Summary
Network management starts even before VoIP deployment. Prior to VoIP deployment the transport network is assess for its resiliency, high availability, performance and capacity. This process involves analysis of the IP network done by the tools, traffic engineering for capacity planning, verification using voice traffic simulation, and network transmission loss planning to ensure voice quality will be preserved throughout the IP network and its interfaces with public land and mobile network (PLMN) through TDM voice gateways.
Voice quality metrics including MOS/K-factor, PSQM, and PESQ will be monitored for proactive management on the call processing entities. All the contributing factors including latency, jitter, packet drop and signal levels should be analyzed on the network devices through which media traffic traverses. This is only possible if the network management systems (NMS)are accurately and completely able to discover all the devices in the network using seed devices, CDP, routing tables, arp cache analysis, or ping sweeps. All of the managed devices must be synchronized with a common time source using Network Time Protocol (NTP) so information from individual devices can be correlated accurately in the time context.
Network management systems can employ various methods including SNMP polling, subscribing to alarms/traps, and Syslog analysis to track key performance indicators (KPI’s). All of this information is correlated and tracked on customized dash boards to provide meaningful metrics in the proper context.
In essence VoIP guideline include transmitting voice the fastest way possible by keeping the delay less than 150 ms. Excessive delay will worsen the echo and cause awkward conversations. VoIP packets must be transmitted as a steady smooth stream to minimize jitter without dropping any packets. This will require end–to-end QoS implementation covering all the network layers.
The proactive management approach may still have some fallout which will be covered by trouble ticketing systems. These TT systems should be tied with NMS so the problems could be resolved quickly by virtue of correlation with underlying cause(s).
