HP ProCurve Secure Router 7203 dl Advanced Management And Configuration Manual page 172

Configuring Backup WAN Connections
Viewing Backup Configurations and Troubleshooting Backup Connections
C a u t i o n
3-92
The Call Connects But the Backup Connection Does Not Go Up.
These instructions explain how you can view PPP debug messages to deter-
mine why the Data Link Layer will not go up. However, if a PPP connection is
currently up, these debug messages can swamp the router and seriously
degrade network performance. It can be safer to simply double-check PPP
authentication settings.
Even if the backup connection is the router's only PPP connection, you should
be very careful with PPP debug commands.
Follow these steps:
1. You can view PPP debug messages to determine why the Data Link Layer
will not go up. Enter debug ppp verbose.
2. Look particularly for PPP.AUTHENTICATION messages.
3. Determine whether the local or the remote router cannot authenticate
itself. For CHAP, look for a Challenge message; for PAP, look for an
Authen-Nak. The peer that sends this message is the host that requires its
peer to authenticate itself. (See "Troubleshooting PPP Authentication" on
page 6-62 in the Basic Management and Configuration Guide for more
information on interpreting these debug messages.)
4. If authentication does not seem to be the problem, scan PPP debug
messages for other problems. See troubleshooting tips for PPP in
"Troubleshooting the PPP Interface" on page 6-58 in the Basic Manage-
ment and Configuration Guide.
5. If the remote router requires the local router to authenticate itself, view
the running-config for the backup PPP interface (show run int ppp
<interface number>) and verify that the interface is configured to send
the correct username and password. It must also be using the correct type
of authentication.
The username and password the router sends is listed under ppp pap
sent-username or ppp chap hostname and/or ppp chap password.
The router automatically sends its hostname for the CHAP password. If
necessary, override this hostname with the correct username. (See
"Enabling PPP Authentication" on page 3-56.)
6. If the local router requires the remote router to authenticate itself, view
the running-config for the backup PPP interface (show run int ppp
<interface number>) and verify that the interface contains the correct
username and password for the peer.