S 6.75 Redundant communication links

Initiation responsibility: Head of IT, IS Management Team

Implementation responsibility: Administrator

Depending on the availability requirements, the failure of a communication link or the inability to establish the link can severely impair operations. This applies both to telephone connections as well as to LAN or WAN connections. The sources of error can vary so greatly in this case that it is often very difficult to determine the exact cause of the problem.

Since typical working environments are becoming more and more heavily networked these days, failures of communications links can mean that important data and information cannot be exchanged. Under certain circumstances, this can lead to interruptions in workflows until the connection has been restored or alternative solutions have been found.

It therefore makes sense to hold alternative solutions in reserve for the various communication links (depending on their protection requirements).

Examples:

• The availability of the telephone connection of a control centre should be guaranteed not only over the land-based network, but also over a mobile phone.
• A second Internet provider should be used in addition to the normal Internet provider to guarantee that the email server is able to connect to the outside world.
• In addition to the email connection or a fax server, there should also be a fax machine available in case the network connection or server goes down.

It is not always necessary in this case to have another connection with the same bandwidth and the same quality requirements in reserve. In many cases, it will be sufficient to be able to maintain limited IT operations in an emergency situation (see also module S 1.3 Business continuity management).

Review questions:

• Are there alternative solutions to ensure communication via important network connections?
• Do the alternative solutions meet the organisation's technical security policies?