S 6.18 Provision of redundant lines
Initiation responsibility: Head of IT, Persons responsible for individual applications
Implementation responsibility: Building Services, Administrator
Redundant wiring means that additional connections are provided between appropriate points in the network in addition to the lines used for normal operation. These should be routed over an alternate tray. This allows for switching to a redundant connection in the event of malfunctions. The connections can be switched manually or automatically. The automatic switchover must be indicated at a location triggering the repair of the faulty normal line.
The redundant lines must be tested at reasonable intervals for proper operation by actually operating them. The number of and the basic need for redundant lines, as well as the test intervals, depend directly on the availability requirements placed on the network. Similarly, the amount of time required to activate the redundant line and to repair the normal line must also be taken into account. However, it is crucial to know whether the lines are operated by the public sector (e.g. Telekom) or by the private sector.
- The user has no influence on the protection of public sector lines. The public network usually has a sufficient number of redundant lines available for use. In most cases, when a connection fails (regardless of whether the this is a dedicated line or a dial-up line), it will suffice to restore the connection by setting up a dial-up line. It is usually too expensive and, in most cases, not absolutely necessary to provide redundant dedicated connections.
- In a private network, the operator can significantly influence the security of lines. In most cases, though, cost considerations result in no redundant lines being installed. In private networks, however, redundant lines do not incur any additional costs other than the cost of installation.
Review questions:
- Have redundant lines been routed using a different tray?
- Is the functionality of redundant lines checked regularly?