es. tuning. 4. Higher traffic performance requirements. 4. Off-line configuration (minimum downtime). 5. Online configuration (minimum disturbance). Geographic changes, more users and new facilities tend to mean more connections and more or larger user access nodes. This nor- 40.8.10 Fault tracing mally means that the traffic requirements change i.e. the aggregate traffic levels per trunk increase. There are various tools which a networking product can supply to Higher performance can be the result of more users; higher per- aid fault tracing. At the simplest level this would be statistical counts formance end user equipment; lower transit delay requirements; or of all the frames and packets received and transmitted on each link that existing users are making more use of the network. Perfor- and trunk. With the appropriate timing information this can be mance increases can be addressed by adding links between the compiled into link utilisation and packet throughput statistics. This nodes or by raising the speed of the existing links between nodes. It 40/16 Multiplexers Packet switch exchanges Synchronous TDM 2Mbit/s circuits 64kbit/s circuits Backup Figure 40.13 A network of TDMs and PSEs is important to note that raising the link speed often means that the tends to be local, practical usage suggests that up to 90% of all data network node equipment will require upgrading. on a LAN is between local devices. 40.8.16 Adding new links The future of multiplexing When analysing the statistical information provided by a network it is important to take the historical information into account. A link running at a high utilisation may not necessarily be saturated. X.25 40.9.1 Frame relay is designed to be more efficient when a link is heavily used. The first sign that a link is becoming overloaded is when network response The speeds required by networks increases every year to cope with times become erratic. X.25 will not lose data; as the network the increase in computer processing power. Network transmission becomes bus