This flowchart helps you to locate which LCP parameters your PPP local machine is not negotiating with the PPP remote peer. The flowchart below highlights several of the most common PPP LCP parameters that can be negotiated during the LCP phase. To troubleshoot this problem, refer to the Modems do train up okay, PPP starts, but the call later drops section in the Troubleshooting Modems document.įor more detailed information on modem troubleshooting, refer to Troubleshooting Modems. This destroys any chance of receiving incoming LCP frames from remote routers. The modems of both the local and remote routers do train up okay, and PPP starts on both routers, but the call immediately drops. To troubleshoot this problem, refer to the Modems do train up okay, but PPP does not start section in the Troubleshooting Modems document. The modems of both the local router and the remote router train up, but PPP does not start on the remote router. In this case, the problem could be due to one of two possibilities: Outgoing LCP frames are seen on the local router, but there are no incoming LCP frames. This section explains how Asynchronous Modems can be used for PPP connectivity. PPP Link Control Protocol (LCP) PhaseĪsynchronous Modems used for PPP Connectivity Note: In order to troubleshoot successfully, do not skip any of the steps shown in these flowcharts. This document includes some flowcharts to assist in troubleshooting. Refer to Cisco Technical Tips Conventions for more information on document conventions. Depending on where the debug session is run, the dialin client could be the local machine or peer. Note: The terms local machine and peer do not imply a client-server relationship. However, if you shift the debugging over to RouterB, then it becomes the local machine and RouterA becomes the peer. Therefore, this device is not the local machine.įor example, if you run the debug ppp negotiation command on RouterA, this is the local machine, and RouterB is the peer. Peer: The other end of the point-to-point link. As you move the debug session from one router to the other, apply the term "local machine" to the other router. Local machine (or local router): This is the system the debugging session is currently being run on.
#Simutech troubleshooting flowchart software#
This document is not restricted to specific software and hardware versions. If debug ppp negotiation does not indicate that LCP is open, troubleshoot this issue before you proceed. The PPP authentication phase does not begin until the Link Control Protocol (LCP) phase is complete and is in "open" state. Refer to Understanding debug ppp negotiation Output for more information. You must read and understand the debug ppp negotiation output. Prerequisites RequirementsĮnable debug ppp negotiation and debug ppp authentication.
#Simutech troubleshooting flowchart serial#
However, the same troubleshooting steps apply to connections to other routers (such as branch offices) with PPP connections when using Dialer Rotary-Group, Dialer Profile, or PPP over serial links.įor further information on Point-to-Point Protocol, and its supported features in Cisco IOS® software, refer to Cisco Learning Connection ( registered customers only) and search using the keyword ppp in the Search for training field.įor a detailed explanation of the different phases of PPP negotiation and the output of debug ppp negotiation, refer to Configuring and Troubleshooting PPP Password Authentication Protocol (PAP). In the flowcharts and sample output shown below, we have set up an Integrated Services Digital Network (ISDN) basic rate interface (BRI) PPP connection to another using Legacy Dialer-on-Demand Routing (DDR). This flowchart helps you to troubleshoot Point-to-Point Protocol (PPP), which is widely used for multiple Access technology solutions.