IT Baseline Protection Manual - The Information Warfare Site

Threats Catalogue Deliberate Acts Remarks
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T 2.44 Incompatible active and passive network
components
Incompatible active network components can cause problems with
communications protocols which have not yet been standardised completely,
such as ATM or Tag switching. In such cases, the manufacturer needs to
employ proprietary implementations to offset the missing, or partially
available standards and allow for the use of the affected communications
protocol.
Incompatibilities of this type can be caused if existing networks are extended
with active network components from another vendor or networks are built
using components from different vendors.
If active network components with different implementations of the same
communications protocol are running parallel within the same network, this
may impair the availability of the entire network, individual segments, or
some services within the network. Two different cases can be distinguished
depending on the type of incompatibility:
- Implementations of a communications protocol which are not able to
operate with each other, can make communication between the related
components impossible.
Example: ATM components might use different signalling protocols
which are not able to operate together, e.g. in compliance with UNI (User
Network Interface) Version 3.0 and UNI Version 3.1.
- Even if active network components are able to operate together in
principle, certain services might be implemented in different ways. As a
result, these services may be unavailable or at least not available in some
segments of the network, although communication outside the scope of
these services is still possible.
Example: Proprietary implementations of redundant LAN emulation
servers for ATM networks are in existence. If an ATM network consists of
two ATM switches, one of which possesses such a proprietary
implementation while the other does not, communication based on LANE
(LAN Emulation) is still possible, but the service implemented on a
proprietary basis cannot be used.
A combination of incompatible, passive network components can also impair
the availability of a network. Twisted-pair cables available in 100-ohm and
150-ohm designs cannot be used parallel without the use of the proper
converter. An unsuitable combination of active and passive network
components can also impair availability if, for example, a network access
protocol is used for a medium which has not been foreseen for this purpose.
For instance, ATM is not able to work with a 50-ohm coaxial cable.
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IT-Baseline Protection Manual: Oktober 2000