Cisco Headend System Release 2.5 發佈版本通知
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Why Choose System Release 3.5?
4001159 Rev B
DSG: New DOCSIS Option Can Consolidate Administration of the Data
Network,
Continued
In SR 3.5, systems can continue to use unicast IP routing as necessary to support
non-DOCSIS-capable set-tops. For DOCSIS-capable set-tops, SR 3.5 introduces
support for “single-flow” multicast IP routing (multicasting). With single-flow
multicast, the network uses one group destination IP address (GDA) to deliver all
OOB data to multiple set-top populations. Administrators can create one or more
multicast streams as needed, depending on the channel map and SI configuration of
the DBDS. To support single-flow multicast, administrators create one or more
logical DOCSIS OOB bridges on the DNCS and then configure the network and cable
modem termination systems (CMTSs) to join the appropriate multicast stream as
necessary.
Note: You can use single-flow multicast with CMTS devices only. Quadrature
Note: You can use single-flow multicast with CMTS devices only. Quadrature
Phase-Shift Keying (QPSK) modulators do not support multicasting.
Multicasting conserves bandwidth on your data network. As shown in the following
Multicasting conserves bandwidth on your data network. As shown in the following
diagram, the 1.2 Mbps of bandwidth required to deliver information in the previous
unicast example is reduced to only 0.3 Mbps of bandwidth with single-flow
multicasting. The network also uses a single GDA to send the same data to multiple
groups of set-tops sharing the same channel maps and SI.