Information Technology Reference
In-Depth Information
Table10-8
SDLC: Router Cannot Communicate with SDLC Device (continued)
Possible Problem
Solution
1.
Use the
debug sdlc
privileged exec command
4
to see
whether the router is sending SNRMs.
5
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.
2.
If the router is not sending SNRMs, check the physical layer
(see the preceding problem in this table). If the router is
sending SNRMs, the device should send UAs
6
in reply.
3.
If the device is not sending UAs, make sure that the
addresses of the router and device are correct.
4.
If you are using a V.35 connection, make sure that the
SCT/SCTE
7
setting is correct on the interface. The router
should use SCTE if the router is DCE, and it should use 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:
Link-layer
problem (router is
primary)
interface serial 0
dce-terminal-timing enable
5.
Make sure that the device and the router are using the same
signal coding (NRZ
8
or NRZI
9
). NRZ is enabled by default
on the router. To enable NRZI encoding, use the
nrzi-encoding
interface configuration command.
Example:
In the following example, serial interface 1 is configured for
NRZI encoding:
interface serial 1
nrzi-encoding
continues
