18
S2-4 through S2-5: Clock Mode
The RocketLink-G can operate in one of three clock modes:
internal
,
external
, or
receive-recover
.
X.21 operation.
There are a few things to note about clock modes and
X.21 operation.
—
One X.21 modem must be set to
Receive-Recover.
The other
X.21 modem must be set to either
Internal
or
External/Network
clock mode.
—
The X.21 modem that is configured as
Receive-Recover
must
be DCE.
—
The X.21 modem that is configured as
Internal
must also be
DCE, but if it is an
External/Network
clock, then the modem
must be configured as DTE.
Ethernet operation.
The 3088RC/C/AI model does not recover clock
from the Ethernet network because it is packet-based rather than TDM.
Therefore, the external clock mode is not valid.
S2-4
S2-5
Clock Mode
Description
ON
ON
Internal
The on-board oscillator in
the 3088RC provides clock
for both serial and DSL
lines.
OFF
ON
External
3088RC uses the RX clock
from the serial interface as
the clock for the DSL link.
ON
OFF
Receive-
Recover
3088RC uses the RX clock
from the DSL line as the
clock for the serial interface.
OFF
OFF
Reserved
CPE-Side Modem
CO-Side Modem
Modem’s X.21
Orientation
Receive-Recover
Internal
External/Network
DCE
DCE
x
DCE
x
DTE