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Frame Relay for Voice over IP Configuration Example
Note Lowering the MTU size affects data throughput speed.
•CIR equal to line
—Use IP Precedence to prioritize voice traffic.
—Use compressed RTP to minimize voice packet header size.
•Traffic
—Use compressed RTP, reduced MTU size, and adaptive traffic shaping based on BECN to hold data rate to CIR.
—Use generic traffic shaping to obtain a low interpacket wait time. For example, set Bc to 4000 to obtain an
Note We recommend FRF.12 fragmentation setup rules for Voice over IP connections over Frame Relay. FRF.12 was implemented in the Cisco IOS Release 12.0(4)T. For more information, refer to the Cisco IOS Release 12.0(4)T “Voice over Frame Relay using FRF.11 and FRF.12” feature module.
Frame Relay for Voice over IP Configuration Example
For Frame Relay, it is customary to configure a main interface and several subinterfaces, one subinterface per PVC. The following example configures a Frame Relay main interface and a subinterface so that voice and data traffic can be successfully transported:
interface Serial0/0 ip mtu 300
no ip address encapsulation
no ip
interface Serial0/0.1
ip address 40.0.0.7 255.0.0.0 no ip
no ip
In this configuration example, the main interface has been configured as follows:
•MTU size of IP packets is 300 bytes.
•No IP address is associated with this serial interface. The IP address must be assigned for the subinterface.
•Encapsulation method is Frame Relay.
Configuring Voice over IP for the Cisco 3600 Series