Nortel Networks 8000 - Manual (Page 195)

Nortel Secure Router 8000 Series
Configuration -WAN Access 6 PPP and MP configuration
Step 1 Check the connection of the interfaces. If the connection is not correct or the contact is poor,
connect them once again.
Step 2 Check whether the physical attributes of two ends are consistent by using the display
interface command. If not, modify them to be consistent.
Step 3 Run the shutdown and the undo shutdown commands or the restart command in the
interface view to validate the newly configured attributes.
—End
6.13.2 Link is always in the down state
Fault description
After PPP and the authentication parameters are configured, the link is not in the Up state.
Fault analysis
The possible cause is that you have not configured the PPP authentication parameters
correctly or the authentication modes at the two ends are inconsistent.
Troubleshooting procedure
Do as follows on the routers:
Step 1 Enable the debugging and view the authentication status by using the debugging ppp
command. If the LCP negotiation succeeds and turns to Up, and then during PAP or CHAP
negotiation, LCP turns to Down. In this case, modify the authentication configurations and
parameters.
Step 2 Check the interface configuration by using the display interface command. Check whether
the configured parameter is validated. If not, use the shutdown command and the undo
shutdown command or use the restart command in the interface view to restart the interface.
—End
6.13.3 CHAP authentication of a PPP link fails
Fault description
You connect a router applying SR8000 software with that from another vendor. The CHAP
authentication fails.
Fault analysis
The possible cause is that some vendors require the username for authentication on the server
end to be different from the username on the client end. The SR8000 has no such requirement.
Troubleshooting procedure
Do as follows on all the routers:
Issue 5.3 (30 March 2009) Nortel Networks Inc. 6-69