Classifications

• • G—PHYSICS
  • G06—COMPUTING; CALCULATING OR COUNTING
  • G06F—ELECTRIC DIGITAL DATA PROCESSING
  • G06F8/00—Arrangements for software engineering
  • G06F8/60—Software deployment
  • G06F8/61—Installation
  • G06F8/64—Retargetable
• • G—PHYSICS
  • G06—COMPUTING; CALCULATING OR COUNTING
  • G06F—ELECTRIC DIGITAL DATA PROCESSING
  • G06F9/00—Arrangements for program control, e.g. control units
  • G06F9/06—Arrangements for program control, e.g. control units using stored programs, i.e. using an internal store of processing equipment to receive or retain programs
• • G—PHYSICS
  • G06—COMPUTING; CALCULATING OR COUNTING
  • G06F—ELECTRIC DIGITAL DATA PROCESSING
  • G06F15/00—Digital computers in general; Data processing equipment in general
  • G06F15/16—Combinations of two or more digital computers each having at least an arithmetic unit, a program unit and a register, e.g. for a simultaneous processing of several programs
• • G—PHYSICS
  • G06—COMPUTING; CALCULATING OR COUNTING
  • G06F—ELECTRIC DIGITAL DATA PROCESSING
  • G06F21/00—Security arrangements for protecting computers, components thereof, programs or data against unauthorised activity
  • G06F21/50—Monitoring users, programs or devices to maintain the integrity of platforms, e.g. of processors, firmware or operating systems
  • G06F21/51—Monitoring users, programs or devices to maintain the integrity of platforms, e.g. of processors, firmware or operating systems at application loading time, e.g. accepting, rejecting, starting or inhibiting executable software based on integrity or source reliability
• • G—PHYSICS
  • G06—COMPUTING; CALCULATING OR COUNTING
  • G06F—ELECTRIC DIGITAL DATA PROCESSING
  • G06F8/00—Arrangements for software engineering
  • G06F8/60—Software deployment
  • G06F8/61—Installation
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04B—TRANSMISSION
  • H04B7/00—Radio transmission systems, i.e. using radiation field
  • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
  • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
  • H04B7/08—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the receiving station
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L67/00—Network arrangements or protocols for supporting network services or applications
  • H04L67/34—Network arrangements or protocols for supporting network services or applications involving the movement of software or configuration parameters 
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L69/00—Network arrangements, protocols or services independent of the application payload and not provided for in the other groups of this subclass
  • H04L69/30—Definitions, standards or architectural aspects of layered protocol stacks
  • H04L69/32—Architecture of open systems interconnection [OSI] 7-layer type protocol stacks, e.g. the interfaces between the data link level and the physical level
  • H04L69/322—Intralayer communication protocols among peer entities or protocol data unit [PDU] definitions
  • H04L69/329—Intralayer communication protocols among peer entities or protocol data unit [PDU] definitions in the application layer [OSI layer 7]

Definitions

• the present invention is related generally to cable modems, and more specifically to a method and apparatus for ensuring that the cable modem has downloaded the correct operating software version.
• Internet access via a telephone modem is available today at speeds up to 56 Kbps.
• the telephone-based modem modulates and demodulates data signals for transmission over the voice-band based telephony network.
• a cable modem provides Internet access via the cable television system, which has a higher bandwidth and therefore can operate at higher data rates than the telephone system.
• the cable modem provides connectivity between a user's computer and the cable system headend, at which point the cable operator provides access to the Internet, via, for example a Tl transmission line.
• data transmitted from the network headend to the computer user is referred to as downstream data; data transmitted from the user to the network headend is referred to as upstream data.
• FIG 1 is a block diagram of a cable system 10 including a cable modem 20, certain features of which are well known in the prior art.
• the cable system 10 includes a headend, not shown in Figure 1, from which the cable television program signals originate and that further provides a connection to the Internet or other external network.
• a splitter 14 splits the incoming signal.
• the first output terminal provides the television program signal for display on a television 18 under control of a set top box 16.
• the second output terminal from the splitter 14 provides connectivity to the cable modem 20.
• Downstream signals from the headend are provided to an RF (radio frequency) tuner 22, which is tuned to a frequency allocated to the cable modem 20 during the modem's start-up phase.
• the downstream signal uses QAM (quadrature amplitude modulation) and therefore is demodulated in a QAM demodulator 24.
• the demodulated signal is input into a media access controller 26.
• the signal from the media access controller 26 is input to a data and control logic unit 28 that controls overall operation of the cable modem 20 and further provides data control functions.
• a computer 30 (or other communications device) is connected to the data and control logic unit 28 for receiving data sent in the downstream direction from the
• the outgoing data passes from the computer 30 through the data and control logic unit 28, through the media access controller 26, and finally is modulated by a QPSK (quadrature phase-shift keyed) or QAM modulator.
• QPSK quadrature phase-shift keyed
• QAM quadrature phase-shift keyed
• the upstream data then passes through the splitter 14 for transmission to the headend of the cable system and eventually for transmission to the Internet, World Wide Web or other external network.
• the downstream signal employs a 64/256 QAM signal capable of delivering up to 30 to 40 Mbps of data over a 6 MHz cable channel.
• Upstream data uses either QPSK or 16 QAM signaling with data rates available from 320 Kbps to 10 Mbps. Both the upstream and downstream data rates may be flexibly configured to match the data rate needs of the user. For instance, the cable modem 20 utilized by a business user could be programmed to receive and transmit at higher data rates. A residential user, on the other hand, may have a cable modem 20 configured with wider bandwidth access (and therefore a higher data rate) in the downstream direction to provide access to the external network, while limited to a lower speed for upstream data transmissions.
• upstream data from the subscribers 50 transmitted over a cable network 51 is demodulated and processed by a cable modem termination system 52 for performing data switching as it routes data from the many subscribers 50 to the Internet, World Wide Web or other external network, as shown.
• the cable modem termination system 52 receives data from the external network and provides the necessary data switching of the received downstream data to the appropriate subscriber 50 via a headend transmitter 54.
• the headend transmitter 54 also receives the program signals (via satellite downlink, terrestrial microwave or land lines) for broadcast to all the subscribers 50.
• the user data is carried over a 6 MHz channel (in Europe, the bandwidth standard is 8 MHz), which is the spectrum size allocated to a cable television channel for broadcast of program signals to all subscribers 50.
• the program signal is received by the set top box 10, while the downstream data is separately received by the cable modem 20. See Figure 1.
• the RF cable modem tuner 22 tunes out the program signal from the cable modem 20 and the set top box 16 rejects the data signal.
• the number of upstream and downstream data channels in a given cable modem system is engineered based on the service area, the number of users, the data rate allocated to each user, and the available spectrum.
• An element management system (not shown) is yet another component of the cable system 10 for configuring and managing a plurality of cable modem termination systems 52.
• the element management system is located at the cable headend 45.
• the operation of the element management system includes provisioning, day to day administration of the system, monitoring, activating alarms, and testing of the various components of the cable modem termination system 52.
• a single element management system is located at the cable system network operations center and can support many cable termination systems 52 in a wide geographic area.
• a connection is created to the cable modem termination system 52 via the cable network 51.
• This connection is made using the Internet protocol (IP) so that IP-formatted data from the external network, as received by the cable termination system 52, can be forwarded downstream to the cable modem 20 of a subscriber 50 via the cable network 51.
• IP Internet protocol
• the cable modem 20 contacts a dynamic host configuration protocol server (DHCP) using the dynamic host configuration protocol.
• DHCP dynamic host configuration protocol server
• Many such DHCP servers are available on the network and the cable modem 20 simply broadcasts to all DHCP servers. Any
• DHCP server can answer the broadcast request. From the DHCP server, the cable modem 20 obtains an IP address, other IP related operational parameters and the address of the modem configuration file.
• a configuration file address points to a trivial file transfer protocol (TFTP) server from which the cable modem 20 downloads the configuration file.
• TFTP trivial file transfer protocol
• This file includes various modem configuration settings, such as access control information, downstream and upstream channel assignments and security configuration information. Also, information in the configuration file allows the cable modem 20 to identify its operating software (based on the cable modem vendor, model number, or other designator) and the location from which the operating software can be downloaded.
• the current cable modem standard (referred to as DOCSIS, Data Over Cable Service Interface Specification) does not define an adequate process for validating the cable modem operating software, either before or after it is downloaded. Instead, the DOCSIS protocol specifies only that the download should be executed after the cable modem has gone into an encryption mode so that the download process is secure.
• the encryption feature can be turned on or off, as desired by the cable system operator, using an identified field in the configuration file.
• unusable or corrupted operating software can reside on the TFTP server from which the operating software is downloaded.
• the cable modem will not be aware that the software is unusable until the software is downloaded and the cable modem booted up. Only then will the cable modem recognize that the operating software is not usable. If the operating software is not usable, the cable modem continues to use the operating software version previously stored in memory.
• Certain memory devices for storing the operating software in the cable modem have a limited number of lifetime read/write cycles. Downloading an unusable version of the operating software wastes one of those lifetime read/write cycles.
• Figure 1 is a block diagram of the prior art components of a cable television subscriber's site
• Figure 2 is a block diagram of a prior art cable system
• Figure 3 illustrates the file header associated with the present invention
• Figure 4 illustrates the fields comprising the file header of Figure 3
• Figure 5 is a flow chart depicting the process in accordance with the present invention.
• the DOCSIS standard does not define the operating software file format. Therefore there remains a need for a method and apparatus to establish the file format and utilize information in the file to determine the applicability and validity of the operating software file at the earliest possible time during the file download process.
• an operating software file header includes operating software identification information, target hardware identification information and a checksum. Evaluation of the header information prior to downloading the operating software file and evaluation of the checksum after the download is complete, allows early determination of the applicability and the validity of the operating software file. In this way, the cable modem can avoid the lengthy download process of the prior art, which requires downloading the entire operating software file, if the file is corrupted, was tampered with, or is not the correct operating software for the cable modem.
• certain evaluations are carried out on the header or first block (74 bytes in one embodiment) of the operating software file. If the evaluations determine that the file is not valid for the cable modem, the modem will immediately abort the TFTP download session and signal an error condition to the cable modem termination system 52. In the prior art, the cable modem must download the entire operating software file before it can recognize that the operating software is not valid or is corrupted. Further, according to the present invention, the header includes a checksum for validating the entire operating software file once the download is complete. If the checksum analysis indicates that the file is not corrupted, the cable modem 20 immediately reboots and begins using the downloaded operating software file.
• the cable modem 20 In the event the checksum validation process reveals uncorrectable errors in the file, then the cable modem 20 signals an error condition to the cable modem termination system 52. Whenever an error condition is detected either by analysis of the header or the checksum, the cable modem 20 simply uses the last version of the operating software, i.e., the same operating software used during its last operating session.
• Figure 3 illustrates the fields of an operating software file 68.
• the file 68 begins with a header field 70 that will be discussed further hereinbelow.
• a decompression code field 72 sets forth parameters for decompressing the operating software code once the download is complete. In one embodiment of the present invention, neither the header field 70 nor the decompression code field 72 are in a compressed format.
• the operating software code length is set forth in a length field 74.
• the checksum for the operating software code is set forth in a checksum field 76.
• the operating software code is in a field 78. In one embodiment, the length field 74, the checksum field 76, and the code field 78 are compressed prior to transmission.
• Figure 4 shows the various components of the header field 70.
• the operating software file can be validated upon receipt and analysis of the certain fields within header 70.
• a length field 82 sets forth the length of the operating software file
• a checksum field 84 provides the checksum value for the operating software file 68.
• a target identification field 86 identifies the device type to which the operating software applies. Exemplary device types include a cable modem and a set top box. If the target identification field 86 indicates that the software is intended for a device other than a cable modem, the download is immediately aborted, and an error signal generated as discussed above.
• the software identifier field 88 identifies the nature of the operating software included within the download file. For instance, the code can be operating software, boot-up software, or a software revision table. Again, if the software identifier is incorrect, the download is immediately aborted.
• a build release field 90 identifies the version number for the operating software file.
• the version number is incorporated into the file name, which is included in the build release field 90.
• the cable modem 20 compares the file name received with the file name stored in memory (representing the last used version of the operating software). If the file names match, it is not necessary for the cable modem 20 to download the operating software.
• a vendor identification field 92 identifies the vendor and cable modem model number (or other identification number) on which the operating software will run.
• the vendor stores a vendor identification number in the cable modem memory, so that it cannot later be changed or corrupted. If the vendor identification number set forth in the vendor identification field 92 does not match the number stored in the cable modem, then the software download aborts.
• Spare bytes in the header 70 are indicated by a reference character 94. It is understood by those skilled in the art that the number of bytes occupied in the spare field 94 can vary depending upon the length of the header and the length of other header fields.
• the operating software 68 is downloaded from a TFTP server and therefore follows the TFTP protocols.
• the code is downloaded is 512 bite packets.
• the field 70, 72, 74 and 76 will generally comprise less than 512 bytes. Therefore the analysis in accordance with the present invention occurs after 512 bytes have been downloaded. This analysis proceeds sequentially from the header field 70 and its constituent fields, through the various other fields comprising the operating software file 68.
• the cable modem can independently check each field when the download for that field had been concluded.
• the header field 70 is downloaded and then the various fields associated therewith are evaluated before continuing with the download of the field 72, 74, 76 and 78.
• the download aborts and an error is generated as discussed above.
• the hardware class field 96 identifies the cable modem classes (i.e. models or groups of models) on which the operating software code in the field 78 will run. Since there are 256 bits in the hardware class field 96, 256 different hardware modem classes can be supported. The hardware identifier (which is typically eight bits long) stored in the cable modem memory is used as an index into the 256 bitmap of the hardware class field 96. If the indexed bit is set, then that hardware is supported by the operating software in the field 78. The advantage of utilizing a bitmap derives from the fact that any given operating software code can support more than one hardware class. All supported hardware classes are incorporated into the bitmap.
• the hardware identifier which is typically eight bits long
• the operating software code field 78 of Figure 3 is downloaded.
• the validity of the operating software code is determined using the checksum value in the field 76.
• the checksum value in the field 84 is utilized to analyze the entire downloaded file, including all fields set forth in Figure 3. If no problems are detected by these two checksum evaluations, the cable modem 30 reboots using the downloaded operating software.
• either one or both of the checksums 76 and 84 can also be used to correct one or more detected errors.
• Figure 5 illustrates the process of evaluating each of the various parameters set forth in Figures 3 and 4.
• the Figure 5 flow chart begins at a step 110 when the cable modem 20 powers up. Note that the analysis process illustrated in Figure 5 does not necessarily have to occur in the order shown in Figure 5.
• the target identification field 86 is compared to the device type as stored in the device, in particular a cable modem 20. Recall that software for different device types is available on the cable system 10. If the result of the step 112 is negative, the software download process is aborted at a step 114.
• processing moves to a decision step 116 where the software identification field 88 is evaluated to determine the type of software in the field 78 (see Figure 3). If the result of the decision step 116 indicates that the software is not appropriate or is not the correct software type, processing moves from the decision step 116 to the step 114 where, the download process is aborted. An affirmative response from the decision step 116 moves the process to a decision step
• the software version information (the field 90 of Figure 4) is evaluated. If the version is the same as the software version previously used by the cable modem 20, then it is unnecessary to download the software. Under those circumstances, processing moves from the decision step 118 to the abort step 114. If the decision step 118 indicates that this is a new software version, processing moves to a decision step 120 where the hardware class field 96 is evaluated. The objective of the decision step 120 is to ensure that the modem hardware class is supported by the software. If that class is not supported, the process moves from the decision step 120 to the abort step 114. If the modem hardware class is supported, the software is downloaded at a step 122. Next, error identification and correction is performed using a checksum value downloaded with the software.
• This process of error identification and correction can encompass only the downloaded software or all of the various fields associated with the header 70, using the checksum values in the checksum fields 76 and 94.
• the error identification and correction process is illustrated at a step 124. If no errors were discovered or all the errors were correctable, the result from a decision step 126 is affirmative and the cable modem is rebooted using the downloaded software (see a step 128). If the result of the decision step 126 indicates that the downloaded software includes uncorrectable errors, then, as shown at a step 130, the modem utilizes the previous version of the software, instead of the version downloaded at the step 122.

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• Engineering & Computer Science (AREA)
• Theoretical Computer Science (AREA)
• Software Systems (AREA)
• General Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Computer Hardware Design (AREA)
• Computer Security & Cryptography (AREA)
• Computer Networks & Wireless Communication (AREA)
• Signal Processing (AREA)
• Two-Way Televisions, Distribution Of Moving Picture Or The Like (AREA)
• Stored Programmes (AREA)

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• 2001
  • 2001-10-26 EP EP01992328A patent/EP1350343A4/de not_active Withdrawn
  • 2001-10-26 CA CA002429043A patent/CA2429043A1/en not_active Abandoned
  • 2001-10-26 KR KR1020037006719A patent/KR100582437B1/ko not_active IP Right Cessation
  • 2001-10-26 AU AU2002232790A patent/AU2002232790A1/en not_active Abandoned
  • 2001-10-26 WO PCT/US2001/050124 patent/WO2002041525A1/en not_active Application Discontinuation

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