IT Baseline Protection Manual - The Information Warfare Site

Safeguard Catalogue - Communications Remarks
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Disadvantages:
- Failure of the central node will result in the failure of all connected IT
systems.
- Extensive cabling is required due to the separate linkage of each subscriber
to the central node.
- With an increasing number of individual lines, the risk of cross-talk will
increase.
- Cabling in star configuration might restrict the communications range,
depending on the cable type and communications protocol in use (refer to
S. 5.3 Selection of cable types suited in terms of communications
technology). Repeaters can be used to solve this problem, although they
prove very expensive if a large number of lines is involved. Furthermore, it
is not possible to insert any required number of repeaters into a line. The
maximum number here also depends on the protocol in use. Another
alternative is to convert the network to a tree configuration.
Tree
A tree structure is formed by linking together several star networks. In this
case, the network subscribers are assigned to groups which are connected in
star configuration to decentral network nodes. These decentral network nodes
are linked mutually via one line or several dedicated lines. In certain cases, all
the decentral nodes are also routed to one central network node.
Advantages:
- As concerns a linkage of the systems to the decentral network nodes, the
same advantages apply here as in the case of the star network.
- For new subscribers, new cabling is required only in the area of the
corresponding decentral network node.
- Given an appropriate configuration of the decentral network nodes, an
exchange of data between the subscribers of any particular node is possible
even if the other nodes fail.
- Connecting the decentral nodes to each other via a single line reduces the
cabling requirements.
- Amplification on a single line is sufficient for bridging large distances
between the nodes (cost saving).
- It is advisable to link the nodes by means of (usually more expensive)
high-quality cables, which can also bridge large distances without the need
for additional amplification. As compared with the repeater option which
would otherwise be required, this offers advantages in terms of reduced
costs and increased reliability.
- A tree structure allows the establishment of redundant links through the
meshing of the individual nodes.
Disadvantages:
- Failure of a transition from one decentral network to another will disrupt
the operations of all the connected subscribers.
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IT-Baseline Protection Manual: Oktober 2000