IT Baseline Protection Manual - The Information Warfare Site

Safeguard Catalogue - Communications Remarks
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S 6.18 Provision of redundant lines
Initiation responsibility: Head of IT Section; staff responsible for the
individual IT applications
Implementation responsibility: Head of Site/Bldg Technical Service;
administrator
Redundant wiring means that, apart from the lines used for normal operation,
additional lines are provided between appropriate points in the network. Such
lines should be run over an alternate route. This will make it possible to switch
to a redundant line in case of malfunction. Such switching can be effected
automatically or manually. Automatic switching must be indicated to a unit
which will arrange for fault clearing on the normal line.
The working order of redundant lines must be tested by their actual use at
reasonable intervals. Dimensioning, test intervals and the basic need for
redundant lines depend directly on the availability requirements of the
network. Similarly, account must be taken of the relation between the
activation time of the redundant line and the recovery time of the normal line.
When answering such questions, it is crucial to know whether the lines are
operated by the public sector (TELEKOM) or by the private sector.
- As regards public-sector lines, the user has no influence on their protection.
The public network generally provides a sufficient number of redundant
lines. In most instances it will suffice, in case of failure of a line (either a
fixed connection or a switched line), to restore the connection by setting up
a switched line. Provision of redundant fixed connections is usually too
expensive and, in most cases, is not absolutely required.
- In a private network, the operator can significantly influence the security of
lines. In most cases, cost considerations result in no redundant lines being
provided. In private networks, however, redundant lines entail no current
expenditure in addition to the cost of production.
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IT-Baseline Protection Manual: Oktober 2000