Cisco Headend System Release 2.7 Design Guide
Software Components of an SDV System
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Mini-Carousel
The SDV server generates a separate file for each service group and repeatedly
transmits the file in "carousel" fashion to all the SDV clients in each service group.
Each "mini-carousel" contains a list of programs already being transmitted to its
service group, including the tuning parameters required to access them. This serves
as a redundant tuning mechanism for the SDV client in order to enhance the
reliability of channel change operation. For example, in cases of reverse path failure,
the mini-carousel would provide an alternate means of tuning to established
programs.
transmits the file in "carousel" fashion to all the SDV clients in each service group.
Each "mini-carousel" contains a list of programs already being transmitted to its
service group, including the tuning parameters required to access them. This serves
as a redundant tuning mechanism for the SDV client in order to enhance the
reliability of channel change operation. For example, in cases of reverse path failure,
the mini-carousel would provide an alternate means of tuning to established
programs.
USRM Software (Optional)
The USRM software enables systems to distribute and scale the real-time session and
resource management functions of the DNCS. It allows applications to access the
network and then deliver the requested content to edge devices under its control.
The USRM can be configured to operate in one of two possible modes:
resource management functions of the DNCS. It allows applications to access the
network and then deliver the requested content to edge devices under its control.
The USRM can be configured to operate in one of two possible modes:
Supervised mode – The USRM is provisioned using the DNCS (or another SNMP
provisioner). When the USRM is started, the USRM software requests provisioning
from the DNCS before the USRM begins to provide services.
provisioner). When the USRM is started, the USRM software requests provisioning
from the DNCS before the USRM begins to provide services.
When the USRM boots, it issues an SNMP trap to the DNCS requesting
provisioning. The DNCS uses SNMP to download to the USRM its configuration
parameters that were set for it using the DNCS. This is referred to as solicited
provisioning.
provisioning. The DNCS uses SNMP to download to the USRM its configuration
parameters that were set for it using the DNCS. This is referred to as solicited
provisioning.
In addition, unsolicited provisioning occurs when the USRM configuration
parameters are pushed from the DNCS to the USRM whenever a change in the
USRM configuration is entered into the DNCS.
parameters are pushed from the DNCS to the USRM whenever a change in the
USRM configuration is entered into the DNCS.
Unsupervised mode – Also known as standalone mode. The USRM is provisioned
and configured directly using its web browser interface. No SNMP provisioner is
available or used to provide provisioning and startup state.
and configured directly using its web browser interface. No SNMP provisioner is
available or used to provide provisioning and startup state.
GQAM Software
Session-based operation (as opposed to table-based mapping of input streams to
outputs) is required for SDV. The GQAM has always been a session-based
modulator. The GQAM software, however, has been extensively upgraded to
support SDV.
outputs) is required for SDV. The GQAM has always been a session-based
modulator. The GQAM software, however, has been extensively upgraded to
support SDV.
Besides support of other standard IP protocols through the GbE port (for example,
ARP and ICMP), the GQAM software now supports Internet Group Management
Protocol version 3 (IGMPv3). This enables the GQAM to support standard joining
and leaving of multicast groups as well as to respond to queries regarding group
membership in multicast groups. Additionally, the GQAM now supports new
standard messaging interfaces required for SDV.
ARP and ICMP), the GQAM software now supports Internet Group Management
Protocol version 3 (IGMPv3). This enables the GQAM to support standard joining
and leaving of multicast groups as well as to respond to queries regarding group
membership in multicast groups. Additionally, the GQAM now supports new
standard messaging interfaces required for SDV.