19
CHAPTER 3: Configuration and Installation
3.3.3 T
HE
J
UMPER
B
ANKS ON THE
I
NTERFACE
B
OARDS
The FradSwitch A/S 3 Port’s main-link ports can be any of these interfaces, each of
which is controlled by an interface-specific “interface board” (daughterboard)
mounted on the main circuit board:
• EIA/TIA RS-232 (ITU-T V.24)
• EIA/TIA RS-530
• ITU-T V.35
• ITU-T X.21
• DDS CSU/DSU (Port 1 only)
Each interface board can be configured as DCE or DTE by moving the jumper
bank on that board. The jumper bank, marked “DCE
↔
DTE,” consists of
interlinked multiple jumpers that must be moved together, as shown in Figure 3-3
below.
Figure 3-3. A DTE/DCE jumper bank (interface board for an X.21 port
shown).
When a board is set as DTE, the port receives its clock from outside and so must be
firmware-configured for “external clock.” By contrast, when a board is set as DCE,
the port uses the Switch’s own clock and so must be configured for “internal
clock.” (Refer to the
Packet Switching Guide
for more information.)
U1-X21
DTE
↔
DCE
