h can be used later as a reference in case there is any variation from normal performance after the software upgrade. The new software is downloaded into the equipment's hard disk, after which the process of new package creation is started. Firstly, files are copied that do not require conversion and the remaining system files are converted to suit the new package delivery. The new package is created but only activated at midnight, SO that traffic disruption affects the minimal traffic volume and if any technical faults happen they can restore the situation before the traffic picks up in normal working hours. The second shift starts after midnight, when the crucial cutover takes place causing a network outage for a few minutes, depending on the network element. This outage lasts for as long as it takes to load the new software into all the critical units and for the interfaces with the connected elements to come up in their respective working condition. Once everything is back in normal working order, the system is checked for any abnormal behaviour or any alarms being generated due to some unit or element failure caused by the new software. Thereafter all normal processes are observed as they were performed before, like alarm uploading to the operation and maintenance centre, measurements being taken and reported, statistics generation, working of links and interfaces. Then normal subscriber activities, like calls, messages, downloads, etc., are done to ensure normal functioning of the network. Once all the units of the network element have come up with the new software then all the basic tests have been done in order to verify that the equipment is in correct working order and its performance is stable with respect to the rest of the network. The breakdown of a normal software upgrade process is shown in Figure A.11. Network Maintenance In order to maintain normal and stable running of any network, adequate equipment care needs to be taken and regular performance and health checks need to be done. This can be d