Design Considerations

In most scenarios, voice and data are sent together on the same WAN connection. Sending voice along with data over a WAN network requires additional planning and configuration. This book focuses on gateways, but you must plan for voice flow throughout your network and configure every network device appropriately.

Be sure to consider the following areas when designing a voice-enabled WAN:

• Bandwidth Estimate the number of calls you anticipate over the WAN, plus the amount of data traffic, and ensure that you have enough bandwidth. For more information on bandwidth planning, see Chapter 16, "Deploying Gatekeepers."
• Call admission control (CAC) If the gateway sends out more calls than the WAN can handle, the quality of all calls suffers. Chapter 11, "Influencing Path Selection," covers CAC.
• QoS If voice will share the WAN link with data, you should protect voice (and video) from data. The next section of this chapter covers QoS.
• Security Consider how secure your network must be and what devices the voice traffic will traverse. For more information on security, see the "Security" section later in this chapter.

Quality of Service