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Cisco Cable Wideband Solution Design and Implementation Guide, Release 1.0
OL-10705-02
Chapter 3 Cisco Cable Wideband Architecture
Modular CMTS
Figure 3-2
Wideband Channels and Primary Downstream Channels on a Fiber Node
A WCM on the fiber node can come online on WB1/PDC1, on WB1/PDC2, or on WB2/PDC1. On the
CMTS, WB1, WB2, PDC1, and PDC2 all are members of the same virtual interface bundle.
For information on configuring virtual bundle interfaces, see the
Cisco uBR10012 Universal Broadband
Router SIP and SPA Software Configuration Guide
.
Modular CMTS
The Cisco Cable Wideband Solution, Release 1.0, uses of a variant of the modular CMTS (M-CMTS)
architecture. With a modular CMTS architecture, the downstream PHY (physical layer) of the CMTS is
located in a separate network element: the edge QAM device. CableLabs defines the M-CMTS
architecture, which is one of the DOCSIS specifications. The M-CMTS architecture and wideband
(DOCSIS 3.0) channel bonding are closely related technology pieces.
The CableLabs specification for the M-CMTS architecture defines changes to the edge QAM device that
require it to be both DOCSIS-aware and synchronized to the DOCSIS subsystem. The Cisco Cable
Wideband Solution, Release 1.0, implementation of the M-CMTS architecture does not place these
requirements on the edge QAM device.
For a single wideband channel,
Figure 3-3
shows the M-CMTS architecture as it is used in the Cisco
Cable Wideband Solution, Release 1.0. In this example, two downstream RF channels are bonded
together into one wideband channel. The Gigabit Ethernet (GE) switch is optional.
Figure 3-3
Cisco Cable Wideband M-CMTS Architecture
In the M-CMTS architecture used for the Cisco Cable Wideband Solution, Release 1.0, traditional
CMTS functionality is divided into two network elements as follows:
190002
WB1
WB2
NB1
NB2
PDC1
PDC2
191347
WAN
WAN
uBR10012
WCMTS
Wideband SPA GE
MC5X20
cable interface
line card
Downstream
wideband
channel
Traditional DOCSIS upstream channel for
return data traffic and signaling
Traditional DOCSIS downstream channel
for MAC management and signaling messages
Regional
cable
headend
Wideband
cable modem
RF
Edge QAM
device
Downstream
wideband channel
GE
switch
Wideband SIP
Optional