Brochure/Catalogue

OSI
OSI are internationally-agreed standards which open systems
should work with and dene the rules for implementing
these norms. Communications systems are a combination
of network hardware and network and systems software
in a group of networked devices that permit free exchange
of information between these devices on the basis of joint
protocol agreements and interfaces, independently of the
type of these devices or how they are equipped. Systems
that implement OSI protocols are an example of this. The
OSI standards are freely available and not protected by
licences.
Packet
A data packet is a dened arrangement of characters as part
of the data network, that are treated as a unit in transmission
services with data packet transmission. As well as the
payload data, data packets also include control information
for addressing, sequence of transmission, ow control and
error adjustment at all protocol levels. A data packet can be
of a predetermined or variable length, but a maximum length
is specied. If the whole destination address is included in
each data packet, it is called a datagramme. On the other
hand in a virtual connection only the rst data packet has
the whole address, whereas in the following data packets an
assignment is made to the appropriate connection.
Patch cable
In the oor distribution point the patch cable creates a
exible connection between oor distribution point and
the horizontal wiring. Patch cables are FO cables or copper
cables and are also called jumper cords. Patch cables should
be very exible, have a tight bending radius and if possible
should max the xed cable. Patch cables are taken into
account in the ISO/IEC 11801 and EN 50173 standards,
but are not included in the transmission features specied
for the link classes. This should be changed when ie. the
channel standards are revised. The patch cable should then,
at a length of up to 5 m, be part of a new denition, the
channel specication and included in all the transmission
features. The jumper cord and a connection cable, also 5 m
long, will then be taken into account in this specication.
PAUSE
A single frame is sent via the full-duplex mode to the
available stations, to signify that transmissions are to be
reduced.
PCF
Refer to FO
PHY
Physical Layer device. This term is mostly used for a
transceiver in Fast and Gigabit Ethernet.
Physical Layer
The Physical Layer (PHY) is the top sublayer or physical layer
consisting of the PMD-sublayer and the PHY-sublayer. The
PHY-sublayer is underneath the MAC layer and encodes,
decodes and synchronises the station with the transmission
frequency and the regeneration of the transmission
frequency.
PoE (Power over Ethernet)
Power over Ethernet (PoE) is a procedure which allows
power to be supplied to a network compatible device over
the 8-wire Ethernet cable. The rst version of the procedure
is dened under IEEE802.3af and includes performance
classes up to max. 15.4 W. There has since been a further
development called PoE +. The respective standard is
IEEE802.at and it primarily involves an increase in max.
power to 30 W.
Overview of PoE/PoE Plus
PoE PoE Plus
Minimum cable type Cat. 5 Cat. 5
IEEE standard denition 802.3af 802.3at
Maximum power per PSE port 15.4 W 30 W
Maximum power to PD 12.95 W 25.5 W
Twisted pair used 2-pair 2-pair
POF
Refer to FO
Point-to-Point Technology
A type of connection where a connection is generated
between two pieces of terminal equipment. Point-to-Point
connections occur in the networked environment, in radio
broadcasting, in beam radio and in the service area. In
networks, where point-to-point connections are concerned,
instead of a user network interface, an interface to a central
facility in the network can also be operated. The connection
can be permanent or on demand.
Port
Connector on a hardware unit. Usually an input/output
channel on the computer or other hardware unit such as
modem, router, hub or multiplexer.
Glossary
W
Technical appendix
W.112596860000