Overview of Voice over IP (VoIP)
Network Assessment
2-5
More information about SNMP and MIBs can be found in the IETF references listed in Chapter 1,
Related Documents. Appendix A of this LAN Administration Guide lists the Custom MIB, which is
also available for download in *.txt format on the Avaya support website.
Network Assessment 2
The current technology allows optimum network configurations to deliver VoIP with perceived
voice quality close to that of the Public Switched Telephone Network (PSTN). Not every network is
able to take advantage of packet voice transmissions. Some data networks have insufficient
residual capacity for even compressed voice traffic. In addition, the usual approach to developing
data networks by integrating products from many vendors makes it necessary to test the
components for compatibility with Voice over IP traffic.
It is assumed that your organization has performed a network assessment (with or without the
assistance of Avaya) before attempting to install Voice over IP, in order to have a high degree of
confidence that the existing data network has the capacity to carry voice packet traffic and is
compatible with the required technology.
A network assessment would include a determination of the following:
■A network audit to review existing equipment and evaluate its capabilities, including its ability
to meet planned voice and data needs.
■A determination of network objectives, including the dominant traffic type, choice of
technologies, and setting voice quality objectives.
The assessment should leave you confident that the implemented network will have the capacity
for the foreseen data and voice traffic, and can support H.323, DHCP, TFTP, and jitter buffers in
H.323 applications.
It is important to distinguish between compliance with the minimal VoIP standards and support for
QoS which is needed to run VoIP on your configuration.
Suggestions for Installation and Configuration 2Reliability and Performance 2
There is a cost/performance trade-off associated with Voice over IP. Greater reliability and
improved performance can be obtained through server redundancy and components with higher
bandwidth capabilities.
The reliability and performance of the traditional PBX systems have been very high. Although
much of the LAN is outside of the control of the PBX, there are several points to consider which
enhance the reliability and performance of the IP Telephone network.