HP e3000/iX Network Planning and Configuration Guide (36922-90037)

Glossary 267
Glossary
timer (T3) Length of time that a
link can remain in an idle state.
After the expiration of the timer,
the link is considered to be in a
non-active, non-operational state
and is automatically reset. The
value should be chosen carefully.
In particular, it must be
sufficiently greater than the
retransmission timer (T1) so that
no doubt exists about the link’s
state.
token ring collection of data
communicationsystemssharinga
common cable and
communicating by means of the
IEEE 802.5 protocol. In a token
ring network, access is controlled
by the passing of a token from
node to node. Outgoing messages
are attached to the token and
passed with the token until they
arrive at the node to which they
are addressed.
Token Ring 3000/iX Network
Link Hardware and software
required to connect a HP 3000
Series 900 system to a token ring
network.
topology The physical
arrangement of nodes in a
network. Some common
topologies are bus, star, and ring.
transmission control protocol
TCP. A network protocol that
establishes and maintains
connections between nodes. TCP
regulates the flow of data, breaks
messages into smaller fragments
if necessary (and reassembles the
fragments at the destination),
detects errors, and retransmits
messages if errors have been
detected.
Transpac The national public
PSN of France.
transparent mode Data
transfer scheme in which only a
limited number of special
characters retain their meaning
and are acted on by the system.
All other characters are
considered to be data and are
passed through with no control
actions being taken.
transport, network Software
that corresponds to layers 4 and 3
of the OSI network architecture
model. The function of this
software is to send data out over
the appropriate communications
link, to receive incoming data,
and to route incoming or outgoing
data to the appropriate
destination node.
Tymnet A proprietary public
data network in the USA.
typeahead A facility that allows
terminal users to enter data
before a read is actually posted to
the terminal.
U
unacknowledged frame
number (K) The number of
frames that can be transmitted
without receiving an
acknowledgment from the