IT Baseline Protection Manual - The Information Warfare Site

Safeguard Catalogue - Organisation Remarks
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S 2.139 Survey of the existing network environment
Initiation responsibility: Head of IT Section, IT Security Management
Implementation responsibility: Administrators
A survey of the existing network environment is required for a systematic
security analysis of the network. Such a survey is also needed if an existing
network needs to be extended. The items described below must be taken into
consideration during the planning of a network.
A survey of the existing environment must be accompanied by a detailed
documentation of the following aspects, which partly depend on each other:
- Network topography
- Network topology
- Network protocols in use
- LAN / WAN connections
- Network performance and traffic flow
The essential details to be recorded during each individual step are specified in
the following:
Survey of the existing network topography
A survey of the existing network topography involves a recording of the
network's physical structure. Here, it is advisable to use the spatial structure of
the network as orientation. A plan containing the following features should be
prepared and maintained:
- Current cable routing
- Locations of all network subscribers, in particular, the active network
components in use
- Cable types in use
- Specified requirements concerning the protection of cables (S 1.22
Physical protection of lines and distributors)
. To support the maintenance of this plan, it is advisable to use an appropriate
tool (e.g. CAD programs, special tools for network plans, cable management
tools in conjunction with system management tools, etc.). Regular updating of
these plans following rebuilding or extension must be ensured, in addition to
clear and precise documentation (also refer to S 1.11 Plans detailing the
location of supply lines and S 5.4 Documentation on and marking of cables).
Survey of the existing network topology
A survey of the existing network topology involves a consideration of the
logical structure of the network. For this purpose, it is necessary to make a
record of the segmentation of the individual OSI layers and, if applicable, the
VLAN structure.
The representation of the network topology should make it possible to
determine the active network components via which a link can be established
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IT-Baseline Protection Manual: Oktober 2000