(12) United States Patent
`Westby
`
`I 1111111111111111 11111 lllll lllll 111111111111111 lllll 111111111111111 11111111
`US006279057Bl
`US 6,279,057 Bl
`Aug. 21, 2001
`
`(10) Patent No.:
`(45) Date of Patent:
`
`(54) COMMUNICATIONS SYSTEM HAVING
`DEDICATED FRAME BUFFERS LOCATED
`IN A CHANNEL NODE CONNECTED TO
`TWO PORTS OF THE CHANNEL NODE FOR
`RECEIVING FRAMES
`
`(75)
`
`Inventor: Judy Lynn Westby, Bloomington, MN
`(US)
`
`(73) Assignee: Seagate Technology, Inc., Scotts
`Valley, CA (US)
`
`( *) Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by O days.
`
`(21) Appl. No.: 09/193,681
`
`(22) Filed:
`
`Nov. 17, 1998
`
`Related U.S. Application Data
`(60) Provisional application No. 60/065,920, filed on Nov. 17,
`1997, provisional application No. 60/065,926, filed on Nov.
`17, 1997, provisional application No. 60/065,919, filed on
`Nov. 17, 1997, and provisional application No. 60/067,211,
`filed on Dec. 1, 1997.
`Int. Cl.7 ...................................................... G06F 13/14
`(51)
`(52) U.S. Cl. ................................................... 710/52; 710/7
`(58) Field of Search ............................. 710/7, 52, 36-38;
`709/236, 251; 370/400
`
`(56)
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`4,486,739
`4,819,229
`
`12/1984 Franaszek et al. ................... 340/347
`4/1989 Pritty et al. . ... ... ... ... .... ... ... ... .. 370/89
`
`(List continued on next page.)
`
`OIBER PUBLICATIONS
`
`"Fibre Channel, Arbitrated Loop (FC-AL), REV 4.5",
`American National Standard for Information Technology
`draft proposed, ANSI X3.272-199 X, (Jun. 1, 1995).
`
`"Fibre Channel, Arbitrated Loop (FC-AL-2), REV 6.3",
`American National Standard for Information Technology
`draft proposed, ANSI X3.xxx-199x, (May 29, 1998).
`"Fibre Channel, Physical and Signaling Interface (FC-PH),
`REV 4.3", American National Standard for Informations
`Systems working draft, ANSI X3.230-199x, (Jun. 1, 1994).
`"Information Systems----dpANS Fibre Channel Protocol for
`SCSI", American National Standard----draft proposed,
`X3.269-199x revision 12, (Dec. 4, 1995).
`Georgiou, C. J., et al., "Scalable Protocol Engine for High(cid:173)
`Bandwidth Communications", IEEE, pp. 1121-1126,
`(1997).
`
`Primary Examiner-Thomas Lee
`Assistant Examiner-Thuan Du
`(74) Attorney, Agent, or Firm----Schwegman, Lundberg,
`Woessner & Kluth P.A.
`
`(57)
`
`ABSTRACT
`
`Dedicated receive buffers for receiving non-data frames are
`provided for each port of a two-port node in a fibre-channel
`arbitrated-loop serial communications channel design. The
`improved communications channel system and method
`includes a channel node having dual ports each supporting
`a communications channel, both ports interfaced from a
`single interface chip, and a dedicated on-chip frame buffer
`located on the chip for receiving frames. The dedicated
`on-chip frame buffer includes two inbound non-data buffers,
`one coupled to each of two ports, wherein inbound non-data
`frames from each port are received into the respective
`inbound non-data buffer. The system further includes an
`off-chip buffer, wherein received non-data frames are
`received into one of the non-data-frame buffers and trans(cid:173)
`ferred from the non-data-frame buffer to the off-chip buffer.
`A data-frame buffer is operatively coupled to both ports to
`receive data frames from the ports, and move the data frames
`to the off-chip buffer. In addition, a method for receiving
`frames using the dedicated buffer is described.
`
`22 Claims, 15 Drawing Sheets
`
`PORT A
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`
`Petitioners Microsoft Corporation and HP Inc. - Ex. 1008, p. 1
`
`

`

`US 6,279,057 Bl
`Page 2
`
`U.S. PATENT DOCUMENTS
`.......................
`395/725
`12/1992 Thayer et al.
`11/1993 Rouse ..................................... 370/14
`....................
`7/1996 DeFoster et al.
`359/161
`1/1997 Malladi ................................ 395/286
`4/1997 Anderson ............................ 371/10.2
`4/1997 Gallagher et al. ................... 370/394
`4/1997 Jardine .............................. 395/200.7
`6/1997 Malladi ........................... 395/200.21
`9/1997 Westby ................................... 341/59
`12/1997 Thapar et al. ....................... 395/822
`..............................
`5/1998 Aytac
`395/200.41
`...................
`6/1998 Lundberg et al.
`395/870
`6/1998 DeKoning et al. .................. 711/113
`6/1998 Schmahl et al. ..................... 395/287
`6/1998 Crouse et al. ....................... 395/601
`6/1998 Sandorfi .......................... 395/200.63
`6/1998 Judd et al. ........................... 395/857
`7/1998 DeKoning et al. .................. 711/122
`
`5,168,568
`5,260,933
`5,535,035
`5,598,541
`5,617,425
`5,619,497
`5,619,647
`5,638,518
`5,663,724
`5,694,615
`5,758,081
`5,761,534
`5,761,705
`5,764,931
`5,764,972
`5,768,530
`5,768,623
`5,778,426
`
`5,781,801
`5,787,242
`5,787,450
`5,790,773
`5,790,792
`5,802,080
`5,805,788
`5,805,920
`5,807,261
`5,809,328
`5,812,564
`5,812,754
`5,815,662
`5,819,054
`5,819,111
`5,822,143
`5,822,782
`6,012,128
`
`7/1998 Flanagan et al. .................... 395/876
`7/1998 DeKoning et al. ............. 395/182.03
`.....................
`7/1998 Diedrich et al.
`707/513
`8/1998 DeKoning et al. ............. 395/182.04
`8/1998 Dudgeon et al. ............... 395/200.42
`9/1998 Westby ................................... 371/53
`9/1998 Johnson .......................... 395/182.04
`9/1998 Sprenkle et al. . .................... 395/821
`. ....................
`9/1998 Benaron et al.
`600/473
`......................
`9/1998 Nogales et al.
`395/825
`.......................
`9/1998 Bonke et al.
`371/40.1
`........................
`9/1998 Lui et al.
`395/182.04
`Ong ................................. 395/200.47
`9/1998
`10/1998 Ninomiya et al. ................... 395/308
`10/1998 Davies et al. ........................ 395/849
`10/1998 Cloke et al. ........................... 360/65
`10/1998 Humlicek et al. . .................. 711/170
`1/2000 Birns et al. . ......................... 711/163
`
`Petitioners Microsoft Corporation and HP Inc. - Ex. 1008, p. 2
`
`

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`
`Petitioners Microsoft Corporation and HP Inc. - Ex. 1008, p. 3
`
`

`

`U.S. Patent
`
`Aug. 21, 2001
`
`Sheet 2 of 15
`
`US 6,279,057 Bl
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`Petitioners Microsoft Corporation and HP Inc. - Ex. 1008, p. 4
`
`

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`Petitioners Microsoft Corporation and HP Inc. - Ex. 1008, p. 5
`
`

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`
`Petitioners Microsoft Corporation and HP Inc. - Ex. 1008, p. 6
`
`

`

`U.S. Patent
`
`Aug. 21, 2001
`
`Sheet 5 of 15
`
`US 6,279,057 Bl
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`Petitioners Microsoft Corporation and HP Inc. - Ex. 1008, p. 7
`
`

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`
`Petitioners Microsoft Corporation and HP Inc. - Ex. 1008, p. 8
`
`

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`
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`
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`
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`BUFFER
`PRE-
`PORT B
`
`PATH
`
`1._
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`
`1_
`4027
`
`7521
`
`I
`
`AND CONTROL
`LOOP B STATES
`
`LOOP B DATA
`
`DATA XFER CTL
`
`RECEIVE
`BUFFER
`PRE-
`PORT A
`
`PATH
`
`1_
`4026
`
`1
`3051
`
`1 -
`6422
`
`OFF-CHIP BUF DATA
`
`AND CONTROL
`LOOP A STATES
`
`LOOP A DATA
`
`l
`51'
`
`51
`
`Petitioners Microsoft Corporation and HP Inc. - Ex. 1008, p. 9
`
`

`

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`
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`
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`
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`
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`
`MAX FRM SIZE
`
`512
`
`(
`
`DITTCT/EOF
`
`MODIFIER
`
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`
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`
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`
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`
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`
`AND CONTROL
`LOOP A/B STATES
`
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`
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`
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`
`Petitioners Microsoft Corporation and HP Inc. - Ex. 1008, p. 10
`
`

`

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`
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`
`FIG.9
`
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`RECEIVE RPTR 9~41
`ROAT 95/0
`
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`
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`
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`
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`
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`RECEIVE
`
`~
`INCR
`
`DECR
`
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`
`)
`
`FRAME_OUT
`
`Petitioners Microsoft Corporation and HP Inc. - Ex. 1008, p. 11
`
`

`

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`
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`
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`
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`
`55/
`
`FIG. 10
`
`RPTR 95>59
`
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`
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`
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`
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`
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`
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`
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`
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`
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`
`Petitioners Microsoft Corporation and HP Inc. - Ex. 1008, p. 12
`
`

`

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`
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`
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`
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`
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`
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`
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`
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`
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`
`MPU DECREMENTS
`
`INCREMENTS
`
`MPU
`
`FIG. 11
`
`932
`
`COUNTER
`MUX FRM LEN
`RECEIVE
`
`INPUTS
`
`MAX SIZE 9572
`
`5931 ,l--1.-~--,
`
`592
`
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`
`DECODE
`CONTROL
`ROUTING r-5933
`
`STATE
`
`...------,
`
`BUFFER 1-----i-RECEIVE ~-----icAPTURE
`HEADER
`BUFFER 9570 r-==~:---1------------i RECEIVE
`
`READ
`V&_____.__-DECODE
`DATA__.__ FRAME
`
`9571
`
`591
`
`FRM
`
`Petitioners Microsoft Corporation and HP Inc. - Ex. 1008, p. 13
`
`

`

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`
`FIG. 12
`
`60
`
`.. TRANSFER LENGTH COUNT
`
`--RELATIVE OFFSET COUNT
`
`6024
`
`1
`
`6023
`
`I
`
`1 TRANSFER LENGTH I
`
`COUNTER
`
`609
`
`I
`RELATIVE OFFSET I
`
`COUNTER
`
`608--,
`
`SEQUENCE COUNT
`
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`
`6022
`
`I
`
`SEQUENCE COUNT
`
`COUNTER
`
`-
`
`._,/
`
`TRANSMIT A FRAME
`PORT CREDIT AVAILABLE TO
`
`DATA AVAILABLE
`
`TO TRANSMIT R_RDY
`PORT BB_CREDIT AVAILABLE
`
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`
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`
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`
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`
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`
`R_RDY CNTRS
`
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`
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`
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`
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`
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`
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`
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`
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`
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`
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`
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`
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`
`6002
`
`\
`
`6001
`
`\
`
`PORT FRAME RECEIVED
`
`PORT R_RDY TRANSMITTED
`
`Petitioners Microsoft Corporation and HP Inc. - Ex. 1008, p. 14
`
`

`

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`
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`
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`
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`
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`
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`
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`
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`
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`
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`
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`
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`
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`
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`
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`
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`
`/
`
`FIG. 13
`
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`
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`73
`
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`
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`
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`
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`
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`
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`
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`
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`
`RCV PATH CONTROLS
`
`RECEIVE PATH DATA
`
`MPU LOADABLE
`
`>
`7001
`
`SEND_FRAME
`
`Petitioners Microsoft Corporation and HP Inc. - Ex. 1008, p. 15
`
`

`

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`
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`
`BUFFER DATA
`TRANSMIT
`SINGLE-FRAME
`
`14}6
`
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`
`/73
`
`FIG. 14
`
`BUFFER
`TRANSMIT
`FRAME
`SINGLE-
`
`RAM
`
`-
`
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`
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`
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`
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`
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`
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`
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`
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`
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`
`READ
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`FRAME RPTR
`
`CONTROL
`
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`
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`
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`
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`
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`
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`
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`
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`
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`
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`
`)
`
`1403
`
`)
`
`1401
`
`XMIT STATES
`
`SEND FRAME
`
`REGISTERED MPU ADDRESS
`
`REGISTERED MPU DATA
`
`PORT B FRAME
`
`PORT A FRAME
`
`RECEIVE PATH
`DATA FROM
`
`Petitioners Microsoft Corporation and HP Inc. - Ex. 1008, p. 16
`
`

`

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`
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`
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`
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`
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`
`FIG. 15
`
`~8002
`
`COUNT=ZERO
`
`,....-. FRM LEN -82
`
`COUNTER
`
`XMIT
`
`OUTPUTS
`
`R READ CONTROL
`S TO FRAME
`
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`
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`
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`
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`
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`
`85--AND EOF GENERATOR
`
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`
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`
`OUTPUT r--
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`
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`
`l
`86
`
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`
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`
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`
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`
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`
`TRANSFER-READY PAYLOAD
`
`TRANSFER COUNTS
`
`HEADER REGISTERS
`
`FRAME BUFFER DATA
`
`MACHINE -81
`STATE
`FRAME
`XMIT
`
`~8003
`
`ENABLE COUNTER
`
`8001
`
`;
`
`SENO_FRAME
`
`Petitioners Microsoft Corporation and HP Inc. - Ex. 1008, p. 17
`
`

`

`US 6,279,057 Bl
`
`1
`COMMUNICATIONS SYSTEM HAVING
`DEDICATED FRAME BUFFERS LOCATED
`IN A CHANNEL NODE CONNECTED TO
`TWO PORTS OF THE CHANNEL NODE FOR
`RECEIVING FRAMES
`
`RELATED APPLICATIONS
`
`This application claims the benefit under 35 U.S. C. 119( e)
`of U.S. provisional application Ser. No. 60/065,920 filed
`Nov. 17, 1997, U.S. provisional application Ser. No. 60/065,
`926 filed Nov. 17, 1997, U.S. provisional application Ser.
`No. 60/065,919 filed Nov. 17, 1997, and U.S. provisional
`application Ser. No. 60/067,211 filed Dec. 1, 1997.
`This application is related to the following applications
`filed on even data herewith, each of which is incorporated by
`reference: "Method and Dedicated Frame Buffer for Loop
`Initialization and Responses" by Judy Lynn Westby,
`"Method and Apparatus for Using CRC for Data Integrity in
`On-Chip Memory" by Judy Lynn Westby, and "Method and
`Apparatus to Reduce Arbitrated-Loop Overhead" by Judy
`Lynn Westby and Michael H. Miller.
`
`FIELD OF THE INVENTION
`
`The present invention relates to the field of mass-storage
`devices. More particularly, this invention relates to an
`improved fibre-channel arbitrated-loop ("FC-AL") appara(cid:173)
`tus and method having dedicated frame buffers for receiving
`frames.
`
`BACKGROUND OF THE INVENTION
`
`30
`
`One key component of any computer system is a device
`to store data. Computer systems have many different devices
`where data can be stored. One common place for storing
`massive amounts of data in a computer system is on a disc
`drive. The most basic parts of a disc drive are a disc that is
`rotated, an actuator that moves a transducer to various
`locations over the disc, and circuitry that is used to write and
`read data to and from the disc. The disc drive also includes
`circuitry for encoding data so that it can be successfully
`retrieved from and written to the disc surface. A micropro(cid:173)
`cessor controls most of the operations of the disc drive, in
`addition to passing the data back to the requesting computer
`and taking data from a requesting computer for storing to the
`disc.
`The interface for transferring data between the disc drive
`and the rest of the computer system is typically a bus or
`channel, such as the Small Computer Systems Interface
`("SCSI"), or the Fibre Channel. Certain aspects of such
`interfaces are often standardized in order that various
`devices from different manufacturers can be interchanged
`and all can be connected to a common interface. Such
`standards are typically specified by some standards com(cid:173)
`mittee of an organization such as the American National 55
`Standards Institute ("ANSI").
`One standardized interface for exchanging data between
`various storage devices and various computers is the fibre
`channel. In some embodiments, the fibre-channel standard
`includes arbitrated loops ( described further below). In some 60
`embodiments, the fibre-channel standard supports a SCSI(cid:173)
`like protocol for controlling data transfers.
`Fibre channels represent significant advantages over
`Small Computer Standard Interface ("SCSI") designs. Fibre
`channels provide significantly higher bandwidths, currently
`up to about 106 megabytes per second, compared to between
`two and twenty megabytes per second for traditional SCSI
`
`10
`
`15
`
`20
`
`2
`designs. Fibre channels provide greater connectivity in that
`up to one-hundred twenty-six devices (including the host)
`may be connected, as compared to a maximum of seven or
`fifteen devices in typical SCSI environments. The fibre
`5 channel can be attached with a single connector and does not
`require a switch. A fibre channel using coaxial electrical
`conductors operates at distances of up to thirty meters
`between devices, and up to ten kilometers using fibre optics
`for an entire channel, as compared to a maximum total
`length ofup to twenty-five meters for SCSI environments. In
`SCSI environments, errors in data transmission are detected
`through use of parity, whereas in fibre channels, errors are
`identified by a running disparity and cyclic-redundancy(cid:173)
`code check ("CRC check") information. More information
`can be found in U.S. Pat. No. 5,802,080 entitled "CRC
`Checking Using a CRC Generator in a Multi-port Design,"
`and U.S. Pat. No. 5,663,724 entitled "16B/20B Encoder,"
`both by the present inventor, Westby, and commonly
`assigned to the present assignee Seagate Technology, Inc.,
`each of which is incorporated by reference.
`The fibre-channel arbitrated loop ("FC-AL") is an
`industry-standard system employing a byte-oriented
`DC-balanced (0,4) run-length-limited 8B/10B-partitioned
`block-transmission code scheme. The FC-AL operates at a
`25 clock frequency of 106.25 MHZ. One form of an 8B/10B
`encoder/decoder is described in U.S. Pat. No. 4,486,739
`granted Dec. 4, 1984 for "Byte Oriented DC Balanced (0,4)
`8B/10B Partitioned Block Transmission Code" by Fra(cid:173)
`naszek et al., which is incorporated by reference.
`A fibre-channel arbitrated loop ("FC-AL") allows for
`multiple devices, each called "a node," to be connected
`together. A node may be any device (a computer,
`workstation, printer, disc drive, scanner, etc.) of the com(cid:173)
`puter system having an interface allowing it to be connected
`35 to a fibre-channel "topology" (defined just below). Each
`node has at least one port, called an NL port ("node-loop
`port") to provide access to other nodes. The components that
`connect two or more ports together are collectively called a
`"topology" or a "loop." Each node communicates with all
`40 other nodes within the provided topology or loop.
`Ports are the connections in a fibre-channel node, though
`which data may pass over the fibre channel to ports of other
`nodes (the outside world). A typical fibre-channel drive has
`two ports packaged within the drive's node. Each port
`45 includes a pair of "fibers" -one to carry information into the
`port and one to carry information out of the port. Each
`"fiber" is a serial data connection, and, in one embodiment,
`each fiber is actually a coaxial wire ( e.g., coaxial copper
`conductors, used when the nodes are in close proximity to
`50 one another); in other embodiments, a fiber is implemented
`as an optical fiber for at least some of its path ( e.g., when
`nodes are separated by an appreciable distance, such as
`nodes in different cabinets or, especially, different
`buildings). The pair of fibers connected to each port (one
`carrying data into the port, the other carrying data out from
`the port) is called a "link" and is part of each topology. Links
`carry information or signals packaged in "frames" between
`nodes. Each link can handle multiple types of frames (e.g.,
`initialization, data, and control frames).
`Since each fiber carries data in one direction only, nodes
`are connected to one another along a loop, wherein the nodes
`must arbitrate for control of the loop when they have data to
`transfer. "Arbitration" is the process of coordinating the
`nodes to determine which one has control of the loop.
`65 Fibre-channel arbitrated loops attach multiple nodes in the
`loop without hubs or switches. The node ports use arbitra(cid:173)
`tion operations to establish a point-to-point data-transfer
`
`Petitioners Microsoft Corporation and HP Inc. - Ex. 1008, p. 18
`
`

`

`US 6,279,057 Bl
`
`5
`
`3
`circuit. FC-AL is a distributed topology where each port
`includes at least the minimum necessary function to estab(cid:173)
`lish the circuit. The arbitrated-loop topology is used to
`connect any number of nodes between two and one-hundred
`twenty-six (126) node ports.
`In some embodiments, each node includes dual ports
`( each connected to a separate loop) which provide
`redundancy, so that if one loop fails, the other one can fulfill
`the loop duties. Dual ports also allow two hosts (e.g., two
`host computers) to share a single drive.
`In typical first- and second-generation FC-AL drives, the
`two ports shared the frame-validation and frame-generation
`logic. This meant that if one port was receiving or trans(cid:173)
`mitting a frame, the alternate port was effectively busy
`(since it could not simultaneously use the frame-validation 15
`and frame-generation logic), and the alternate port was thus
`forced to deny its host-bus adapter permission to send
`frames. Some host-bus adapters would continuously have to
`arbitrate and attempt to send a frame over and over until the
`primary port closed. Also, the drive was only able to transmit 20
`on one port at a time. In some cases, an outbound data
`transfer on a given port would have to be paused in order to
`send a response or perform loop initialization on the other
`(alternate) port.
`CRC Background
`Most data-transmission operations employ error checking
`by which an error code, based on the header and payload
`data of the transmission, is checked to verify the integrity of
`the received header and payload data. One such error(cid:173)
`checking scheme employs cyclic-redundancy-code ("CRC") 30
`information. A typical circuit employing CRC error check(cid:173)
`ing will include a CRC checker to verify the integrity of
`received data words and a CRC generator to generate CRC
`information for digital words being transmitted. In multi(cid:173)
`port designs, a CRC checker and a CRC generator must be 35
`available for each port to handle verification of each
`received digital word and to generate CRC information for
`each digital word being transmitted. In many applications,
`the circuit or loop-interface module transmits on only one
`port at a time. For example, a disc-drive subsystem com- 40
`municating through a multi-port interface module to a
`computer network would prepare and transmit data through
`only a single port at any given time. However, the loop(cid:173)
`interface module might attempt to receive data through
`plural ports at a given time.
`One approach to reception of data through plural ports is
`to simply inhibit reception of data through other ports when
`one port is already receiving data. This approach allows
`common resources, such as the CRC checker or the frame(cid:173)
`validation logic, to be shared among the several ports. The 50
`first port to receive data seizes use of the common resources
`to the exclusion of the other ports, and the other ports are
`inhibited from receiving data. Hence, incoming data cannot
`be received on the other ports and the other ports are limited
`to the function of data transmission. This approach resulted 55
`in the other ports receiving a "busy" condition in response
`to requests to transmit data, and necessitated repeating the
`sequence to request transmission of data again and again,
`until the first port completed the operation it was performing
`and freed-up the common resource.
`Loop Initialization Background
`In plural loop networks, it is necessary to "initialize" a
`loop after an error condition is detected, as well as when a
`loop-interface module is connected into the channel, or
`when the fibre channel is powered up. Initialization is 65
`ordinarily accomplished by transmitting loop-initialization
`data onto the loop. However, if a loop-interface module
`
`4
`connected to the loop is already receiving data through a port
`connected to another loop, that loop-interface module might
`not be able to receive the loop-initialization data. Normally,
`under such circumstances the data transfer is suspended, and
`loop initialization is allowed to proceed first. In other
`instances, the loop-initialization sequence will stall, and go
`into a continuous-retry mode until the other loop ( of the
`dual-loop node) completes receiving data. Moreover, if the
`loop-interface modules can receive only on one loop at a
`10 time, the modules cannot receive data through another port
`while loop initialization is occurring on one channel.
`Fiber links have received considerable attention in con-
`nection with transmission of data between various devices of
`a computer network. More particularly, fibre channels offer
`significant advantages over Small Computer System Inter(cid:173)
`face ("SCSI") buses in terms of higher bandwidth, greater
`connectability, greater ease of attachment of modules,
`greater transmission distance, and other factors. For
`example, a typical SCSI bus is able to handle up to fifteen
`(15) modules with a total distance of up to about 25 meters,
`whereas a fibre channel can handle up to one-hundred
`twenty-six (126) modules with a distance of about thirty
`meters between modules using electrical transmission, or up
`to ten kilometers using optical transmission. Thus, in order
`25 to achieve a data-transfer rate of, for example, a terrabyte/
`second peak, it would require up to seventy SCSI buses but
`would need only about ten fibre channels. It is important that
`a channel be brought up to oper