Filter
Top Products
61225101L1-5B 15
Loopbacks may be initiated via the VT100 test
screens, front panel pushbuttons, Nx64K port control
leads, or by receiving V.54 or PN127 in-band looping
signals. Not all loopback types are available for all
ports and port services by all initiating sources. See
Table 9 for an overview. A key to the symbols
displayed in Table 9 is available below the Table.
Table 9. Loopback Overview
Ports
Customer, away
from SHDSL Port (left)
Network, toward SHDSL
Port (right)
Services
Initiating Source
Nx64k Port G.703 Port SHDSL Port G.704 Service Nx64k Service
VT100 Test Screens
VT100 Loopback On
(Initiates one of five
loopback types,
regardless of the
associated Loopback
Type Option setting.)*
VT100 Loopback Off
LL Button On
(Initiates a Local
Customer Loopback per
the selected port Loopback
Type Option setting)
Single
service
only
Single
service
only
LL Button Off
RL Button On
(Initiates a Remote
Network Loopback per
the remote unit’s selected
port Loopback Type
Option setting)*
RL Button Off
Nx64k Port Control Leads
C141 LL On
(Initiates a Local
Customer Loopback
per the Nx64k port
Loopback Type Option
setting)
C141 LL Off
C140 RL On
(Initiates a Remote
Network Loopback
per the remote unit
Nx64k port Loopback
Type Option setting)*
C140 RL Off
Receive In-band
Preparatory Signal
(Applies the loopback
after detection of
in-band V.54 or PN127
remote looping pattern
per the associated
service Loopback
Type Option setting)
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A N/A
Receive In-band
Termination Signal
(Terminates loopback
after detection of
in-band V.54 or PN127
remote looping pattern)
(Same as
Nx64k Service)
(Same as
Nx64k Port)
(Same as
Nx64k Port)
(Same as
Nx64k Port)
(Same as
Nx64k Port)
(Same as
Nx64k Port)
AIS
AIS
AIS
AIS
AIS
AIS
AIS
AIS
AIS AIS AIS AIS
AIS
AIS
AIS
AIS AIS
AISAIS
In-band Looping Protocol Reception
Key:
Dual Loop
AIS
Nontransparent Loop
Transparent Loop
No Loop
Sends
In-Band
Patterns
Sends
In-Band
Patterns
Sends
In-Band
Patterns
Sends
EOC
Request
Message
Sends
EOC
Request
Message
Sends
In-Band
Patterns
N/A
* The reception of in-band loopback patterns and EOC loopback request messages may be ignored or blocked on certain
SHDSL LTUs installed in Total Access 3000 Systems