TeleBoss 850 2.06.280_STD User Manual
Page 205
DSLAM
A
D
igital
S
ubscriber
L
ine
A
ccess
M
ultiplexer is a mechanism at a phone company's central location that links many
customer DSL connections to a single high-speed
line. When the phone company receives a DSL signal, an
ADSL modem with a splitter detects voice calls and data. Voice calls are sent to the PSTN (Public Switched
Telephone Network), and data are sent to the DSLAM, where it passes through the ATM to the Internet, then back
through the DSLAM and ADSL modem before returning to the customer's PC or networked-device.
LLC and VCM
L
ogical
L
ink
C
ontrol and
V
irtual
C
hannel
M
ultiplexing are methods of encapsulating data on an ATM communication
link. Encapsulation is the process of storing cells from the foreign protocol inside PPP frames.
PPP
P
oint-to-
P
oint
P
rotocol is a method of connecting a PC or networked-device to the Internet.
Setting Keys
A Setting Key is a "<setting> = <value>" statement. <setting> is a series of keywords that describe a particular
function of the unit, or setting. These keywords are separated by periods, for example
net.dsl.startmode
. The
current value of a Setting Key can be obtained by typing
sk <setting>
at the command line and pressing the Enter
key. A new value for a Setting Key can be set by typing
sk <setting> = <value>
and pressing the Enter key. The
value must be valid for that particular Setting Key, and the unit will respond with COMPLETE when it is accepted. If
the value is invalid, the unit will respond with Invalid Value. Contact
Setting Keys if necesary.
Signal-to-noise ratio
Signal-to-noise ratio is an electrical engineering concept defined as the ratio of a signal power to the noise power
corrupting the signal. In less technical terms, signal-to-noise ratio compares the level of a desired signal to the level of
background noise. The higher the ratio, the less obtrusive the background noise is.
Trained
This refers to the general ability of a modem to adjust itself to optimize the communication channel. When a modem
modulates data on a line, the communication infrastructure degrades the data. Some of this degradation is due to
noise and some of it is due to the modem's own echo. Part of training the modem (also sometimes referred to as
"training the line") involves having the modem select optimal
as well as teaching the modem what
its own "voice" (its echo) sounds like on the line. A modem receives not only data from the other modem but also its
own echoes, like when you yell to someone across a canyon and listen for their response; training helps the modem
separate its own echos from the signal from the other modem.
VCI
A
V
irtual
C
hannel
I
dentifier is a unique identifier which indicates a particular virtual circuit on a network. It is a 16-bit
cell. The VCI, together with the
(Virtual Path Identifier) is used to identify the next
destination of a cells as it passes through a series of ATM switches on its way to its destination.
VPI
V
irtual
P
ath
I
dentifier refers to an 8-bit (user to network packets) or 12-bit (network-network packets) field within the
cell. The VPI, together with the
(Virtual Channel Identifier) is used to identify the next
destination of a cell as it passes through a series of ATM switches on its way to its destination. VPI is useful to reduce
the switching table for some Virtual Circuits which have common path.
VPN
V
irtual
P
rivate
N
etwork is a network that is tunneled (the virtual part), typically across a public network, and secured
(the private part).
Summary of Contents for Teleboss 850
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