IT Baseline Protection Manual - The Information Warfare Site

Safeguard Catalogue - Communications Remarks
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does not support broadcasts or MAC addresses, which is a prerequisite for the
use of most protocol stacks such as TCP/IP and SPX/IPX. Three different
solutions to this problem are available:
- Classical IP-over-ATM (CIP)
RFC 1577 (Classical IP-over-ATM) was developed for the use of IP over
ATM; this standard allows stations with a TCP/IP protocol stack to use
ATM as a transfer medium.
- LAN Emulation (LANE)
This standard emulates all relevant LAN technologies for clients on layer 2
of the OSI model. In this case, ATM is then represented as, for example, an
Ethernet or Token-Ring network to the clients. This allows
communications between conventional LANs and ATM.
- Multiprotocol-over-ATM (MPOA)
MPOA is basically an advancement of the classical ATM and LANE. In
contrast to LANE, MPOA operates on layer 3 of the OSI model and uses
LANE for transmission on layer 2. Consequently, MPOA implements
bridging (layer 2) as well as routing (layer 3), and can thus configure a
fully routed ATM network. At the same time, it offers all the advantages of
ATM technology, such as guaranteed bandwidths for individual
applications.
Furthermore, it must be noted that no compatibility or interoperability is
presently guaranteed between ATM components from different manufacturers.
A corresponding check is therefore required in each case.
As mentioned at the start, a general recommendation concerning the selection
of a suitable backbone technology cannot be made. In addition to security
requirements, influential factors here include criteria concerning future
orientation, economy, scalability and the integration of existing components.
Depending on the selected protocol, only certain types of cable can be used
(e.g. optical fibre cables for FDDI); each cable type is restricted in length (also
refer to S 5.2 Selection of an appropriate network topography).
Additional controls:
- Have requirements concerning the availability, bandwidth and performance
of the backbone of the local network been formulated and documented?
- Have all the relevant backbone technologies been considered?
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IT-Baseline Protection Manual: Oktober 2000