Brochure/Catalogue
Segment
The term segment has many meanings. In networks a
segment is a network section delimited by bridges, routers
or switches. Where LANs are concerned, a LAN segment or
a collision domain is referred to. In token ring networks, it
means the transmission section between two neighbouring
data stations. In the TCP specications, a segment describes
a single information unit on the communication network.
Semi-duplex operation
The semi-duplex procedure allows bidirectional use of a
single transmission line. The interfaces, however, can only
either transmit or receive at any given time.
Singlemode
Refer to FO
Slot time
This is an important Ethernet value. The slot time is twice
the speed of the signal propagation time between the two
networks that are farthest away from one another and
the minimum packet length of 64 bytes or 512 bits. At a
frequency clock speed of 10 Mbps, or a frequency clock
cycle of a 100 ns, this produces a slot time of 51.2 µs.
At 100 Mbps the frequency is 10 ns, so therefore the slot
time for the same packet length is 51.2 µs. The greater the
slot time, the poorer the Ethernet performance.
SNMP
The SNMP protocol means that central network
management for many network components is possible.
SNMP’s main objectives are to decrease the complexity of
the management functions, to extend the protocol and to
be independent of any network components. The SNMP
protocol supports monitoring, controlling and administration
of networks. According to the SNMP architecture model
a network is divided into network management stations
(NMS) and network components. The network management
stations carry out applications to monitor and control
the network components. The network components
have management agents, which carry out management
functions.
Spanning Tree Protocol
-> see Rapid Spanning Tree.
ST connector
This LWL-plug (IEC-SC 86B) specied by AT&T is suitable for
both monomode bres and multimode bres. The ST-plug
is a commonly-available plug, used in LANs. It uses a
bayonet lock as its locking system. In this LWL-plug the
FO cable is guided through a ceramic or metal ferrule with
a pin diameter of 2.5 mm and is prevented from twisting
by a metal pin. The ceramic ferrule has been grounded to
make its contact area convex. A spring means that there is
constant contact to the front of the bres to be connected.
Star topology
In star topology the transmission stations are connected
in a star shape to a central node. Star topologies can only
exchange data indirectly via the central node. There is
a difference between active and passive star systems.
In the former, the middle node is a computer that takes
over relaying the messages. Its capacity determines
the performance of the network. For example: private
exchanges. Passive systems only have one node in the
middle that combines the routes. This node does not have
any exchange role, its purpose is signal regeneration. Passive
star systems can for example be operated with TDMA,
CSMA/CD or token access procedures.
Straight-through
A type of cable where the cable connections at both ends
are the same. This type of cable is mostly used to connect
devices such as switches with the station. Straight-through
is the normal way of wiring cables – in contrast to crossover
cables.
Station
Each hardware component in a network and the terminal
equipment connected to the network. Server, router,
telephone, fax machine etc and all communication devices
connected with a network adapter (NIC).
Switching Hub
Switches are network components that have switching
functions. These switching functions can also take place as
exchange functions in long-distance networks and in local
networks. In long-distance networks the local exchanges
have local switches and the remote exchanges have central
switches.
Glossary
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Technical appendix
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