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Chapter 1 The Staging Process
Download Methods
There are two methods for installing client release software to devices in a DBDS
environment:
Code Version Table (CVT) download (for newer DHCTs and CableCARD
modules).
Operating System Manager (OSM) download (for older DHCTs).
CVT Download Method
The CVT is a table that contains information about download channel and
information to map application platform software versions to specific devices.
The DNCS sends the CVT to all QAMs in the network. The QAMs then send the
CVT to the devices once every second. The DNCS also sends CVT through the
DAVIC (QPSK) or DOCSIS out-of-band forward data channel once every 10
minutes.
The CVT method is the only download method available for newer DHCTs and for
all CableCARD modules.
OSM Staging Method (for Older DHCTs Only)
In the OSM staging method, the DHCT receives System Information (SI) and a type-
specific user-to-network configuration (Unconfig) message, which includes a table of
contents (TOC) file, from the DNCS.
The DHCT reads the contents of the TOC file and compares the checksums of the
currently installed image files against the file information in the TOC file. If the
checksum of either file does not match, the DHCT installs the new software as
needed.
The OSM staging method is the only download method available for older DHCTs
and the following specific DHCT/OS combinations:
All Explorer 2000, 2010, 2100 (rev 2.0 and 2.1), and 3100 (rev 2.0 and 2.1) DHCTs
in your network must use the OSM download method.
The following Explorer DHCT revisions cannot use the CVT download method
on networks where the BFS QAM is at a harmonically related carrier (HRC)
frequency:
- Explorer 2100 rev 2.2 and 2.3 DHCTs
- Explorer 3100 rev 2.4, 2.5, and 2.6 DHCTs
Note: These DHCTs can use the CVT download method on systems using either
a standard (STD) frequency plan or an incrementally related-carrier (IRC) plan.
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