Cisco Headend System Release 2.7
4001703 Rev B
Why Choose System Release 4.0?
1-3
DSG: New DOCSIS Option Can Consolidate Administration of the Data Network
Overview
In addition to the previously supported DAVIC* and mixed DAVIC/DOCSIS
®
modes,
SR 4.0 introduces the new DOCSIS* (DSG) mode for transporting all set-top data over
the DOCSIS infrastructure. While the DOCSIS option is a standard DNCS feature
included with the SR 4.0 release, this option requires the appropriate network
infrastructure to function within your system.
The DOCSIS option may be beneficial for systems wanting to consolidate data traffic
The DOCSIS option may be beneficial for systems wanting to consolidate data traffic
onto their DOCSIS network. As an added potential benefit, the DOCSIS option may
allow you to use one common out-of-band (OOB) network for multiple set-top vendors.
SR 4.0 also introduces single-flow multicast support to help you conserve bandwidth on
SR 4.0 also introduces single-flow multicast support to help you conserve bandwidth on
your data network. This section describes new network configurations and several user
interface (UI) changes associated with these new features.
*Digital Audio Visual Council; Data Over Cable Service Interface Specification
Use One IP Address and Less Bandwidth with Single-flow Multicast
Previous system releases relied solely on unicast Internet Protocol (IP) routing to deliver
Broadcast File System (BFS) and broadcast data, system information (SI), conditional
access information, and PassThru messages to different set-top populations. With
unicast IP routing, the DNCS can only send data to one destination at a time. Because
unicast traffic is destined for a unique IP address, network administrators must
configure a different OOB bridge on the DNCS for each physical OOB bridge on the
network. This configuration consumes additional network bandwidth and is inefficient.
For a given hub with unicast IP routing, the destination IP address for each OOB bridge
For a given hub with unicast IP routing, the destination IP address for each OOB bridge
is unique; however, the information carried across each bridge is almost exactly the
same. The following diagram provides a basic example of unicast IP routing in a single
hub. In this example, each OOB bridge requires 0.3 Mbps of bandwidth. The network
uses four different IP addresses and a total of 1.2 Mbps of bandwidth to deliver four
copies of the same data to multiple set-top populations.