4. The speci?ed auto-negotiation function is
`designed to support other technologies and neW LAN tech
`nologies as they evolve. The auto-negotiation function
`according to the standard alloWs a device to advertise
`enhanced modes of operation that it possesses to a device at
`the remote end of a link, and to detect corresponding
`enhanced modes of operation that the other device may be
`advertising. The auto-negotiation function automatically
`con?gures both devices to take maximum advantage of their
`abilities. The auto-negotiation function is performed at the
`physical layer relying on link integrity test pulse sequences
`(including normal link pulses NLPs and fast link pulses
`FLPs), so that no packet or upper layer protocol overhead is
`added to netWork devices for the purposes of this function.
`The auto-negotiation function is speci?ed in clause 28 of
`IEEE Standard 802.3u-1995, Institute of Electrical and
`Electronic Engineers, Inc., pages 235—280, and associated
`annexes. Clause 28 is incorporated by reference as if fully
`set forth herein.
`The auto-negotiation function is designed for implemen
`tation in the physical layer of each port on the netWork
`intermediate devices Which utiliZe the standard. See Clause
`
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`
`2
`28, supra, ?gure 28-2 “Location of Auto-Negotiation Func
`tion Within the ISO Reference Model” on page 237. Thus, a
`tWelve port repeater or other intermediate device, Will have
`tWelve instantiations of the auto-negotiation state machine.
`The auto-negotiation state machine is quite complicated,
`encompassing thousands of logic gates. Thus, the auto
`negotiation function signi?cantly increases the cost of net
`Work intermediate devices.
`Accordingly, it is desirable to provide an auto-negotiation
`function for netWork intermediate systems, With a more
`ef?cient architecture, so that expensive space on integrated
`circuits implementing the ports can be saved.
`
`SUMMARY OF THE INVENTION
`
`According to the present invention a device having an
`improved auto-negotiation function architecture is provided
`that interconnects across links, a plurality of terminals
`having respective modes of operation. The device includes
`a plurality of ports for connection to respective links, and
`logic coupled to the plurality of ports to exercise an auto
`negotiation protocol With terminals coupled to the respective
`links to resolve modes of operation. The logic includes a
`shared unit for executing the auto-negotiation protocol, and
`an arbiter unit for arbitrating among the plurality of ports for
`use of the shared unit. In one preferred embodiment, the
`arbiter includes logic Which connects ports in the plurality of
`ports to the shared unit in a round robin sequence.
`According to another aspect of the invention, the device
`includes memory storing a set of status signals for respective
`ports. The status signals indicate one of a resolved state and
`an unresolved state for the corresponding ports. The
`resolved state indicates that a mode of operation has been
`resolved for the link on the corresponding port. The unre
`solved state indicates that the mode of operation has not
`been resolved for the link on the corresponding port. The
`arbiter logic polls the memory to read the set of status
`signals in sequence, and in response enables use of the
`shared auto-negotiation unit by the ports.
`According to another aspect of the invention, the shared
`auto-negotiation unit generates a signal upon successful
`resolution of a mode of operation for a corresponding port.
`Logic is responsive to said signal to Write the status signals
`in the memory.
`According to a preferred aspect of the invention, the
`modes of operation resolved by the shared auto-negotiation
`unit include LAN technology supported by terminals on the
`corresponding links. More preferably, the LAN technologies
`comprise IEEE 802.3 Local Area NetWork technologies.
`According to yet another embodiment, the shared auto
`negotiation unit comprises an auto-negotiation function
`speci?ed according to IEEE Standard 802.3u, clause 28.
`The present invention can also be characteriZed as a
`method for automatically negotiating a mode of operation
`for a set of ports on a netWork device. The method comprises
`the steps of:
`monitoring status of ports in the set of ports according to
`a sequence to determine Whether a mode of operation
`is resolved or unresolved for selected ports in the
`sequence;
`for a selected port in the sequence, if the status indicates
`that a mode of operation is unresolved, then connecting
`the selected port to a shared auto-negotiation unit and
`executing an auto-negotiation protocol for the selected
`port to resolve a mode of operation; and
`changing the status of the selected port from unresolved
`to resolved, and returning to the step of monitoring.
`
`AMX and Dell, Inc.
`Exhibit 1034-00006
`
`
`
`3
`In accordance With the techniques discussed above, the
`method of the present invention includes storing status
`signals for the ports indicating Whether the mode of opera
`tion is resolved or unresolved, and the status of ports is
`monitored by polling the stored status signals.
`According to another aspect of the invention, the netWork
`intermediate device Which includes the shared auto
`negotiation unit according to the present invention, com
`prises a repeater. In alternative systems, the intermediate
`device comprises a sWitch or a bridge.
`According to one embodiment of the present invention, a
`master state machine is coupled With a shared auto
`negotiation state machine to be used by multiple ports in a
`netWork device. The master state machine operates at net
`Work device poWer up to connect the auto-negotiation state
`machine to one port at a time. The master state machine
`connects the shared auto-negotiation state machine to a neXt
`port When auto-negotiation is complete for the current port,
`or a timer has expired. During normal operation, after the
`poWer up sequence is complete, the master state machine
`checks each port for link status. If the link status is OK for
`the port being checked, then the master state machine moves
`to a neXt port. If the link status is not OK, then the master
`state machine connects the auto-negotiation state machine to
`the port, and Waits for auto-negotiation to successfully
`complete, or a timer to eXpire. This sequence is repeated by
`the master state machine in a round robin sequence. Once
`auto-negotiation is complete on a particular port, the link
`integrity state machine on the port brings the status of the
`link up. The link status check alloWs the auto-negotiation
`state machine to move to the neXt port, and reduces the
`overall time required to bring up link status on all ports of
`the netWork device.
`Accordingly, a shared auto-negotiation state machine is
`provided for netWork intermediate devices, based on a
`realiZation that in multiple port netWork devices, it is not
`necessary that all links be brought up simultaneously or in
`parallel. Furthermore, the invention is useful in any netWork
`device Which has multiple ports, such as repeaters, bridges
`and sWitches.
`In summary, the present invention alloWs netWork devices
`With multiple ports to be implemented With a shared auto
`negotiation state machine and a simple master state machine
`Which arbitrates use of the shared unit. This provides sub
`stantial cost advantages over the prior art by reducing the
`compleXity of logic required on each port.
`Other aspects and advantages of the present invention can
`be seen upon revieW of the ?gures, the detailed description
`and the claims Which folloW.
`
`BRIEF DESCRIPTION OF THE FIGURES
`
`FIG. 1 is a simpli?ed block diagram of a netWork includ
`ing an intermediate device With a shared auto-negotiation
`logic unit according to the present invention.
`FIG. 2 is a more detailed block diagram of a multiport,
`shared auto-negotiation device according to the present
`invention.
`FIG. 3 is a state diagram illustrating operation of the
`master state machine of FIG. 2.
`FIG. 4 is a simpli?ed diagram of an auto-negotiation
`status register for use in the system of FIG. 2.
`
`DETAILED DESCRIPTION
`A detailed description of preferred embodiments of the
`present invention is provided With respect to FIGS. 1
`through 4, in Which FIG. 1 illustrates a netWork intermediate
`
`65
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`5,883,894
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`device 100 including a shared auto-negotiation function
`according to the present invention. In FIG. 1, the netWork
`intermediate device 100 comprises a repeater, and includes
`a repeater core state machine 101 and shared autonegotiate
`unit 110 according to the present invention. In alternative
`systems, the netWork intermediate device 100 consists of a
`sWitch or a bridge, or other technology used for intercon
`necting netWork terminals.
`The device 100 includes a set of ports, including port (0)
`102-0 through port (n-1) 102-n-1. The set of ports 102-0
`through 102-n-1 is coupled to the repeater core 101 and
`shared autonegotiate unit 110 across bus 103. In addition, a
`repeater management processor 104 and optionally a frame
`buffer 105 are included, and coupled to the bus 103.
`In alternative architectures, the set of ports 102-0 through
`102-n-1 is coupled directly to the repeater core in a star
`con?guration. Also, other interconnection technologies can
`be used depending on the particular environment.
`Ports in the set of ports 102-0 through 102-n-1 are
`coupled to respective links 106-0 through 106-n-1. A plu
`rality of end stations 107-0 through 107-n-1 are coupled to
`the links 106-0 through 106-n-1 respectively. Each of the
`end stations (or other netWork terminals) has a respective
`mode of operation according to the LAN technology sup
`ported by the terminal. In the eXample of FIG. 1, end station
`107-0 supports 10 BASE-T technology. End station 107-1
`supports 10 BASE-T full dupleX technology. End station
`107-2 supports 100 BASE-TX technology. End station
`107-3 supports 100 BASE-TX full dupleX technology. End
`station 107-n-1 supports 100 BASE-T4 technology.
`According to the present invention, rather than imple
`menting an auto-negotiation state machine in each of the
`ports 102-0 through 102-n-1, a shared auto-negotiation unit
`110 is coupled to the set of ports. The shared autonegotiate
`logic performs the IEEE 802.3u Clause 28 auto-negotiation
`function in a preferred system, to automatically resolve a
`mode of operation for each of the ports for the tWisted pair
`Wiring based technologies speci?ed according to 802.3
`CSMA/CD netWorks.
`Implementation of the shared auto-negotiation unit 110 is
`illustrated in FIG. 2. In FIG. 2, the architecture is illustrated
`for an IEEE compliant 802.3 auto-negotiation function.
`Thus, a shared auto-negotiation function unit 200 is pro
`vided. The set of ports 107-0 through 107-n-1 is shoWn.
`Coupled With each port is a link state machine 201-0 through
`201-n-1. The link pulses received and transmitted through
`the ports in the set of ports 107-0 through 107-n-1 are
`coupled to a selector 202 across lines 203-0 through 203
`n-1. The selector comprises an n-to-1 port multiplexer
`Which connects the received link pulses from a selected port
`across line 204 to the shared auto-negotiation function 200,
`and supplies the link pulses Which are transmitted by the
`auto-negotiation function 200 across line 205 to the selected
`port. A shared auto-negotiation master state machine 206
`generates a PORT X SELECTOR signal on line 207, Which
`controls the selector 202. Link status signals, including the
`LINKiOK signal from the selected port are supplied on line
`208 to the master state machine 206. Also, When the auto
`negotiation function 200 completes resolving the mode of
`operation for a select port, a DONE signal is supplied to the
`master state machine 206 on line 209. Other inputs to the
`master state machine 206 include a management renegotiate
`signal on line 210, and a RESET signal on line 211. The
`shared autonegotiate master state machine 206 selects a
`current port, and issues a RENEGOTIATE signal on line 212
`to the shared unit 200. After the RENEGOTIATE signal is
`
`AMX and Dell, Inc.
`Exhibit 1034-00007
`
`
`
`10
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`5
`issued, and the master state machine 206 Waits to receive a
`DONE signal on line 209, or until expiration of the timer as
`discussed below.
`The status signals for the individual ports are stored in the
`autonegotiate status registers 213 Which are coupled With the
`master state machine 206 in this example. When the mode
`of operation for a particular port is successfully resolved,
`then the master state machine Writes a resolved status to the
`corresponding status register. When, the status register
`stores a status signal indicating an unresolved state, the
`master state machine 206 periodically retries to resolve a
`mode of operation.
`FIG. 3 illustrates in more detail, the operation of the
`master state machine 206 in FIG. 2. The master state
`machine includes an idle state 300, in Which a port selector
`parameter X is set to 0. The idle state 300 is entered by
`assertion of the RESET signal as indicated by line 301. From
`the idle state, the state machine transitions on line 302 to a
`round robin state 303. In state 303, the status of port X is
`polled. If the status is resolved, indicated by a logic 1 stored
`in the corresponding status register, then the state machine
`transitions on line 304 to state 305, Where the parameter X
`is incremented, modulo n-1. After the parameter X is
`incremented, the algorithm loops back to the round robin
`state 303 to test the next port so that the ports are polled in
`a round robin fashion. Other polling sequences may also be
`used, including priority based sequences or user speci?ed
`sequences as suit a particular environment.
`If in state 303, the corresponding status register indicates
`that the port is in an unresolved state, corresponding to a
`logic 0 in the corresponding register, or if a management
`renegotiate signal is received for port X, then the algorithm
`transitions on line 307 to state 308 Where a 200 millisecond
`timer is started. Of course the length of the timer is deter
`mined according to a number of factors such as auto
`negotiation protocol used, and can be optimiZed to meet a
`particular situation.
`Next, the algorithm transitions from state 308 to the
`autonegotiate state 309, Where the port X selector signal on
`line 207 is set to select port X, and the RENEGOTIATE
`signal is asserted on line 212. At state 309, the algorithm
`transitions on line 310 back to the increment state 305, if the
`timer expires before auto-negotiation is completed.
`If the DONE signal is received from line 209 before the
`timer expires, then the master state machine transitions on
`line 311 to state 312, Where the status register for the
`corresponding port is Written With a resolved status signal,
`corresponding to a logic 1 in this example. After Writing
`status, then the algorithm transitions on line 313 back to the
`state 305 to increment the parameter X.
`Thus, initially, When the master state machine transitions
`from the idle to the round robin states, the port selector is set
`to port 0. The selector gets incremented one by one until it
`reaches n-1, for a total of n ports. X can also be set by the
`management entity, if the latter needs to renegotiate on a
`certain port. Atimer, in this example, 200 milliseconds starts
`for port X, When the master state machine enters the state
`309 to autonegotiate for port X. The timer gets reset upon
`entering the round robin state 303. The timer serves as a
`“move to next port” indicator, if the mode of operation of the
`port cannot be successfully renegotiated.
`FIG. 4 illustrates the auto-negotiation status register for
`an individual port, used as a memory 213 in system of FIG.
`2. Thus, a D-type register 400 in this example, stores an
`auto-negotiation status signal AN STATUS REGiX, and
`outputs the status signal on line 401. The D input for the
`
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`register 401 is supplied on line 402, from the DONE line 209
`of FIG. 2. The clock signal 403 clocks the register 400 With
`appropriate timing under control of the state machine. The
`register 400 is reset by a signal on line 404. The signal on
`line 404 is supplied at the output of OR gate 405. The inputs
`to OR gate 405 include the RESET signal 406 Which
`corresponds to the RESET signal 301 in FIG. 3 (also the
`RESET signal 211 in FIG. 2). The other input to the OR gate
`405 comprises the output of inverter 407. The input to the
`inverter 407 is the LINKiOKiX signal on line 408. This
`signal corresponds to the LINKiOK signal on the line 208
`of FIG. 2, for a selected port X. Thus, the register 400 is
`cleared at poWer on reset, or When the LINKiOK signal for
`port X is at logic 0, indicating that the link is doWn. The
`register is Written by the master state machine When the port
`has been successfully autonegotiated as indicated by the
`DONE signal on line 402.
`In conclusion, the present invention provides for the use
`of shared auto-negotiation state machine on a netWork
`intermediate device. A master state machine arbitrates
`among the ports on the device for use of the shared auto
`negotiation state machine. The invention is applicable to any
`netWork device Which has multiple ports, such as repeaters,
`bridges and sWitches. According to the present invention,
`substantial savings in integrated circuit complexity are
`made, Without compromising functionality of the device,
`because it is unnecessary that auto-negotiation state
`machines operate in parallel on a multiple ports in a single
`device. Rather, a shared auto-negotiation state machine can
`effectively serve many ports in a single netWork intermedi
`ate device.
`The foregoing description of a preferred embodiment of
`the invention has been presented for purposes of illustration
`and description. It is not intended to be exhaustive or to limit
`the invention to the precise forms disclosed. Obviously,
`many modi?cations and variations Will be apparent to prac
`titioners skilled in this art. It is intended that the scope of the
`invention be de?ned by the folloWing claims and their
`equivalents.
`What is claimed is:
`1. A device Which interconnects across links a plurality of
`terminals having respective modes of operation, comprising:
`a plurality of ports for connection to respective links;
`memory storing a set of status signals, status signals in the
`set indicating states of corresponding ports in the
`plurality of ports, Wherein status signals in the set
`indicate one of a resolved state and an unresolved state,
`the resolved state indicating that a mode of operation
`has been resolved for the link on the corresponding
`port, and the unresolved state indicating that a mode of
`operation has been not resolved for the link on the
`corresponding port;
`a shared unit coupled to the plurality of ports to exercise
`an auto-negotiation protocol With terminals coupled the
`respective links to resolve modes of operation for the
`respective links, Wherein the modes of operation
`resolved by the shared unit include local area netWork
`LAN technologies supported by terminals on the cor
`responding links; and
`arbiter logic Which polls the memory to read the set of
`status signals in a sequence, and in response to status
`signals in the set, enables use of the shared unit by the
`corresponding ports.
`2. The device of claim 1, Wherein the arbiter logic
`comprises logic to poll the memory in a round robin
`sequence.
`
`AMX and Dell, Inc.
`Exhibit 1034-00008
`
`
`
`5,883,894
`
`7
`3. The device of claim 1, comprising:
`a selector responsive to the arbiter unit, having a plurality
`of inputs coupled to corresponding ports in the plurality
`of ports, and having an output coupled to the shared
`unit.
`4. The device of claim 1, Wherein the shared unit gener
`ates a signal upon successful resolution of a mode of
`operation for a corresponding port, and including logic
`responsive to said signal to Write status signals in the set to
`the memory.
`5. The device of claim 1, Wherein the modes of operation
`resolved by the shared unit include IEEE 802.3 local area
`netWork LAN technologies supported by terminals on the
`corresponding links.
`6. The device of claim 5, Wherein the auto-negotiation
`protocol executed by the shared unit comprises an auto
`negotiation function speci?ed according to IEEE Standard
`802.3.
`7. A device Which interconnects across links a plurality of
`terminals having respective modes of operation, comprising:
`a plurality of ports for connection to respective links;
`logic coupled to the plurality of ports to exercise a
`protocol With terminals coupled the respective links to
`resolve modes of operation for the respective links, the
`logic including a shared unit for executing the protocol;
`and
`an arbiter unit for arbitrating among the plurality of ports
`for use of the shared unit, the arbiter unit comprising:
`memory storing a set of status signals, status signals in
`the set indicating states of corresponding ports in the
`plurality of ports; and
`logic Which polls the memory to read the set of status
`signals in a sequence, and in response to status
`signals in the set, enables use of the shared unit by
`the corresponding ports.
`8. The device of claim 7, Wherein status signals in the set
`indicate one of a resolved state and an unresolved state, the
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`15
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`25
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`resolved state indicating that a mode of operation has been
`resolved for the link on the corresponding port, and the
`unresolved state indicating that a mode of operation has
`been not resolved for the link on the corresponding port.
`9. The device of claim 8, Wherein the shared unit gener
`ates a signal upon successful resolution of a mode of
`operation for a corresponding port, and including logic
`responsive to said signal to Write status signals in the set to
`the memory.
`10. A method for automatically negotiating a mode of
`operation for a set of ports on a netWork device, comprising:
`monitoring status of ports in the set of ports according to
`a sequence to determine Whether a mode of operation
`is resolved or unresolved for selected ports in the
`sequence;
`for a selected port in the sequence, if the status indicates
`that a mode of operation is unresolved, then connecting
`the selected port to a shared auto-negotiation unit and
`executing an auto-negotiation protocol for the selected
`port to resolve a mode of operation for the selected
`port;
`storing status signals in memory for the set of ports
`indicating for ports in the set Whether a mode of
`operation is resolved or unresolved; and
`changing the status of the selected port from unresolved
`to resolved, and returning to the step of monitoring,
`said monitoring step includes polling the stored status
`signals.
`11. The method of claim 10, Wherein the step of moni
`toring includes polling the stored status signals according to
`a round robin sequence.
`12. The method of claim 10, including generating a signal
`upon successful resolution of a mode of operation for the
`selected port, and Writing in response to said signal the status
`signals in the set to memory.
`
`*
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`*
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`*
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`*
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`*
`
`AMX and Dell, Inc.
`Exhibit 1034-00009