Chapter 22: Channel Bonding
STANDARD Revision 1.0
C4® CMTS Release 8.3 User Guide
© 2016 ARRIS Enterprises LLC. All Rights Reserved.
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Downstream Channel Bonding (DSCB)
The method that DOCSIS 3.0 uses to provide very high downstream throughput rates to a single CM is known as channel
bonding. Channel bonding treats multiple DOCSIS channels as one transmission medium and does not affect the physical
characteristics of any of the channels.
In the downstream direction, the C4/c CMTS distributes the packets that are destined to the same CM or group of CMs
over the multiple channels of a downstream bonding group. DOCSIS 3.0 downstream service flows may be bonded or
unbonded depending upon the type of service and the attributes that are attached to the request. Packets scheduled on
bonded downstream flows are sequenced by the CER, transmitted, and then re-sequenced by the CM so that they may be
forwarded to the destination on the other side of the CM in the order in which they were received by the CER.
With downstream channel bonding, streams of packets are distributed across the multiple downstream channels of a
Downstream Bonding Group (DBG). Downstream channel bonding has several advantages:
It allows a bonded DOCSIS 3.0 CM to receive data at a greater bit rate than it would if using a single downstream
channel
It can reduce the delay of individual downstream packets.
It can reduce the admission failures of high bandwidth flows by allowing the flow to share bandwidth across multiple
downstream channels, thus avoiding dependence on a single channel.
Downstream channel bonding increases reliability of any given data flow.
Downstream channel bonding assists in the balancing of channel utilization across the downstream channels in the
bonding group by intelligently spreading the packets down channels using an algorithm that executes per-packet
data/channel-utilization-based balancing. This is in addition to and separate from the load balancing features on the
C4/c CMTS, described in
The set of downstream channels used by the C4/c CMTS to distribute the packets of a single high-speed service flow is
called the Downstream Bonding Group.
Before DSCB can function, other items should be configured. These include correct hardware, bonding groups, MAC
domains, IP addresses, fiber nodes, and channel supervision. Supervision is explained in
Upstream to Downstream Channel
Figure 89:
Sample MAC Domain