As with most troubleshooting on Cisco routers, administrators have a wide range of show and
debug commands available to resolve problems that can occur with the Point-to-Point Protocol.
Using standard troubleshooting methodologies, the administrator should be able to isolate
physical problems quickly and then use these tools to locate and resolve logical issues.
Ideally, designers and administrators unfamiliar with PPP will need to implement a simple
configuration before adding additional features such as authentication and multilink bonding.
However, one or both of these services might be required as part of the initial installation. The
debug and show commands will quickly help isolate the various issues.
This section focuses on the three most common debug commands:
debug ppp authentication
debug ppp negotiation
debug ppp packet