IT Baseline Protection Manual - The Information Warfare Site

Safeguard Catalogue - Communications Remarks
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Bus
In the case of a bus, all network subscribers are connected to a common line.
This line usually consists of a central cable, to which the individual
subscribers are connected via breakout cabling.
Advantages:
- Cabling is reduced to just one cable and any breakout cabling which might
be required.
- A subsequent installation of new subscribers generally requires only
minimal cabling: the subscribers are simply connected to the existing bus
cable.
- A bus can be easily extended through the use of repeaters. However, it
must be noted that such extensions are restricted in length in accordance
with the type of cable and protocol used (refer to S 5.3 Selection of cable
types suited in terms of communications technology).
- Resources can be connected to almost any point on the bus.
- Due to the central cable, the bus cabling takes up much less space than a
comparable star configuration with a TP cable.
Disadvantages:
- Interferences in the cable line affect the entire bus.
- An interruption in the bus cable completely paralyses data
communications.
- From a certain bus length and number of subscribers onwards, the bus can
no longer be extended easily.
- Depending on the type of cable in use, restrictions need to be observed
when connecting new subscribers (e.g. the minimum distance between two
subscribers).
Ring
Topographically, a ring is a bus whose two ends are connected together. One
special type of ring consists of a double-ring like that used with FDDI, for
example.
Advantages:
- If a line is interrupted, a ring can continue operation to a limited extent.
The type of limitation depends on the network access protocol used for the
ring and can involve, for example, losses in bandwidth..
- The optional, double-ring design provides additional redundancy and
failure tolerance.
Disadvantages:
- A restricted number of protocols is available for the ring and double-ring
systems, i.e. not all protocols can be used on these systems. This can prove
disadvantageous for the future development of a network.
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IT-Baseline Protection Manual: Oktober 2000