Alcatel-Lucent OmniAccess 700, Cli Configuration Manual

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Call Admission Controller
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CLI Configuration Guide
Alcatel-Lucent
CAC O
VERVIEW
In a typical deployment, QoS provides priority to certain type of traffic including
voice. But to have effective voice communication, QoS alone may not be
sufficient.
Consider an outgoing WAN interface that is capable of providing bandwidth for
two voice calls and a third call comes in. Instead of rejecting the request, if
allowed, it might affect all the existing as well as the new calls, with poor voice
quality (like jitter) and delay would be observed everywhere. Few reasons for the
poor voice quality can be network congestion and delay or overloaded gateways.
CAC avoids network congestion by dropping connection requests that cannot be
serviced with the requested QoS parameters.
Since voice is very stringent on its QoS requirement and sensitive to latency and
packet loss, CAC is required for such traffic. CAC is therefore a deterministic and
informed decision that is made before a voice call is established. It is based on the
availability of the network resources that are required to provide suitable QoS for
the new call
.
There are different mechanisms, which can be used to provide CAC functionality.
•
Measurement based CAC
•
Resource based CAC
M
EASUREMENT
B
ASED
CAC
This mechanism probes the network to find out the delay and congestion even
before the call is established. Based on the result, decision will be made whether
to allow the call or not.
R
ESOURCE
B
ASED
CAC
There are multiple resources, which can contribute to the decision for allowing/
controlling new calls in Resource Based CAC. CPU, Memory, Link Bandwidth,
etc., can be used to calculate the resource availability.
Resources like CPU, memory availability can be used to make decision but
cannot reserve. Link bandwidth can be reserved for specific calls and released
when the call ends.