`United States Patent
`[19J
`
`Fijolek et al.
`
`US006058421A
`6,058,421
`[11]Patent Number:
`May 2, 2000
`[45] Date of Patent:
`
`I 1111111111111111 11111 1111111111 111111111111111 1111111111 111111111111111111
`
`5,778,181 7/1998 Hidary et al. ........................... 709/218
`
`
`
`METHOD AND SYSTEM FOR ADDRESSING
`[54]
`
`
`
`5,790,198 8/1998 Roop et al. ............................. 348/460
`
`NETWORK HOST INTERFACES FROM A
`
`
`
`5,790,548 8/1998 Sistanizadeh et al. .................. 370/401
`CABLE MODEM USING DHCP
`
`
`
`5,790,677 8/1998 Fox et al. .................................. 705/78
`
`
`5,799,086 8/1998 Sudia ........................................ 705/76
`Inventors: John G. Fijolek, Naperville; Nurettin
`
`
`
`[75]
`
`
`
`B. Beser, Evanston; Philip T.
`
`
`Robinson, Barrington, all of Ill.
`
`(List continued on next page.)
`
`
`
`
`
`OTHER PUBLICATIONS
`
`
`[73]Assignee:
`
`
`3Com Corporation, Santa Clara, Calif.
`"Cable Modem to Customer Premise Equipment Interface
`
`
`
`
`
`Specification (Interim) SP-CMCI-I02-980317", Multime­
`
`
`
`dia Cable Network Systems (MCNS) Holdings, L.P., 1998,
`
`pp. II to 40.
`
`[21] Appl. No.: 09/018,784
`
`[22] Filed:Feb. 4, 1998
`
`[56]
`
`Attorney, Agent, or Firm-McDonnell Boehnen Hulbert &
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`
`
`(List continued on next page.)
`Int. Cl.7 ................................................... G06F 15/173
`
`[51]
`
`
`
`
`U.S. Cl. .......................... 709/225; 709/203; 709/202;
`[52]
`Primary Examiner-Frank J. Asta
`
`
`
`
`
`709/217; 709/218; 709/219; 709/226; 370/312;
`
`Assistant Examiner-Beatriz Prieto
`
`
`
`370/352; 370/389; 370/432; 370/475; 348/6;
`
`
`
`
`
`
`
`
`348/734; 359/164; 359/165; 364/705.05
`
`
`Berghoff; Stephen Lesavich
`
`
`Field of Search ..................................... 709/224, 203,
`[58]
`ABSTRACT
`[57]
`
`
`709/202, 217, 218, 219, 226, 227, 231,
`
`
`
`238, 245; 711/200; 370/312, 352, 389,
`A method and system are provided to allow a cable modem
`
`
`
`
`432, 475; 364/705.05; 348/6, 734; 359/164,
`
`
`
`
`to discover an address of a network host interface on a cable
`165
`
`
`
`
`television network to connect the cable modem to a data
`
`
`
`network (e.g., the Internet). The cable modem is used in a
`
`
`data-over-cable system with telephony return. The cable
`
`
`
`modem is connected to a cable television network over a
`
`
`
`downstream cable data channel and connected to a public
`
`
`5/1991 Edwards, Jr. ........................... 713/200
`5,014,234
`
`
`
`switched telephone network over a serial telephone line. The
`
`
`8/1992 Corbin .................................... 713/200
`5,138,712
`
`
`method provides a way for the cable modem to determine
`
`9/1994 Moura et al. .
`5,347,304
`
`
`
`
`
`the address of network host interfaces ( e.g., Internet Protocol
`
`
`
`8/1995 Northcutt et al. ...................... 709/219
`5,442,749
`
`
`
`hosts) available on the cable television system via the
`
`1/1996 Majeti et al. .
`5,488,412
`
`
`
`
`upstream channel connected to public switched telephone
`
`
`2/1996 Inoue ................................. 340/870.39
`5,489,897
`
`
`
`network. The method includes using existing Dynamic Host
`
`12/1996 Schneider et al. ...................... 379/399
`5,583,931
`("DHCP")
`
`12/1996 Moura et al. .
`5,586,121
`
`
`
`Configuration Protocol messages and message
`
`
`2/1997 Schneider et al. ...................... 379/399
`5,600,717
`
`
`
`fields to discover network host interfaces available on the
`
`
`2/1997 Schneider et al. ...................... 379/399
`5,606,606
`
`
`
`cable television system even though the cable modem only
`3/1997 Carr et al. .
`5,608,446
`
`
`
`has downstream connection from the cable television net­
`
`
`4/1997 Schneider et al. ...................... 379/399
`5,623,542
`
`
`work. The method and are used without changes to DHCP
`
`
`
`4/1997 Vu ........................................... 713/201
`5,623,601
`
`
`and can also be used in a data-over-cable system without
`
`6/1997 Newlin et al. .......................... 370/465
`5,636,211
`telephony return.
`
`
`10/1997 Majeti et al. .
`5,675,732
`
`1/1998 Bondi ...................................... 709/224
`5,710,885
`
`
`6/1998 Wagner et al. .......................... 455/3.1
`5,761,602
`
`25 Claims, 23 Drawing Sheets
`
`326
`
`Page 1 of 41
`
`

`

`6,058,421
`Page 2
`
`U.S. PATENT DOCUMENTS
`
`
`
`5,805,804 9/1998 Laursen et al. ............................. 348/7
`5,818.845 10/1998 Moura et al. .
`... 370/449
`5,819,042 10/1998 Hansen ......
`... 709/222
`5,828,655 10/1999 Moura et al. .
`... 370/326
`5,854,901 12/1998 Cole et al. ...
`... 709/245
`5,859,852
`1/1999 Moura et al. .
`... 370/449
`5,864,679
`1/1999 Kanai et al. ............................ 709/238
`5,870,134 2/1999 Laubach et al. .......................... 348/12
`5,872,523 2/1999 Dellaverson et al.
`... 340/825.52
`5,922,049 7/1999 Radia et al. ............................ 709/220
`5,923,659 7/1999 Curry et al. .
`... 370/401
`5,958,007 9/1999 Lee et al. ................................ 709/219
`OTHER PUBLICATIONS
`“Operations Support System Interface Specification Base
`line Privacy Interface MIB (Interim) SP-OSSI-B-
`PI-I01-980331", MCNS Holdings, L.P., 1998, pp. II to 33.
`“Cable Modem Termination System-Network Side Inter
`face Specification (Interim Specification) SP-CMTS-N-
`SIIO1-960702, MCNS Holdings, L.P., 1996, pp. II to 13.
`“Removable Security Module Interface Specification
`(Interim Specification) SP-RSMI-I01-980204", MCNS
`Holdings, L.P., 1997, pp. II to 48.
`
`“Baseline Privacy Interface Specification (Interim) SP-B-
`PI-I01–970922, MCNS Holdings, L.P., 1997, pp. II to 66.
`“Operations Support System Interface Specification
`(Interim) SP-OSSII01–970403", MCNS Holdings, L.P.,
`1997, pp. 1 to 30.
`“Radio Frequency Interface Specification (Interim Specifi
`cation) SP-RFI-I02-971008”, MCNS Holdings, L.P., 1997,
`pp. II to 186.
`“Cable Modem Technology Return Interface Specification
`(Interim) SP-CMTRI-I01–970804", MCNS Holdings, L.P.,
`1997, pp. II to 74.
`“Security System Specification (Interim Specification)
`SP-SSI-I01–970506”, MCNS Holdings, L.P., 1997, pp. II to
`103.
`“Internet Engineering Task Force, Request for Comments
`2131, Dynamic Host Configuration Protocol (DHCP), Mar.
`1997, pp. 1 to 42.
`S. Adiraju, J. Fijolek, IPCDN Telephony Return MIB,
`Internet Engineering Task Force, Internet
`Draft,
`“<draft-ipcdn-tri-mib-00.0>.txt,” Mar. 23, 1998, pp. 1-26.
`
`Page 2 of 41
`
`

`

`U.S. Patent
`
`May 2, 2000
`
`Sheet 1 of 23
`
`6,058,421
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`F.G. 1
`...A.2s.
`TELEPHONY
`UPSTREAM
`REMOTE
`ACCESS
`CONCENTRATOR
`(TRAC) 24
`
`10
`
`/
`
`
`
`CABLE MODEM
`TERMINATION
`
`SYSTEM
`
`(CMTS) 12
`HEAD END
`OF
`CABLE SYSTEM
`
`
`
`
`
`...
`
`.
`
`. .
`
`.
`
`a
`
`DOWNSTREAM (CM)
`(IUPSTREAM)
`
`
`
`201CPE
`
`Page 3 of 41
`
`

`

`U.S. Patent
`
`May 2, 2000
`
`Sheet 2 of 23
`
`6,058,421
`
`FIG. 2
`
`36
`
`TFTP
`
`DHCP
`
`UDP
`MGMT
`
`TRANSPORT
`AYER
`58
`
`NETWORK
`LAYER
`52
`
`44
`
`DATA LINK
`LAYER
`42
`
`50
`
`RF
`INTERFACE 40
`
`DOWNSTREAM
`(UPSTREAM ALSOIF
`TELEPHONY RETURNS
`NOTUSED)
`
`
`
`MODEM.
`INTERFACE 48
`
`PHYSICAL
`LAYER
`38
`
`UPSTREAM
`
`Page 4 of 41
`
`

`

`U.S. Patent
`
`May 2, 2000
`
`Sheet 3 of 23
`
`6,058,421
`
`70
`
`76
`
`FG. 3
`
`TCD
`
`MAC MANAGEMENT HEADER
`
`SERVICE PROVIDER DESCRIPTORS ENCODED AS TLV DATA
`
`FG. 4
`
`TS
`
`
`
`MAC MANAGEMENT HEADER
`
`DOWNSTREAM CABLE CHANNEL PADDRESS
`
`REGISTRATION PADDRESS
`
`CMTS BOOT TIME
`
`DOWNSTREAM
`CHANNELD
`
`VENDOR SPECIFIC
`ENCODED AS TV
`DATA
`
`Page 5 of 41
`
`

`

`U.S. Patent
`
`May 2, 2000
`
`Sheet 4 of 23
`
`6,058,421
`
`FIG.S
`
`92
`
`/
`
`RECEIVE A SELECTION INPUT ON A FIRST NETWORK
`DEVICE FROMA DOWNSTREAM CONNECTION FROMA
`FIRST NETWORK CONTAINING A FIRST CONNECTION
`ADDRESS FOR THE FIRST NETWORK
`
`CREATE A FIRST MESSAGE WITH A FIRST MESSAGE TYPE
`ON THE FIRST NETWORK DEVICE HAVING THE FIRST
`CONNECTION ADDRESS IN A FIRST FELD
`
`SEND THE FIRST MESSAGE FROM THE FIRST NETWORK
`DEVICE OVER ANUPSTREAM CONNECTION TO A SECOND
`NETWORK
`
`94
`
`96
`
`98
`
`
`
`
`
`
`
`
`
`
`
`FORWARD THE MESSAGE FROM THE SECOND NETWORK
`TO A PLURALITY OF NETWORK HOST INTERFACES
`ASSOCATED WITH THE FIRST NETWORK USING THE FIRST
`CONNECTION ADDRESS FROM THE FIRST MESSAGE
`
`100
`
`CREATE ONE OR MORE SECOND MESSAGES WITH A
`SECOND MESSAGE TYPE FROM THE ONE OR MORE
`NETWORK HOST INTERFACES AND FORWARD THEM TO
`THE FIRST NETWORK
`
`102
`
`
`
`FORWARD THE ONE ORMORE SECONOMESSAGES FROM
`THE FIRST NETWORK TO THE FIRST NETWORK DEVICE
`OVER THE DOWNSTREAM CHANNEL
`
`104
`
`SELECT ONE NETWORK HOST INTERFACE FROM THE FIRST
`NETWORK DEVICE USING THE ONE OR MORE SECOND
`MESSAGES AND ESTABLISHA VIRTUAL CONNECTION TO A 106
`THIRD NETWORK
`
`
`
`Page 6 of 41
`
`

`

`U.S. Patent
`
`May 2, 2000
`
`Sheet 5 of 23
`
`6,058,421
`
`
`
`F.G. 6
`
`108
`
`CADDR
`
`YIADDR
`
`SADDR
`
`GADDR
`
`CHADDR
`
`OPTIONS
`
`Page 7 of 41
`
`

`

`U.S. Patent
`
`May 2, 2000
`
`Sheet 6 of 23
`
`6,058,421
`
`FG. 7A
`
`140
`
`/
`
`CM GENERATES A DHCP DSCOVER MESSAGE AND SENDS
`IT UPSTREAM VIA PSTN TO TRAC
`
`142
`
`
`
`
`
`
`
`TRAC RECEIVES DHCP DSCOVER MESSAGE AND
`BROADCASTS THE MESSAGE TO ITS LOCAL NETWORK
`CONTAINING MULTIPLE DHCP PROXES USING THE GADDR
`FIELD FROM THE DHCP DISCOVER MESSAGE
`
`MULTIPLE DHCP PROXES RECOGNIZE THE DHCP
`DISCOVER MESSAGE AND FORWARDS IT USING THE
`GADDR FIELD TO MULTIPLE DHCP SERVERS ASSOCATED
`WITH MULTIPLE NETWORK HOST INTERFACES
`
`146
`
`MULTIPLE NETWORK HOST INTERFACES RECEIVE THE
`DHCP DISCOVER MESSAGE AND GENERATE ONE OR MORE
`DHCP OFFER MESSAGES IF THEIR ASSOCATED
`INTERFACES CAN PROVIDE THE SERVICE REGUESTED IN
`THE DHCP DSCOVER MESSAGE
`
`
`
`148
`
`G.
`
`Page 8 of 41
`
`

`

`U.S. Patent
`
`May 2, 2000
`
`Sheet 7 of 23
`
`6,058,421
`
`FIG. 7B
`
`
`
`CMTS RECEIVES ONE ORMORE DHCP OFFER MESSAGES
`FROM ONE OR MORE NETWORK HOST INTERFACES VIA
`DHCP SERVERS
`
`CMTS SENDS CM ONE OR MORE DHCP OFFER MESSAGES
`VIA ADOWNSTREAM CHANNEL ON THE CABLE NETWORK
`
`CM SELECTS ONE OF THE DHCP OFFER MESSAGES FOR
`DATASERVICE AND USES THE YADDR FIELD TO
`ESTABLISHA VIRTUAL DATA CONNECTION TO A DATA
`NETWORK
`
`Page 9 of 41
`
`

`

`U.S. Patent
`
`May 2, 2000
`
`Sheet 8 of 23
`
`6,058,421
`
`
`
`
`
`
`
`
`
`
`
`ess as sees is is
`
`b
`
`see st 26.
`
`30
`
`TELCO REMOTE
`ACCESS
`CONCENTRATOR
`(TRAC) 24
`
`UPSTREAM
`
`156
`
`/
`
`
`
`
`
`
`
`
`
`
`
`
`
`CABLE MODEM
`TERMINATION
`SYSTEM
`CABLE 20
`(CMTS)12
`14 MODEM
`essess sess
`to es
`esse in DOWNSTREAM (CM)
`HEADEND
`(IUPSTREAM)
`OF CABLE
`NETWORK
`
`
`
`CPE
`
`Page 10 of 41
`
`

`

`U.S. Patent
`
`May 2, 2000
`
`Sheet 9 of 23
`
`6,058,421
`
`FIG. 9
`
`164
`
`s
`
`-
`
`DHCP
`TC PROXIES
`
`158
`
`DHCP
`SERVERS
`160
`
`CMTS
`12
`
`Discover) BROADCAs
`Discover)
`
`NH
`162
`
`Discover). UNICAs Es)
`
`152
`
`
`
`CM
`CHOOSESA
`SINGLE NH
`OFFER
`
`154
`
`Page 11 of 41
`
`

`

`U.S. Patent
`
`May 2, 2000
`
`Sheet 10 of 23
`
`6,058,421
`
`FIG. 10A
`
`166
`/
`
`FIRST NETWORK DEVICE RECEIVES MULTIPLE FIRST
`MESSAGES FROMA FIRST NETWORK ON ADOWNSTREAM
`CONNECTION SENT BY MULTIPLE NETWORK HOST
`INTERFACES OFFERING CONNECTION SERVICES TO A
`THIRD NETWORK
`
`168
`
`FIRST NETWORK DEVICE SELECTS ONE OF THE NETWORK
`HOST INTERFACES USING THE MULTIPLE FIRST MESSAGES
`TO PROVIDE A CONNECTION ADDRESS FOR THE THIRD
`NETWORK
`
`170
`
`FIRST NETWORK DEVICE CREATES A SECOND MESSAGE
`INCLUDING AN IDENTIFIER FOR THE SELECTED NETWORK
`HOST INTERFACE AND A CONNECTION ADDRESS FOR THE
`FIRST NETWORK TO ACCEPT CONNECTION SERVICES
`OFFERED IN THE SELECTED FIRST MESSAGE
`
`172
`
`FIRST NETWORK DEVICE SENDS THE SECOND MESSAGE
`OVER THE UPSTREAM CONNECTION TO THE SECOND
`NETWORK
`
`174
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`THE SECOND NETWORK FORWARDS THE SECONO
`MESSAGE TO MULTIPLE NETWORKHOST INTERFACES
`AVAILABLE ON THE FIRST NETWORK
`
`176
`
`O A
`FIG.
`10B
`
`Page 12 of 41
`
`

`

`U.S. Patent
`
`May 2, 2000
`Sheet 11 of 23
`FG, 10B
`
`6,058,421
`
`A NETWORK HOST INTERFACE ON THE FIRST NETWORK
`RECOGNIZES ITS DENTIFIER IN THE SECOND MESSAGE
`FROM THE FIRST NETWORK DEVICE
`
`THE SELECTED NETWORK HOST INTERFACE THAT
`RECOGNIZEDITSIDENTIFIER SENDS A THIRD MESSAGE TO
`THE FIRST NETWORK FOR THE FIRST NETWORK DEVICE
`
`THE FIRST NETWORKSTORES A CONNECTION ADDRESS
`FOR THE NETWORK HOST INTERFACE IN AN ADDRESSING
`TABLE
`
`178
`
`180
`
`182
`
`THE FIRST NETWORK FORWARDS THE THIRD MESSAGE TO
`THE FIRST NETWORK DEVICE ON ADOWNSTREAM
`CONNECTION AND HAS THE NECESSARY ADDRESS TO
`FORWARD DATA RECEIVED FROM THE THIRD NETWORK TO
`THE FIRST NETWORK DEVICE
`
`184
`
`THE FIRST NETWORK DEVICE RECEIVES THE THIRD
`MESSAGE AND HAS ESTABLISHED A VIRTUAL CONNECTION
`TO RECEIVE DATA FROM THE THIRD NETWORK USING THE
`SELECTED NETWORK HOST INTERFACE ON THE FIRST
`NETWORK
`
`186
`
`
`
`
`
`Page 13 of 41
`
`

`

`U.S. Patent
`
`May 2, 2000
`
`Sheet 12 of 23
`
`6,058,421
`
`FIG. 11A
`
`188
`/
`CM RECEIVES MULTIPLE DHCPOFFER MESSAGES FROM
`CMTS ON ADOWNSTREAM CONNECTION VIA CABLE
`NETWORKSENT BY MULTIPLE DHCP SERVERS FOR
`MULTIPLE NETWORK HOST INTERFACES OFFERING
`CONNECTION SERVICES TO THE DATA NETWORK
`
`190
`
`CM SELECTS ONE OF MULTIPLE DHCP OFFER MESSAGES
`TO PROVIDEA CONNECTION TO THE DATA NETWORK
`
`192
`
`CM CREATES A DHCP REQUEST MESSAGE INCLUDING AN
`IDENTIFIER FOR ADHCP SERVER ASSOCATED WITH THE
`SELECTED NETWORKHOST INTERFACE ANDA
`CONNECTION ADDRESS FOR THE FIRST NETWORK
`
`194
`
`CM SENDS THE DHCP REQUEST MESSAGE OVER THE
`UPSTREAM CONNECTION VIA THE PSTN TO THE TRAC
`
`196
`
`
`
`
`
`
`
`
`
`
`
`THE TRAC FORWARDS THE DHCP REQUEST MESSAGE TO
`MULTIPLE DHCP SERVERS AVAILABLE ON THE CMTS
`
`198
`
`O A
`FIG.
`11B
`
`Page 14 of 41
`
`

`

`U.S. Patent
`
`May 2, 2000
`
`Sheet 13 of 23
`
`6,058,421
`
`FIG. 11B
`
`ONE OR MORE PROXESIDENTIFY THE DHCP REQUEST
`MESSAGE AND SEND IT TO A SELECTED DHCP SERVER
`AVAILABLE ON THE CMTS
`
`200
`
`A SELECTED DHCP SERVER RECOGNIZES ITS DENTIFIER
`AND THE PADDRESS OF ANASSOCATED NETWORKHOST
`INTERFACE
`
`202
`
`THE SELECTED DHCP SERVER CREATES AND SENDS A
`DHCPACK MESSAGE TO THE CMTS
`
`THE CMTS RECEIVES THE DHCPACK MESSAGE FROM THE
`SELECTED DHCP SERVER
`
`204
`
`2O6
`
`CMTS UPDATES AN INTERNAL ARP TABLE WITH THE IP
`ADDRESS OF THE NETWORK iNTERFACE HOST AND THE
`MAC ADDRESS OF THE CM
`
`208
`
`
`
`
`
`CMTS SENDS THE DHCPACK TO THE CM
`
`210
`
`CMRECEIVES THE DHCP ACK AND HAS THE ADDRESSES
`NECESSARY TO COMPLETEAVIRTUAL CONNECTION TO
`THE DATA NETWORK
`
`212
`
`Page 15 of 41
`
`

`

`U.S. Patent
`
`May 2, 2000
`
`Sheet 14 of 23
`
`6,058,421
`
`F.G. 12
`
`214
`
`DHCP
`PROXIES
`
`158
`
`DHCP
`SERVERS
`160
`
`CMTS
`12
`
`r
`
`Discover) s: if)
`REQUEST) r UNICAST
`
`NHe
`
`UNICAST
`
`
`
`
`
`210
`
`CMTS
`UPDATES
`TABLES
`
`208
`
`TAC
`Discover)
`
`BROADCAST
`
`
`
`
`
`
`
`CM
`CHOOSESA
`SINGLE NH
`OFFER
`
`BROADCAST
`
`CM HAS
`VERIFED
`IP ADDRESS
`FOR NH
`212
`
`Page 16 of 41
`
`

`

`U.S. Patent
`
`May 2, 2000
`
`Sheet 15 of 23
`
`6,058,421
`
`
`
`F.G. 13A
`
`START
`
`FIRST NETWORK DEVICE CREATES A FIRST MESSAGE WITH
`A FRST MESSAGE FIELD FOR A FIRST CONNECTION
`ADDRESS TO DISCOVER NETWORK HOST INTERFACES ON
`A FIRST NETWORK TO CONNECT FIRST NETWORK DEVICE
`TO A THIRD NETWORK WITH A VIRTUAL CONNECTION
`
`FIRST NETWORK DEVICE SENDS FIRST MESSAGE TO
`SECOND NETWORK DEVICE
`
`FIRST MESSAGE
`FIELD ZERO7
`
`SECOND NETWORK DEVICE ADDS ITS OWN CONNECTION
`ADDRESS TO THE FIRST MESSAGE FIELD IN THE FIRST
`MESSAGE
`
`SECOND NETWORK DEVICE FORWARDS THE FIRST
`MESSAGE ON ANUPSTREAM CONNECTION TO THE
`SECOND NETWORK
`
`THE SECOND NETWORK FORWARDS THE FIRST MESSAGE
`TO ONE OR MORE NETWORK HOST INTERFACES ON THE
`FIRST NETWORK
`
`Page 17 of 41
`
`

`

`U.S. Patent
`
`May 2, 2000
`
`Sheet 16 of 23
`
`6,058,421
`
`FIG. 13B
`
`ONE OR MORE NETWORK HOST INTERFACES THAT CAN
`OFFER THE REGUESTED SERVICE SENDA SECOND
`MESSAGE WITH A SECOND CONNECTION ADDRESS INA
`SECOND FELD TO THE FIRST NETWORK
`
`230
`
`
`
`
`
`THE FIRST NETWORK FORWARDS THE ONE OR MORE
`SECOND MESSAGES TO THE SECOND NETWORK DEVICE
`ON ADOWNSTREAM CONNECTION
`
`232
`
`THE SECOND NETWORK DEVICE FORWARDS THE ONE OR
`MORE SECOND MESSAGES TO THE FIRST NETWORK
`DEVICE
`
`234
`
`FIRST NETWORK DEVICE SELECTS ONE OF THE NETWORK
`HOST INTERFACES ON THE FIRST NETWORK USING THE
`ONE OR MORE SECOND MESSAGES TO ESTABLISHA
`VIRTUAL CONNECTION TO THE THIRD NETWORK
`
`236
`
`Page 18 of 41
`
`

`

`U.S. Patent
`
`May 2, 2000
`
`Sheet 17 of 23
`
`6,058,421
`
`FIG. 14A
`
`240
`/
`
`
`
`
`
`FIRST NETWORK DEVICE RECEIVES ONE OR MORE
`SECOND MESSAGES FROM ONE OR MORE NETWORK
`HOST INTERFACES ON A FIRST NETWORK
`
`242
`
`FIRST NETWORK DEVICE SELECTS ONE OF THE NETWORK
`HOST INTERFACES ON THE FIRST NETWORK USING THE
`ONE ORMORE SECOND MESSAGES
`
`FIRST NETWORK DEVICE CREATES A THIRD MESSAGE
`WITH A CONNECTION ADDRESS IN A FIRST FIELD AND AN
`IDENTIFIER IN A SECOND FELD TO DENTIFY THE
`SELECTED NETWORKHOST
`
`FIRST NETWORK DEVICE SENDS THE THIRD MESSAGE TO
`THE SECOND NETWORK DEVICE
`
`SECOND NETWORK DEVICE SENDS THE THIRD MESSAGE
`TO THE SECOND NETWORKONANUPSTREAM
`CONNECTION
`
`246
`
`248
`
`250
`
`THE SECOND NETWORK FORWARDS THE THIRD MESSAGE
`TO ONE ORMORE NETWORK HOST INTERFACES ON THE
`FIRST NETWORK
`
`252
`
`O A
`FIG.
`14B
`
`Page 19 of 41
`
`

`

`U.S. Patent
`
`May 2, 2000
`
`Sheet 18 of 23
`
`6,058,421
`
`FG, 14B
`
`A SELECTED NETWORK HOST INTERFACE RECOGNIZES ITS
`IDENTIFIER IN THE THIRD MESSAGE
`
`THE SELECTED NETWORK HOST CREATES A FOURTH
`MESSAGE WITH A CONNECTION ADDRESS FOR THE
`SELECTED NETWORK HOST IN A THIRD MESSAGE FIELD
`AND SENDS IT TO THE FIRST NETWORK
`
`254
`
`256
`
`THE FIRST NETWORKSTORES THE CONNECTION ADDRESS
`FOR THE SELECTED NETWORK HOST IN ITS ROUTING
`TABLES
`
`258
`
`THE FIRST NETWORK FORWARDS THE FOURTH MESSAGE
`TO THE SECOND NETWORK DEVICE ON AN DOWNSTREAM
`CONNECTION
`
`260
`
`THE SECOND NETWORK DEVICE STORES THE
`CONNECTION ADDRESS FOR THE SELECTED NETWORK
`HOST IN ITS ROUTING TABLES
`
`262
`
`THE SECOND NETWORK DEVICE FORWARDS THE FOURTH
`MESSAGE TO THE FIRST NETWORK DEVICE
`
`264
`
`THE FIRST NETWORK DEVICE ESTABLISHES AVIRTUAL
`CONNECTION TO THE THIRD DATANETWORKWITH THE
`SELECTED NETWORK HOST INTERFACE ON THE FIRST
`NETWORKAND THE SECOND NETWORK DEVICE
`
`
`
`266
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`Page 20 of 41
`
`

`

`U.S. Patent
`
`May 2, 2000
`
`Sheet 19 of 23
`
`6,058,421
`
`F.G. 15A
`
`s
`
`
`
`
`
`
`
`
`
`CPE CREATES A DHCP DISCOVER MESSAGE AND
`BROADCASTS THE DHCP DISCOVER MESSAGE ON ITS
`LOCAL NETWORK
`
`CMRECEIVES THE DHCP DSCOVER MESSAGE FROM THE
`CPE
`
`GADDR-FELD ZERO
`
`YES
`
`CMADDS ITS OWN PADDRESS TO THE GADDR-FIELD IN
`THE DHCP DSCOVER MESSAGE
`
`CMBROADCASTS THE DHCP DISCOVER MESSAGE ON AN
`UPSTREAM CONNECTION TO TRAC WA PSTN
`
`DHCP PROXES ASSOCIATED WITH THE TRAC FORWARD
`THE DHCP DISCOVER MESSAGE TO DHCP SERVERS
`ASSOCATED WITH NETWORK HOST INTERFACES
`AVAILABLE ON CMTS
`
`28O
`
`Page 21 of 41
`
`

`

`U.S. Patent
`
`May 2, 2000
`
`Sheet 20 of 23
`
`6,058,421
`
`FIG. 1SB
`
`DHCP SERVERS ASSOCIATED WITH NETWORK HOST
`INTERFACES AVAILABLE ON CMTS GENERATE DHCP
`OFFER MESSAGES
`
`282
`
`CMTS RECEIVES THE DHCP OFFER MESSAGES FROM THE
`DHCP SERVERS AND FORWARDS THEM ONA
`DOWNSTREAM CONNECTION TO THE CM
`
`284
`
`CM FORWARDS THE DHCP OFFER MESSAGES TO THE CPE
`
`CPE RECEIVES THE DHCP OFFER MESSAGES FROM THE
`CM
`
`CPE SELECTS ANETWORK HOST INTERFACE USING THE
`ONE OR MORE DHCP OFFER MESSAGES
`
`THE CPE ESTABLISHES AVIRTUAL CONNECTION TO THE
`DATANETWORK WITH THE SELECTED NETWORK HOST
`INTERFACE ON THE CMTS VIA THE CM
`
`286
`
`288
`
`290
`
`292
`
`
`
`
`
`
`
`Page 22 of 41
`
`

`

`U.S. Patent
`
`May 2, 2000
`
`Sheet 21 of 23
`
`6,058,421
`
`FIG. 16A
`
`294
`Y
`
`CPE RECEIVES ONE OR MORE DHCP OFFER MESSAGES
`FROM ONE OR MORE NETWORK HOST INTERFACES ON
`CMTS
`
`296
`
`CPE SELECTS ONE OF THE NETWORK HOST INTERFACES
`ON CMTS USING THE ONE OR MORE SECOND MESSAGES
`
`CPE CREATES A DHCP REQUEST MESSAGE WITH A
`CONNECTION ADDRESS IN A FIRST FELD AND AN
`INDENTURE IN A SECOND FIELD TO DENTIFY THE
`SELECTED NETWORK HOST
`
`CPE SENDS THE DHCP REQUEST MESSAGE TO THE CM
`
`CM FORWARDS THE DHCP DISCOVER MESSAGE TO THE
`TRAC WA PSTN ON AN UPSTREAM CONNECTION
`
`
`
`THE TRAC BROADCASTS THE DHCP DSCOVER MESSAGE
`ONTS LOCAL NETWORK
`
`298
`
`300
`
`302
`
`304
`
`306
`
`O A
`FIG.
`16B
`
`Page 23 of 41
`
`

`

`U.S. Patent
`
`May 2, 2000
`
`Sheet 22 of 23
`
`6,058,421
`
`F.G. 16B
`
`
`
`
`
`
`
`
`
`
`
`ONE OR MORE DHCP PROXIES ASSOCATED WITH TRAC
`FORWARD THE DHCP REGUEST MESSAGE TO ONE OR
`MORE DHCP SERVERS ASSOCATED WITH ONE OR MORE
`NETWORK HOST INTERFACES AVAILABLE ON THE CMTS 308
`
`A DHCP SERVER RECOGNIZES AN IDENTIFIER FOR A
`NETWORK HOST INTERFACE SELECTED IN THE DHCP
`RECRUEST MESSAGE
`
`THE DHCP SERVER ASSOCATED WITH THE SELECTED
`NETWORK HOST INTERFACE GENERATES A DHCPACK
`MESSAGE AND SENDS IT TO THE CMTS
`
`CMTS RECEIVES THE DHCPACK
`
`THE CMTS STORES A CONNECTION ADDRESS FOR THE
`SELECTED NETWORK HOST INTERFACE IN ITS ROUTING
`TABLES
`
`CMTS SENDS THE DHCPACK TO THE CM
`
`CM STORES THE CONNECTION ADDRESS FOR THE
`SELECTED NETWORK HOST INTERFACE IN ITS ROUTING
`TABLES
`
`CM SENDS THE DHCPACK TO THE CPE
`
`THE CPE RECEIVES THE DHCPACK ESTABLISHES A
`VIRTUAL CONNECTION TO THE DATANETWORK
`
`310
`
`312
`
`314
`
`316
`
`318
`
`320
`
`322
`
`324
`
`Page 24 of 41
`
`

`

`U.S. Patent
`
`May 2, 2000
`
`Sheet 23 of 23
`
`6,058,421
`
`FIG. 17
`TRAC 241
`DHCP
`PROXIES
`
`326
`/
`
`
`
`DHCP
`SERVERS
`
`cyS
`
`Discover)
`
`c
`
`
`
`BROADCAS
`
`278
`
`Discover) re, is,
`
`NHe
`
`UNICAST
`
`
`
`
`
`CPE
`CHOOSESA
`SINGLE NH
`OFFER
`
`REQUEST) BROADAR
`REQUEST)
`
`
`
`CMUPDATES
`TABLES
`
`320
`
`( Ack,
`
`
`
`CPE HAS
`VERIFED
`IP ADDRESS
`FOR NH
`
`)"
`
`
`
`
`
`CMTS
`UPDATES
`TABLES
`
`316
`
`318
`
`Page 25 of 41
`
`

`

`1
`METHOD AND SYSTEM FOR ADDRESSING
`NETWORK HOST INTERFACES FROMA
`CABLE MODEM USING DHCP
`
`FIELD OF INVENTION
`The present invention relates to communications in com
`puter networks. More Specifically, it relates to a method and
`System for addressing network host interfaces from a cable
`modem.
`
`1O
`
`BACKGROUND OF THE INVENTION
`Cable television networks such as those provided by
`Comcast Cable Communications, Inc., of Philadelphia, Pa.,
`Cox Communications of Atlanta Ga., Tele-Communications,
`Inc., of Englewood Colo., Time-Warner Cable, of Marietta
`Ga., Continental Cablevision, Inc., of Boston Mass., and
`others provide cable television Services to a large number of
`Subscribers over a large geographical area. The cable tele
`Vision networks typically are interconnected by cables Such
`as coaxial cables or a Hybrid Fiber/Coaxial (“HFC’) cable
`system which have data rates of about 10 Mega-bits-per
`second (“Mbps”) to 30+ Mbps.
`The Internet, a world-wide-network of interconnected
`computers, provides multi-media content including audio,
`Video, graphics and text that requires a large bandwidth for
`downloading and viewing. Most Internet Service Providers
`(“ISPs') allow customers to connect to the Internet via a
`serial telephone line from a Public Switched Telephone
`Network (“PSTN”) at data rates including 14,400 bps,
`28,800 bps, 33,600 bps, 56,000 bps and others that are much
`slower than the about 10 Mbps to 30+ Mbps available on a
`coxial cable or HFC cable system on a cable television
`network.
`With the explosive growth of the Internet, many custom
`ers have desired to use the larger bandwidth of a cable
`television network to connect to the Internet and other
`computer networks. Cable modems, Such as those provided
`by 3Com Corporation of Santa Clara, Calif., U.S. Robotics
`Corporation of Skokie, Ill., and others offer customers
`higher-speed connectivity to the Internet, an intranet, Local
`Area Networks (“LANs”) and other computer networks via
`cable television networks. These cable modems currently
`Support a data connection to the Internet and other computer
`networks via a cable television network with a "down
`stream” data rate of 30+ Mbps, which is a much larger data
`rate than can be Supported by Serial telephone line used over
`a modem.
`However, most cable television networks provide only
`uni-directional cable Systems, Supporting only a "down
`Stream” data path. A downstream data path is the flow of data
`from a cable system “headend” to a customer. A cable
`System headend is a central location in the cable television
`network that is responsible for Sending cable Signals in the
`downstream direction. A return data path via a telephone
`network, such as a Public Switched Telephone Network
`provided by AT&T and others, (i.e., “telephony return') is
`typically used for an "upstream” data path. An upstream data
`path is the flow of data from the customer back to the cable
`System headend. A cable television System with an upstream
`connection to a telephony network is called a “data-Over
`cable system with telephony return.”
`An exemplary data-over-cable System with telephony
`return includes a cable modem termination System, a cable
`television network, a public Switched telephone network, a
`telephony remote access concentrator, a cable modem, cus
`tomer premise equipment (e.g., a customer computer) and a
`
`15
`
`25
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`6,058,421
`
`2
`data network (e.g., the Internet). The cable modem termi
`nation System and the telephony remote access concentrator
`together are called a “telephony return termination System.”
`The cable modem termination System receives data pack
`ets from the data network and transmits them downstream
`via the cable television network to a cable modem attached
`to the customer premise equipment. The customer premise
`equipment Sends responses data packets to the cable modem,
`which sends response data packets upstream via the public
`Switched telephone network to the telephony remote access
`concentrator, which Sends the response data packets back to
`the appropriate host on the data network. The data-over
`cable System with telephony return provides transparent
`Internet Protocol ("IP") data traffic between customer
`premise equipment, a cable modem and the data network
`(e.g., the Internet or an intranet). AS is known in the art, IP
`is a routing protocol designed to route traffic within a
`network or between networks.
`When a cable modem used in the data-over-cable system
`with telephony return is initialized, it will make a connection
`to both the cable modem termination system via the cable
`network and to the telephony remote access concentrator via
`the public Switched telephone network. If the cable modem
`is using telephony return, it will acquire telephony connec
`tion parameters on a downstream connection from the cable
`modem termination system and establish a Point-to-Point
`Protocol (“PPP) connection to connect an upstream channel
`to the telephony remote acceSS concentrator. AS is known in
`the art, PPP is used to encapsulate datagrams over a Serial
`communications link. After a PPP connection is established,
`the cable modem negotiates a telephony IP address with the
`telephony remote acceSS concentrator. The telephony IP
`address allows the customer premise equipment to Send IP
`data packets upstream to the telephony remote acceSS con
`centrator via the public Switched telephone network to the
`data network.
`The cable modem also needs to make an IP connection to
`the cable modem termination system so that IP data received
`on the cable modem termination System from the data
`network can be forwarded downstream to the customer
`premise equipment via the cable network and the cable
`modem. In one embodiment of the present invention, the
`cable modem establishes an IP address with the cable
`modem termination System through the telephony remote
`acceSS concentrator using a Dynamic Host Configuration
`Protocol (“DHCP”). As is known in the art, DHCP provides
`configuration parameters for network host interfaces (e.g., IP
`interfaces) to network hosts.
`There are several problems with using DHCP to configure
`network host interfaces Such as IP interfaces available on the
`cable modem termination system. DHCP was not originally
`intended for use in configuring a System like the data-over
`cable System with telephony return. In the data-Over-cable
`System with telephony return, a cable modem desires to
`establish an IP connection with the data network with an IP
`interface available on the cable modem termination System.
`However, the cable modem only has a downstream connec
`tion from the cable modem termination system. The cable
`modem has an upstream connection to the telephony remote
`acceSS concentrator via the public Switched telephone net
`work. However, the telephony remote acceSS concentrator
`does not have any DHCP servers for receiving DHCP
`requests. The cable modem termination system has DHCP
`servers for receiving DHCP requests for network host
`interfaces, but it cannot be accessed directly by a cable
`modem in a data-Over-cable System with telephony return.
`The cable modem has to create a DHCP-discover
`message, Send it to the telephony remote acceSS concentrator
`
`Page 26 of 41
`
`

`

`6,058,421
`
`3
`via the public Switched telephone network and have the
`telephony remote acceSS concentrator forward the message
`to a DHCP server associated with network host interfaces
`available on the cable modem termination System. However,
`there is currently no way to accomplish the connection
`scenario with DHCP since the telephony remote access
`concentrator has no mechanism to forward DHCP-discover
`messages to DHCP servers associated with the cable modem
`termination system. The DHCP servers are not directly
`addressable by a cable modem Since the cable modem has
`only a downstream connection from the cable modem ter
`mination System via the cable network.
`AS a result, the cable modem cannot create a transparent
`IP data path using DHCP to receive IP data packets from the
`data network on a downstream data channel on the cable
`network from a network host interface available on the cable
`modem termination System and Send IP data packet
`responses back to the data network upstream though the
`telephony remote access concentrator via the public
`Switched telephone System.
`There have been proposed extensions to the DHCP pro
`tocol to solve the problems associated with using DHCP to
`configure data-over-cable Systems with telephony return.
`However, the proposed extensions to DHCP require changes
`to the DHCP protocol specifically for the special case of a
`data-over-cable System with telephony return. This may not
`be desirable for the DHCP protocol, which was originally
`designed for other purposes. In addition, DHCP protocol
`extensions would require upgrading all existing DHCP Serv
`erS on a large number of third party platforms. This would
`take a considerable amount of time and be very expensive to
`existing network owners. It is desirable to use the existing
`DHCP protocol to allow a transparent IP connection for a
`cable modem to/from a data network using a data-Over-cable
`System with telephony return.
`
`SUMMARY OF THE INVENTION
`
`In accordance with an illustrative embodiment of the
`present invention, the problems associated with using the
`DHCP protocol to configure a data-over-cable system with
`telephony return are addressed. A method and System for
`addressing network interface hosts from a cable modem in
`a data-Over-cable System with telephony return is provided.
`The method and system include a first network device that
`is connected to a first network with a downstream connec
`tion of a first connection type, and connected to a Second
`network with an upstream connection of a Second connec
`tion type. The first and Second networks are connected to a
`third network with a third connection type. In one embodi
`ment of the present invention, the first network device is a
`cable modem, the first network is a cable television network,
`the Second network is a public Switched telephone network
`and the third network is a data network (e.g., the Internet or
`an intranet). The downstream connection is a cable televi
`Sion connection, the upstream connection is a Serial line
`connection, and the third connection is an IP connection.
`The method includes receiving a Selection input on a first
`network device from the first network over the downstream
`connection. The Selection input includes a first connection
`address allowing the first network device to communicate
`with the first network via the upstream connection to the
`Second network. A first message of a first type is created on
`the first network device having the first connection address
`from the Selection input in a first message field. The first
`message is used to request a network host interface address
`on the first network for accepting data on the first network
`
`4
`from the third network for the first network device. The first
`connection address allows the first network device to have
`the first message with the first message type forwarded to
`network host interfaces on the first network via the upstream
`connection to the Second network.
`The first network device sends the first message over the
`upstream connection to the Second network. The Second
`network uses the first message field in the first message to
`forward the first message to one or more network host
`interfaces available on first network. Network host inter
`faces available on the first network that can provide the