Specifications

2009
2010
9
INTRODUCTION
As such, this level alone is sufficient for cabling small telecom-
munications networks in a star configuration.
▼ MACHINE ROOMS
Importante come lo studio dell’area di lavoro nella progettazione
è la organizzazione dei locali tecnici, essi non solo definiscono
la centralità del sistema e il loro sviluppo ma sono l’anello di
congiunzione con ampliamenti e successivi livelli degli impianti.
Just as important as the design of the work area is the organi-
sation of the machine rooms: not only do they define the cen-
trality of the system and its extension, but they are the link for
future expansion and additional levels of the system. The ma-
chine rooms must satisfy both certain climatic requirements (tem-
perature, dust, humidity, etc..) but also safety requirements (ac-
cess authorisation, maintenance, administration, etc.) of the
central telecommunications equipment, connections, cabinets
containing switching and network equipment, etc. These spaces
are divided into various areas and should as far as possible not
share the heating, water supply, storage and so on requirements
of the rest of the building.
With reference only to the topology of the system, there are
three distinct classes:
•
Campus distributor
(first hierarchical level);
Campus Distributor (CD): ISO/IEC term;
Main Cross Connect (MC): EIA/TIA term;
•
Building distributor
(second hierarchical level);
Building Distributor (BD): ISO/IEC term;
Intermediate Cross Connect (IC): EIA/TIA term;
•
Floor distributor
(third hierarchical level);
Floor Distributor (FD): ISO/IEC term;
Horizontal Cross Connect: EIA/TIA term.
▼ BACKBONES
When systems are not limited to a solely horizontal exten-
sions or to a single distributor/concentrator, but are extend-
ed over several levels, the connection between the levels is
called a backbone.
Backbones are fundamentally important since their design de-
termines the potential for development, expansion and recon-
figuration of the system.
Backbones are divided into:
• Building or secondary backbones;
• Campus or main backbones.
▼ DISTANCES
The distance between sites is a basic consideration. It is well
known that for any technology employing copper wire, any
two nodes may not be more than 90m apart; beyond this lim-
it optical fibre must be used, which are reach up to 500m be-
tween FD and BD (building backbone) and 2000m between
FD and CD (in other words, the sum of the campus plus build-
ing backbone must be no more than 2 km).
Optical fibre has much higher performance characteristics, but
a cabling system is considered to be a plant covering well de-
fined areas, so that the above limits apply.