port directory of FE. This information is important because there may be preferences as to which FE server the client fails-over. The BE server maintains information about the FE server to which any given client is connected and also maintains a list of other FE servers. When the list changes, the BE notifies all clients of the change. There are two ways in which com- munication between an FE server and client may be disrupted, and they are dealt with in different ways: When a client is disconnected from the FE server, the BE notifies the client that it has been disconnected and provides it with a list of the other FEs which it maintains. When an FE server fails, the clients to which it is connected detects a communi- cation failure. The client is automatically connected to some other FE server from the list whose mode of communication with the client is the same as that of the now-failed FE server. 11.2.11.1 Scheduling Services Scheduling services allow automated network configuration processes to be sched- uled. Scheduling allows services to be implemented at a desired time without OSS for Telecom Networks manual intervention. Of course, this can improve the efficiency of operations. Periodic scheduling invokes a particular task periodically, such as every 10 seconds. In other cases, the time periods might be much longer. For example, subscribers in the UK and other football/soccer fans around the world might sign up for a service that informs of the scoring of goals in real-time. During the normal football season, this would require the reservation of bandwidth at particular times on a weekly basis. During the World Cup, the period would be for particular hours of each day.43 11.2.11.2 Logging Services Logging is used to keep track of the actions taking place in the server. When the server is started, any action occurring in the server, such as initialization, port on which the server was started, list of processes started or error messages, are recorded or "logged" in log files. The default logging parameters