Mitel SX-2000, sx-200 manual SX-200 General Information Guide, Revision a 50003510

SX-200 General Information Guide

customers with high traffic could give users enough speech paths by installing large PBXs with more ports and thus more speech paths.

The introduction of digital systems replaced speech paths with call connections and channels. Using time division multiplexing, a single piece of wire could now carry up to 32 simultaneous conversations. The result was a system that was physically smaller but able to carry many more calls. These systems were often referred to as non-blocking, implying that all users of the system could be placing calls at the same time, and a lack of system resources would not prevent any of these calls from being completed.

To improve system efficiency, PBXs are normally engineered so callers are competing for limited system resources such as trunks. This contention allows the system to make better use of trunks by scheduling callers on each trunk. Most users are unaffected by this as a higher percentage of traffic in a system is traditionally with inside parties. Key Systems force users to manually select outgoing lines as most of their traffic is external calls.

Another factor which must be considered is traffic peaks. Although most system analysis is done using average traffic, maximum peaks must also be identified. If traffic in any period exceeds these specified maximums, system performance will likely degrade, and over-competition for resources may result. Once traffic drops below this peak, the system will provide normal performance. When purchasing a system, ratings for system peak capacities should be determined for your configuration rather than using the average figures for the product line.

Here are some facts about the SX-200 EL/ML system relating to traffic.

(a)The systems provide for at least 200 simultaneous call connections. This means that 200 stations can talk to 200 other stations or trunks before call connections could create blocking.

(b)In peripheral digital bays the concentration of ports to channels is 96:90. This means that if only 90 devices are installed in a digital bay there is no possibility of blocking on channels. Adding Datasets could increase the number of devices to the point where some blocking for channels could occur. Statistically, however, there should be limited performance impact.

(c)To withstand peaks in traffic, Mitel Networks rates its switches according to line size using the very heavy traffic patterns stipulated in ATT0048.

Mitel Networks also tests the systems to ensure that they can withstand twice the traffic specified for the line-size of the switch. This is to ensure that peak traffic will not impact system performance under normal conditions.

The SX-200 EL/ML system also contains a traffic measurement package to help monitor actual traffic patterns. This traffic information must be considered when additional lines and trunks are added to an existing system. For example, information on dial tone delays may indicate a need for additional receiver modules. Console pegs can indicate the need for additional console positions. Trunk usage reports can indicate the need for additional trunks.

Use the traffic report figures as guidelines. Specific departments or trunks may not follow the averages of the rest of the system. This should be understood and analyzed to ensure that your system can meet the needs of all users.

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