Glossary
739
refers to a collection of ESs and ISs controlled by only one administrative
domain, using a solitary network connection protocol.
summarization
Term used to describe the process of summarizing mul-
tiple routing table entries into one entry.
supernetting
See: summarization.
SVC
switched virtual circuit: A dynamically established virtual circuit, cre-
ated on demand and dissolved as soon as transmission is over and the circuit
is no longer needed. In ATM terminology, it is referred to as a switched
virtual connection. See also: PVC.
switch
1) In networking, a device responsible for multiple functions such
as filtering, flooding, and sending frames. It works using the destination
address of individual frames. Switches operate at the Data Link layer of the
OSI model. 2) Broadly, any electronic/mechanical device allowing connec-
tions to be established as needed and terminated if no longer necessary.
switch block
A combination of layer-3 switches and layer-3 routers. The
layer-2 switches connect users in the wiring closet into the access layer and
provide 10 or 100Mbps dedicated connections. 1900/2820 and 2900 Cata-
lyst switches can be used in the switch block.
switch fabric
Term used to identify a layer-2 switched internetwork with
many switches.
switched LAN
Any LAN implemented using LAN switches. See also:
LAN switch.
synchronous transmission
Signals transmitted digitally with precision
clocking. These signals have identical frequencies and contain individual
characters encapsulated in control bits (called start/stop bits) that designate
the beginning and ending of each character. See also: asynchronous trans-
mission and isochronous transmission.
syslog
A protocol used to monitor system log messages by a remote device.
T reference point
Used with an S reference point to change a 4-wire ISDN
network to a two-wire ISDN network.
T-1
Digital WAN that uses 24 DS0s at 64K each to create a bandwidth
of 1.536Mbps, minus clocking overhead, providing 1.544Mbps of usable
bandwidth.
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