Telecommunications traffic engineering, teletraffic engineering, or traffic engineering is the application of traffic engineering theory to telecommunications. Teletraffic engineers use their knowledge of statistics including queuing theory, the nature of traffic, their practical models, their measurements and simulations to make predictions and to plan telecommunication networks such as a telephone network or the Internet. These tools and knowledge help provide reliable service at lower cost.
The crucial observation in traffic engineering is that in large systems the law of large numbers can be used to make the aggregate properties of a system over a long period of time much more predictable than the behavior of individual parts of the system. One of the many advantages of the NAMS Firefly CS is our ability to store years of data from your network.
Public Switch Telephone Networks
The measurement of traffic in a public switched telephone network (PSTN) allows network operators to determine and maintain the quality of service (QoS) and in particular the grade of service (GoS) that they promise their subscribers. The performance of a network depends on whether all origin-destination pairs are receiving a satisfactory service.
A very important component in PSTNs is the SS7 network used to route signalling traffic. As a supporting network, it carries all the signalling messages necessary to set up, break down or provide extra services. The signalling enables the PSTN to control the manner in which traffic is routed from one location to another.
Transmission and switching of calls is performed using the principle of time-division multiplexing (TDM). TDM allows multiple calls to be transmitted along the same physical path, reducing the cost of infrastructure.
Voice over IP Networks
The growing popularity of Voice over IP (VoIP) is evident on the residential, enterprise, and carrier networks. The traditional IP-based networks are designed for data traffic, and there is no engineering consideration for voice traffic which is sensitive to packet delay and loss. To meet the new challenges of network convergence of both voice and data services on the same network, traffic engineering is important to network design as well as to the continual operation of the services. Among the various available traffic engineering models, the Erlang-B model has been widely used to engineer the voice traffic of circuit-switched networks for many years. The purpose of the Erlang-B model is to calculate the resources (outgoing trunks) based on the Grade of Service (GoS) and traffic intensity. The limiting resource in this network is the number of trunks between switches. In packet-switched networks, there are no circuits or trunks. These networks accept any incoming packets. If the arrival rate of incoming packets is higher than the service rate of the network, constrained by network devices or outgoing links, packets will be buffered for later delivery. The effect of packet buffering is longer delay. If the buffer is full, new packets are discarded, which result in packet loss.
When packets are lost, an upper layer protocol between the sender and the receiver (not in the intermediate node) may retransmit the packet, which would result in even longer delay. Of course, some protocols, such as UDP, may ignore the lost packets and take no actions. This operation of packet-switching is not appropriate for voice communication which is sensitive to delay and packet loss.
How we can help
The NAMS Firefly CS has the ability to perform complex calculations based upon the data we receive from your switching network. The NAMS Firefly CS has the ability to collect information from your switch Operational Measurements, SS7 traffic, SIP traffic and/or AMA tickets, so traffic engineering can be performed from any of these sources. Scheduled reports can keep you up to date on your switches daily performance, and alert you to situations where a route is under-engineered. Bandwidth reports by IP address can illuminate issues on SIP routes. MetaSwitch customers can also set up alerts on items such as jitter, packet loss, and more.
If you can’t see what’s happening within your switching network, there may be several cases of customers experiencing poor quality of service. The NAMS Firefly CS can illuminate these issues for you, and give you the data to resolve the situation.