Cisco DNCS System Release 2.7 3.7 4.2 设计指南
1-30
Introducing DOCSIS
4000358 Rev B
DHCT Response to System Interruptions,
Continued
If the DHCT does not receive DBDS broadcast data, new IPPV event purchases will
only succeed if the appropriate GBAMs were cached by the DHCT prior to the
DOCSIS channel interruption. RPPV events, OOB SI updates, SAM updates and IPG
updates will not function without DBDS broadcast data. Interactive applications and
new VOD event purchases will not function.
Loss of DBDS Broadcast Data On a DOCSIS Channel
A DHCT operating in DOCSIS mode responds to the loss of DBDS broadcast data in
Loss of DBDS Broadcast Data On a DOCSIS Channel
A DHCT operating in DOCSIS mode responds to the loss of DBDS broadcast data in
the following ways:
•
•
The DHCT maintains its interactive DOCSIS connection without interruption.
•
The DHCT scans for a downstream DAVIC out-of-band QPSK signal, and uses the
DAVIC channel if present to receive DBDS broadcast data.
•
The DHCT does not attempt to scan the DOCSIS frequency band for a different
DSG-enabled signal.
•
The DHCT does not attempt to establish an interactive DAVIC connection.
•
The DHCT maintains audiovisual services and does not disrupt these services as
DBDS broadcast data is recovered and an interactive connection is restored.
Loss of DBDS Broadcast Data While the DHCT Boots
A DHCT responds to the loss of DBDS broadcast data while booting in the following
A DHCT responds to the loss of DBDS broadcast data while booting in the following
ways:
•
•
While booting, if a DHCT finds DBDS broadcast data on a DAVIC QPSK signal
but not on any DOCSIS channel, and the DCM message indicates that the DOCSIS
mode is to be used, the DHCT will establish an interactive DOCSIS connection.
The DHCT will operate in Mixed DOCSIS/DAVIC Mode until it is rebooted.
•
While booting, if the DHCT cannot find DBDS broadcast data on a DOCSIS signal
or on a DAVIC QPSK signal, it will not establish any interactive connection. The
DHCT will continue to search for DBDS broadcast data on either the DAVIC or
DOCSIS channel until it is found. IP data-forwarding services for interactive
DHCT applications and for external CPE will be unavailable until DBDS broadcast
data is again available.