Networking Requirements
To ensure sufficient bandwidth for established voice calls and for users with a high priority to access at any time, configure the Call Admission Control (CAC) function on the AR.
CAC uses the SIP protocol to control the codec type carried by packets and remaining voice bandwidth, and determines whether to allow new calls on the AR. On a live network, the total voice bandwidth on the AR is determined by the minimal DSLM upstream/downstream activation rate. In principle, the total voice bandwidth on the AR does not exceed the minimal value. Otherwise, the voice quality of established calls may be compromised. After the CAC function is configured on the AR and a new call is made, the AR senses the status of the voice user, and allocates bandwidth from the remaining bandwidth for the current user. If the bandwidth is insufficient, the call is rejected. By doing so, the CAC function ensures voice quality of established calls.
Figure 1-1 CAC networking
Procedure
Step 1 Router configuration
#
acl number 3000
rule 5 permit ip source 192.168.1.0 0.0.0.255
//Configure the NAT policy for voice users on a private network.
#
NAT cac enable bandwidth 100 //Enable the CAC function.
#
interface Ethernet0/0/0
undo portswitch
ip address 172.16.1.2 255.255.255.0
NAT outbound 3000 //Configure NAT outbond
on the WAN side, and perform source NAT for private network users.
#
interface Ethernet0/0/1
port link-type access
port default vlan 192
#
interface Vlanif192
ip address 192.168.1.1 255.255.255.0
#
ip route-static 1.1.1.0 255.255.255.0 172.16.1.1
//Configure default routing to the SBC.
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