S 2.395 Requirements analysis for IT cabling

Initiation responsibility: Building Services, Head of IT, Planner

Implementation responsibility: Planner, Building Services, Head of IT

Various questions need to be addressed when analysing the requirements that may affect the economic efficiency of the IT cabling installation and its ability to meet all current and future requirements.

The question usually given the most prominence is the question of what data throughput is required. In order to answer this question, the planned usage by the users in the organisation in the short term is estimated first and, building on that, the development of the IT usage over a longer term is estimated.

Two developments must be taken into account in this regard:

On the one hand, the price of bandwidth is continually dropping. The result is that services offered by and procured from third parties place constantly higher demands on the capacity of the IT cabling. In addition to typical IT services such as email and the internet, services ranging from voice and video transmissions to digital television are now being added to IT network services. The resulting increase in bandwidth demand must be taken into account when selecting the quality of the IT cabling.

On the other hand, IT networks are becoming carriers for more and more applications. All applications able to use the protocols and standards of the IT world will probably also use them. This means that an IT network and therefore the IT cabling will not only serve as a communications carrier between computers in the future. Telephony and applications previously dependent their own application-specific network technology will be developed further to utilise standardised IT technology. As a consequence of these foreseeable developments the number of connections needs to be planned accordingly and no part of the building can be left out when planning the IT cabling. Furthermore, the cabling inside a building must be designed to be flexible and expandable, since a change in the use of a room or a part of a building also means a change in the requirements placed on network connections.

In spite of the standardisation of the technology, it is necessary in some cases to plan different or separate cables for certain applications. In particularly sensitive areas of application such as alarm signalling technology or machine and plant control technology, it will be appropriate or even necessary to use separate cables and switching technology for such applications. If the areas of application have different protection requirements and cannot be protected in any other way (e.g. using VPNs), they should generally be separated.

Availability

The protective goal of availability is primarily pursued by careful planning and execution of the cable trays. If the requirements of the users specify that the connection and the network infrastructure of the building must remain usable even during more comprehensive incidents, this must be aimed at with the help of a well thought through redundant route (see S 6.103 Redundancies for the primary cabling, S 6.104 Redundancies for the secondary and tertiary cabling).

Integrity

Shielding against external influences is the top priority to ensure the integrity of the data transported. This means, above all, that the IT cabling is to be routed separately from the electrical cabling. In addition, it must be determined which cable types are suitable to meet the application demands (see S 5.3 Selection of cable types appropriate in terms of communications technology).

Confidentiality

If the confidentiality of the data transported, i.e. the security against interception of the cable, is an important aspect, fibre optic cables (FOC) are the first choice. Fibre optic cables require the potential eavesdropper to use much more complicated technology than all copper-based solutions.

The protection of distributors and connection sockets is even more important in order to prevent normal IT devices from being connected to the local network in an attempt to tap into the network. This also applies, of course, to fibre optic cabling.

In many cases, the confidentiality and integrity of the transported data can be protected using cryptographic procedures as an alternative or as a complement, provided that the terminal devices connected and transmission protocols used support encryption. However, cryptographic procedures only provide additional protection for the availability in special cases.

Additional requirements

Note also that power can or must be supplied to active components such as IP telephones or WLAN access points through the IT cabling. Copper cabling must be used wherever these types of devices will be connected, because power can only be supplied through copper cables.

Review questions:

• Is there a requirements analysis for IT cabling, taking into consideration different fields of application, as well as the aspects of availability, integrity, and confidentiality?