Avaya X330WAN manual VoIP Mode

QoS and VoIP Treatment

VoIP Mode

The incoming packets are categorized into the Rx queues as in the Data mode.

The size of each of the four Tx queues is automatically set by X330WAN as follows:

•Highest priority queue (VoIP) - Set by default to a maximum delay of

20 milliseconds, optimized for a G.729 voice CODEC (without cRTP), and implements tail-drop when overflowed. This queue is divided into two priorities, 6 and 7, which are treated differently to improve distinction between the Voice Bearer (RTP) (priority 6) and Voice Control (priority 7) packets. The two priorities are serviced in a Round-Robin one-to-one fashion, where the priority 6 (RTP) buffer is 25% the size of the priority 7 (Voice Control) buffer to reduce the delay in VoIP flow. The priority 6-7 distinction exists in Data mode as well, where the queue is divided equally between both capacities.

•The remaining queues are set using the same methods as in Data mode.

Figure 4.9 illustrates the queue and overflow concept for the Data and VoIP modes.

Figure 4.9 Default QoS Behavior

Note: You can adjust the queue length in both modes for different needs. Queue length should always be kept as small as possible, while still maintaining a flow. It is recommended to always use the default queue length, as this is the optimal calculated length. To adjust the queue length in both modes, use the queue-limitcommand.

Avaya X330WAN User’s Guide 57