Cyclic Redundancy Check On Downloaded Configuration Files - AudioCodes Mediant 800B User Manual

Note:
•
For ini file downloads, by default, parameters not included in the file are set to
defaults. To retain the current settings of these parameters, set the
SetDefaultOnINIFileProcess parameter to 0.
•
If you have configured one-time software file (.cmp) download (configured by the
ini file parameter CmpFileURL or CLI command configure system > automatic-
update > firmware), the device will only apply the file if one-time software updates
are enabled. This is disabled by default to prevent unintentional software
upgrades. To enable one-time software upgrades, set the ini file parameter
AutoUpdateCmpFile to 1 or CLI command, configure system > automatic-update >
update-firmware on.
•
If you need to update the device's software and configuration, it is recommended
to first update the software. This is because the current ("old") software (before the
upgrade) may not be compatible with the new configuration. However, if both files
are available for download on the provisioning server(s), the device first
downloads and applies the new configuration, and only then does it download and
install the new software. Therefore, this is a very important issue to take into
consideration.
•
If more than one file needs to be updated:
√
CLI Script and cmp: The device downloads and applies the CLI Script file on
the currently ("old") installed software version. It then downloads and installs
the cmp file with a reset. Therefore, the CLI Script file MUST have configuration
compatible with the "old" software version.
√
Startup Script and cmp: The device downloads both files, resets, applies the
new cmp, and then applies the configuration from the Startup Script file on the
new software version.
√
CLI Script and Startup Script: The device downloads and applies both files;
but the Startup Script file overwrites all the configuration of the CLI Script file.

51.2.9 Cyclic Redundancy Check on Downloaded Configuration Files

You can enable the device to perform cyclic redundancy checks (CRC) on downloaded
configuration files (ini) during the Automatic Update process. The CRC checks whether the
content (raw data) of the downloaded file is different to the content of the previously
downloaded file from the previous Automatic Update process. The device compares the
CRC check value (code) result with the check value of the previously downloaded file. If
the check values are identical, it indicates that the file has no new configuration settings,
and the device discards the file. If the check values are different, it indicates that the
downloaded file is different (i.e., includes updates), and the device installs the downloaded
file and applies the new configuration settings.
CRC is useful, for example, when the service provider replaces a file, on the provisioning
server, with another file whose contents are the same. When the device sends an HTTP
Get request during the Automatic Update process, the provisioning server sends the new
file to the device. This occurs as the timestamp between the previously downloaded file
and this new file is different (determined by the HTTP If-Modified-Since header in the Get
request). Therefore, the CRC feature can be used to prevent the device from installing
such files.
For enabling CRC, use the ini file parameter AUPDCheckIfIniChanged or CLI command,
configure system > automatic-update > crc-check regular. By default, CRC is disabled. For
more information on the parameter, see 'Automatic Update Parameters' on page 1068.
User's Manual
Mediant 800B Gateway & E-SBC
890 Document #: LTRT-10632