System information

Troubleshooting IBM 10-235
SDLC: Router Cannot Communicate with SDLC Device
Link-layer problem (router is
secondary)
Step 1 Use the debug sdlc privileged exec command to see whether the router
is receiving SNRMs.
Caution: Because debugging output is assigned high priority in the
CPU process, it can render the system unusable. For this reason, use
debug commands only to troubleshoot specific problems or during
troubleshooting sessions with Cisco technical support staff. Moreover,
it is best to use debug commands during periods of lower network
traffic and fewer users. Debugging during these periods decreases the
likelihood that increased debug command processing overhead will
affect system use.
Step 2 If the router is not receiving SNRMs, check the primary device. Make
sure the physical layer is operational (see the problem “Physical layer
problem” in this table). If the router is receiving SNRMs, it should send
UAs in reply.
Step 3 If the router is not sending UAs, make sure the addresses of the router
and device are correct.
Step 4 If you are using a V.35 connection, make sure that the SCT/SCTE
setting is correct on the interface. The router should use SCTE if the
router is DCE and SCT if the router is DTE.
The SCT/SCTE setting might be changed with a jumper
or with the software configuration command dce-terminal-timing
enable, depending on the platform. Some platforms do not allow you to
change this setting.
Example:
The following example prevents phase shifting of the data with respect
to the clock:
interface serial 0
dce-terminal-timing enable
Step 5
Use a breakout box to check for CTS high on the line.
Step 6 Make sure that both the device and the router are using the same signal
coding (NRZ or NRZI). NRZ is enabled by default on the router. To
enable NRZI encoding, use the nrzi-encoding interface configuration
command.
Possible Problem Solution