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Overview
In voice communications, traffic volume is regulated using the Call Admission Control (CAC) feature. CAC prevents over subscription of a managed network by monitoring packets entering the network in the call setup phase. CAC averts voice traffic congestion by ensuring that there is enough bandwidth for authorized flows.
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Dynamic peers are created with the registrations. The lifespan of dynamic peers are associated with their registration period. As soon as registration expires dynamic peers are deleted from the peer table. Similar to static peers, dynamic peers are also restricted to work under ceiling limit of bandwidth.
supports bandwidth Call Admission Control (CAC) per supported media type1 by limiting video streams to specified bandwidth limits in order to provide a level of protection from video calls consuming call bandwidth otherwise needed for audio calls. This protection is implemented on by setting video thresholds (bandwidthVideoThreshold) to specific limits at the zone, trunk group, endpoint and shared CAC levels. The thresholds are a percentage of
the total bandwidth limit such that any traffic above this level is reserved for audio-only calls. This video threshold limit behaves the same for emergency as well as non-emergency calls. Any video calls above the video threshold limit are dropped to allow audio calls to use this bandwidth.| Note |
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If the routing Packet Service Profile is configured with “Audio Only If Video Is Prevented” flag enabled (the default value), reduces the session to audio-only calls if bandwidthVideoThreshold limit is reached. |
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NOTE 1: There is no bandwidth CAC for MSRP, data channels, FECC, and BFCP streams. |
SBC implements CAC at the application layer using Zone CAC, SIP Trunk Group CAC and SIP CAC Profile. For each of these CACs, the following configuration rules apply:
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Zone CAC applies call, media bandwidth, and registration controls to a set of peers in a zone. Since a zone typically correlates to a single customer, this is equivalent to applying controls to that customer.
A Zone can be viewed as representing a customer. The SBC The
supports CAC for calls, media bandwidth, and registrations at the zone level.
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If the emergencyOversubscription percentage is non-zero, then emergency calls are given preference over normal calls when restricting call rates. For example, if the allowed rate is 10 cps, and the SBC the
is presented with a call rate of 10 cps of normal calls and 5 cps of emergency calls, then on average
the SBC the will allow 5 cps of emergency calls and just 5 cps of normal calls.
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