Troubleshooting guide

Troubleshooting TCP/IP
5-95
6. To determine if there is no network activity at the IP layer between the local
and remote devices, use the debug ppp ipcp command in POS Interface
Configuration mode, as shown in the following example:
RDN(config-if)#debug ppp ipcp
7. If there are problems at the IP layer, such as a wrong routing configuration,
use the show ip route command in Privileged EXEC mode to view the status
of a route with the IP address of the destination device and its connection to
the POS module. Also refer to the routing sections of this document for
information on troubleshooting a specific route.
8. To determine if there is no network activity at the MAC layer between the
local and remote devices, use the debug ppp lcp command in POS Interface
Configuration mode.
RDN(config-if)#debug ppp lcp
9. If there is a link, but no network activity, there might be a Cyclical
Redundancy Check (CRC) level mismatch configuration on the local or
remote device. For example, one device is set for 16 bit and the other for 32
bit. To match the correct CRC bit parameters, use the crc command in POS
Interface Configuration mode:
RDN(config-if)#crc [16 | 32 ]
10. To check if there are significant errors occurring on the other Synchronous
Optical Network (SONET) device, use the show controllers pos command in
POS Interface Configuration mode.
11. Look at the Active Defect field in the show controllers pos command output.
An L-REI indicates high bit error rates from the transmitting (upstream)
device.
12. To the check PPP link statistics, use the show interface pos command in
Global Configuration mode, as shown in the following example.
Note: If the CRC level needs to be adjusted on the remote device, refer to
the remote device’s documentation for information on changing this
parameter.