Chapter 26: Connection Admission Control
STANDARD Revision 1.0
C4® CMTS Release 8.3 User Guide
© 2016 ARRIS Enterprises LLC. All Rights Reserved.
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General CAC Description
CAC is a C4/c CMTS feature used to determine if adequate resources (specifically, channel bandwidth) are available to
permit a new service flow to be established. The CAC feature tracks allocated bandwidth based on the minimum
throughput (MinSFRerserved) value of the service flow, and tracks the total allocated bandwidth on a new per channel
basis. This total is used to determine if the additional bandwidth for the new flow will exceed a configured threshold for a
given channel. Separate "buckets" are used to track the bandwidth allocated for normal voice, emergency voice, and
multicast.
Note: The Call Management Server (CMS) or Policy Server detect and signal the priority of the call (normal versus
emergency) to the C4/c CMTS.
Reserved Bandwidth
Bandwidth resources can be reserved exclusively for both emergency voice calls and normal voice calls.
Reserved percentages are set using CLI commands.
Rules that apply to reserved bandwidth implementation include:
Multicast flows may not use bandwidth that was reserved for normal or emergency VoIP calls
Bandwidth that is used for a normal call reserved may be preempted by an emergency VoIP call (up to the maximum
emergency call bandwidth threshold) if the system is configured accordingly.
PacketCable CAC Description
PacketCable (or voice) CAC thresholds for upstream and downstream channels for allowed-normal-voice should be
configured so that adequate bandwidth is available for channel management and modem registration purposes. The value
for allowed-emergency-voice should have at least enough bandwidth to do basic channel management of creating and
destroying dynamic service flows.