Specifications

2-72
Cisco IGX 8400 Series Provisioning Guide, Release 9.3.3 and Later Releases
OL-1166-04
Chapter 2 Cisco IGX 8400 Series Cards
Frame Relay Module
Figure 2-32 FR Data Clocking Modes on FRI-V.35 Back Card
Note In looped clocking, the clock is looped by the FRI-V.35 back card, not the connected user device.
Port Testing on the FRI-V.35 Back Card (for Ports Configured DTE Only)
For ports configured for DTE, local and remote loopback port tests are also available. In test mode, the
card transmits a loopback data pattern to initiate the loopback. Attached modems or NTUs might or
might not recognize the loopback initiation pattern. If the modem or NTU does not recognize the
loopback initiation pattern, the modem or NTU will not perform the requested loopback. The FRI waits
a programmable time period (default=10 seconds) before sending the test pattern. After the test is
completed, pattern transmission terminates and the circuit returns to normal operation.
Some external equipment supports loopback testing but does not recognize the test pattern (Test Mode)
in the data stream. In these cases, the FRM/FRI toggles the V.35 local loopback (LLB) and the remote
loopback (RLB) leads then runs the test pattern. The FRM/FRI still waits the user-specified time
(default=10 seconds) before running the data test pattern.
To display test results, use the switch software tstport command.
User device
(DTE)
FRI
(DCE)
User device
(DTE)
FRI
(DCE)
TxD
TxC
A. Normal clock - TxC and RxC must be the same frequency
XD
RD
H8071
XTC (not used)
TxD
XTC
B. Looped clock - User device loops clock
XD
RD
TxC (not used)
RxD
CLK
CLK