H3C Technologies H3C SecPath F1000-E - Manual (Page 150)

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PPP configuration examples
NOTE:
PPP works with PPPoE and L2TP. For PPP configuration examples, see "Configuring PPPoE " and VPN
Configuration Guide.
Troubleshooting PPP configuration
Symptom 1
PPP authentication always fails, preventing the link from going up.
Solution
This problem may occur if the parameters for authentication are incorrect.
• Enable the debugging of PPP, and you can see the information describing that LCP went up upon a
successful LCP negotiation but went down after PAP or CHAP negotiation.
• Check the PPP authentication settings at the local and peer ends to make sure that they are
consistent. See " Configuring PAP authentication " and " Configuring CHAP authentication " for
reference.
Symptom 2
Physical link is down.
Solution
Check that:
• The interface has been brought up.
• The interface has not been administratively shut down.
• LCP negotiation has passed.
Execute the display interface serial command to check the state of the interface. The output information
can be:
•
serial number is administratively down, line protocol is down
, which indicates that the
interface is shut down by the administrator.
•
serial number is down, line protocol is down
, which indicates that the interface is not activated
or the physical layer has not gone up yet.
•
Virtual-template number is down, line protocol is spoofing up
, which indicates that the
interface is a dialer interface and the call establishment attempt has failed.
•
serial number is up, line protocol is up
, which indicates that LCP negotiation succeeded.
•
serial number is up, line protocol is down
, which indicates that the interface is active, but
LCP negotiation failed.
NOTE:
The firewall does not support serial interfaces.