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Troubleshooting for PPPoE Connection Failure - Part 1-

     

    Introduction

    I will be summarizing the troubleshooting method for PPPoE connection failure using the specific connection failure examples and debug logs. I will post this topic in several articles.

    1. Checking the Connection Status

    As a first step, you will need to check if the PPPoE session connection has been established successfully. You will use the following command output to check the connection.

    * This is the result obtained by a router operated as the PPPoE client using IOS 15.0M.

    • Not connected              

    PPPoE_Client# show ppp all      

    Interface/ID OPEN+ Nego* Fail-     Stage    Peer Address    Peer Name

    ------------ --------------------- -------- --------------- --------------------

    PPPoE_Client#

    PPPoE_Client# show pppoe session   

         1 client session

    Uniq ID  PPPoE  RemMAC          Port                    VT  VA         State

               SID  LocMAC                                      VA-st      Type

        N/A      0  0000.0000.0000  Et0/0                  Di1  N/A        SHUTDOWN

                    0000.0000.0000                                            

    * Nothing appears because it is not connected.

    • Successfully connected

    PPPoE_Client# show ppp all

    Interface/ID OPEN+ Nego* Fail-     Stage    Peer Address    Peer Name

    ------------ --------------------- -------- --------------- --------------------

    Vi2          LCP+ IPCP+ CDPCP-     LocalT   192.168.1.1     PPPoE_Serv

    PPPoE_Client#

    PPPoE_Client# show pppoe session

         1 client session

    Uniq ID  PPPoE  RemMAC          Port                    VT  VA         State

               SID  LocMAC                                      VA-st      Type

        N/A      2  aabb.cc00.d300  Et0/0                  Di1  Vi2        UP     

                    aabb.cc00.d400                                         UP

    * The sessions for both PPPoE and PPP are displayed.                        

    2. Troubleshooting for Connection Failure

    Incorrect settings are often the cause of issues where the connection was not established within the installation schedule when trying to establish the connection.

    The following are typical examples.

    1. Incorrect router settings for the IP address assignment (auto/fixed)
    2. Incorrect password settings
    3. Authentication method negotiation failure
    4. MTU negotiation failure

    For "1. Incorrect router settings for the IP address assignment (auto/fixed)," troubleshoot the problem using the CCO document as reference. For the other problems, it could be an issue that depends on the destination equipment or it is difficult to determine where and what to fix by looking at show running-config. Please obtain debug logs by enabling debugging. You can identify the cause of the connection failure by checking the results of debug logs.

    The debug logs you are recommended to obtain in the first step are as follows:

    debug ppp authentication

    debug ppp negotiation

    debug pppoe event

    The CCO document introduces the detailed description of how to check the obtained debug logs. Please see the CCO document as well.

    Understanding debug ppp negotiation Output

    http://www.cisco.com/c/en/us/support/docs/wan/point-to-point-protocol-ppp/25440-debug-ppp-negotiation.html

    Related Information

    Original Document: https://supportforums.cisco.com/ja/document/92886
    Author: Katsunori Ishizuka
    Posted on February 23, 2012

    Troubleshooting for PPPoE Connection Failure - Part 2 -
    Troubleshooting for PPPoE Connection Failure - Part 3 -

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