3Com SuperStack II PathBuilder S330 Reference Manual page 108

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HAPTER ONFIGURING
P B S330/S310 M
ATH UILDER ODULES
ATM Cell Mapping — How the carrier will provision the DS3 UNI service from
the carrier ATM switch: Clear (HEC) or PLCP (Physical Layer Convergence
Protocol). Clear is the option preferred by both domestic and international
service providers and within private ATM networks, as it gives more payload
bandwidth than PLCP. You must match this setting at the two ends of the DS3
trunk.
ATM Payload Scramble — Enables (yes) or disables (No) payload scrambling
for the DS3 port. Payload scrambling scrambles the 48-byte payload in
outgoing cells in a defined manner and unscrambles the payload in incoming
cells. It is a technique used to avoid certain transmission equipment behaviors
(for example, erroneous alarm conditions) that are caused by sensitivity to
certain bit patterns in the ATM payload. You must match this setting at the
two ends of the DS3 trunk.
FEAC Loopback (DS3 only) — Enables or disables the system from responding
to FEAC (Far-End Alarm Condition) loopback commands (loopback activate and
deactivate FEAC codes) from the central office. FEAC is a DS3 overhead
function that the service provider may use for establishing loopback for
problem resolution of the network. The service provider uses FEAC codes to
obtain downstream or upstream conditions of a DS3 network. When the FEAC
Loopback option is enabled, the system responds to a loopback activate
command by enabling the DS3 line loopback. The system removes the
loopback automatically after 15 minutes or when it receives the deactivate
command.
DS3 Timing Source (DS3 only) — The timing source for the DS3 transmit
clock: system or loop. If you set the DS3 Timing Source to system at one end of
the DS3 trunk, you must set it to loop at the other end.
System — Configures the DS3 port interface to use the system clock as
defined in the System Clock Configuration menu as its timing source. For
details about designating the system clock, see "Configuring the System
Clock" in Chapter 3.
Loop — Configures the port interface to use the input port Rx clock as the
timing source; timing is received from the service "loop." Select this option
if the DS3 UNI module is used for the network/carrier service termination, in
which case the carrier (the service "loop") typically provides the timing
source.
E3 Timing Source (E3 only) — The timing source for the E3 transmit clock:
system or loop. If you set the E3 Timing Source to system at one end of the E3
trunk, you must set it to loop at the other end.
System — Configures the E3 port interface to use the system clock as
defined in the System Clock Configuration menu as its timing source. For
details about designating the system clock, see "Configuring the System
Clock" in Chapter 3.
Loop — Configures the port interface to use the input port Rx clock as the
timing source; timing is received from the service "loop." Select this option
if the E3 UNI module is used for the network/carrier service termination, in
which case the carrier (the service "loop") typically provides the timing
source.
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ORTS AND PPLICATIONS