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Troubleshooting for PPPoE Connection Failure - Part 3 -

CscTsWebDocs
Community Member

‎08-18-2014 09:02 AM - edited ‎03-01-2019 05:03 PM

     

    Introduction

    This is Part 3 of the troubleshooting for PPPoE connection failure. In this article, I will explain specific examples introduced in Part 1.

    5. Authentication Method Negotiation Problems

    The negotiation of the authentication method may fail due to the dependence on the designation method of the authentication method, such as PAP/CHAP or the equipment/settings on the PPPoE server side. To be specific, the case where both CHAP and PAP are enabled for LCP negotiation in the design, allowing only PAP authentication as the PPPoE server authentication method. The connection fails if you set only PAP or CHAP on the PPPoE client side in such cases.

    5-1. When Setting PAP Authentication on PPPoE Client Router

    In this example, CONFREQ [Authentication Protocol is CHAP... ] has been received from the PPPoE server even when the client-side authentication method is set as the PAP authentication. Although only PAP is set on the PPPoE client side, CONFACK was transmitted as [ is CHAP in... ] and the LCP processing ended. In this case, the CHAP authentication is not obviously available, so TERMREQ will be transmitted from the PPPoE client to end the session.

    The negotiation process by the CHAP parameter in LCP

    Vi2 LCP: I CONFREQ [ACKrcvd] id 2 len 19

    Vi2 LCP:    MRU 1454 (0x010405AE)

    Vi2 LCP:    AuthProto CHAP (0x0305C22305)

    Vi2 LCP:    MagicNumber 0xB4D6C5C4 (0x0506B4D6C5C4)

    Vi2 LCP: O CONFACK [ACKrcvd] id 2 len 19

    Vi2 LCP:    MRU 1454 (0x010405AE)

    Vi2 LCP:    AuthProto CHAP (0x0305C22305)

    Vi2 LCP:    MagicNumber 0xB4D6C5C4 (0x0506B4D6C5C4)

    CHAP authentication failure

    Vi2 LCP: State is Open

    Vi2 PPP: Received SENDAUTH Response FAIL

    Vi2 CHAP: Unable to authenticate for peer

    Vi2 PPP DISC: User failed CHAP authentication

    Ending the session by TERMREQ transmitted from the PPPoE client

    Vi2 LCP: O TERMREQ [Open] id 3 len 4

    Vi2 LCP: Event[CLOSE] State[Open to Closing]

    Vi2 PPP: Phase is TERMINATING

    Vi2 LCP: I TERMACK [Closing] id 3 len 4

    Vi2 PPP: No remote authentication for call-out

    Vi2 LCP: Event[Receive TermAck] State[Closing to Closed]

    Vi2 LCP: Event[DOWN] State[Closed to Initial]

    Vi2 PPP: Phase is DOWN

    PPPoE : Shutting down client session

    Debug Log Sample with the PAP Authentication set on the PPPoE Client Side

    * Initially, I was expecting MTU problems as well, so I set MTU1438 (1454 was OK). The logs were acquired with that setting and NAK was returned once at the MRU negotiation, but please ignore it.

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

    %LINK-3-UPDOWN: Interface Virtual-Access2, changed state to up

    Vi2 PPP: Sending cstate UP notification

    Vi2 PPP: Processing CstateUp message

    PPP: Alloc Context [30A59044]

    ppp267 PPP: Phase is ESTABLISHING

    Vi2 PPP: Using dialer call direction

    Vi2 PPP: Treating connection as a callout

    Vi2 PPP: Session handle[7200000B] Session id[267]

    Vi2 LCP: Event[OPEN] State[Initial to Starting]

    Vi2 PPP: No remote authentication for call-out

    Vi2 LCP: O CONFREQ [Starting] id 1 len 14

    Vi2 LCP:    MRU 1438 (0x0104059E)

    Vi2 LCP:    MagicNumber 0x8168668C (0x05068168668C)

    Vi2 LCP: Event[UP] State[Starting to REQsent]

    Vi2 LCP: I CONFNAK [REQsent] id 1 len 8

    Vi2 LCP:    MRU 1454 (0x010405AE)

    Vi2 LCP: O CONFREQ [REQsent] id 2 len 14

    Vi2 LCP:    MRU 1454 (0x010405AE)

    Vi2 LCP:    MagicNumber 0x8168668C (0x05068168668C)

    Vi2 LCP: Event[Receive ConfNak/Rej] State[REQsent to REQsent]

    Vi2 LCP: I CONFACK [REQsent] id 2 len 14

    Vi2 LCP:    MRU 1454 (0x010405AE)

    Vi2 LCP:    MagicNumber 0x8168668C (0x05068168668C)

    Vi2 LCP: Event[Receive ConfAck] State[REQsent to ACKrcvd]

    Vi2 LCP: I CONFREQ [ACKrcvd] id 2 len 19

    Vi2 LCP:    MRU 1454 (0x010405AE)

    Vi2 LCP:    AuthProto CHAP (0x0305C22305)

    Vi2 LCP:    MagicNumber 0xB4D6C5C4 (0x0506B4D6C5C4)

    Vi2 LCP: O CONFACK [ACKrcvd] id 2 len 19

    Vi2 LCP:    MRU 1454 (0x010405AE)

    Vi2 LCP:    AuthProto CHAP (0x0305C22305)

    Vi2 LCP:    MagicNumber 0xB4D6C5C4 (0x0506B4D6C5C4)

    Vi2 LCP: Event[Receive ConfReq+] State[ACKrcvd to Open]

    Vi2 PPP: Queue CHAP code[1] id[1]

    Vi2 PPP: Phase is AUTHENTICATING, by the peer

    Vi2 CHAP: Redirect packet to Vi2

    Vi2 CHAP: I CHALLENGE id 1 len 38 from "PPPoE_Server"

    Vi2 PPP: Sent CHAP SENDAUTH Request

    Vi2 LCP: State is Open

    Vi2 PPP: Received SENDAUTH Response FAIL

    Vi2 CHAP: Unable to authenticate for peer

    Vi2 PPP DISC: User failed CHAP authentication

    Vi2 PPP: Sending AAA radius abort

    Vi2 PPP: Sending Acct Event[Down] id[11A]

    PPP: NET STOP send to AAA.

    Vi2 LCP: O TERMREQ [Open] id 3 len 4

    Vi2 LCP: Event[CLOSE] State[Open to Closing]

    Vi2 PPP: Phase is TERMINATING

    Vi2 LCP: I TERMACK [Closing] id 3 len 4

    Vi2 PPP: No remote authentication for call-out

    Vi2 LCP: Event[Receive TermAck] State[Closing to Closed]

    Vi2 LCP: Event[DOWN] State[Closed to Initial]

    Vi2 PPP: Phase is DOWN

    PPPoE : Shutting down client session

    [0]PPPoE 32670: O PADT  R:000b.4529.ec38 L:7081.05c1.7ec2 Gi0/2

    %DIALER-6-UNBIND: Interface Vi2 unbound from profile Di1

    %LINK-3-UPDOWN: Interface Virtual-Access2, changed state to down

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

    5-2. When Setting CHAP Authentication on PPPoE Client Router

    The connection failed with the PAP authentication set in 5-1, so next I tried a connection with the CHAP authentication set. Unlike 5-1, the CHAP authentication is set on the PPPoE client side, so CHAP RESPONSE is returned to CHAP CHALLENGE and the CHAP authentication starts. However, the PPPoE server side is configured for the PAP authentication, so the CHAP authentication will not complete. After that, it receives CONFREQ of LCP from the PPPoE server and starts LCP negotiation once again for the PAP authentication. But the PAP authentication is not set on the client side, so the LCP negotiation fails and the session ends.

    The following explains the situation where the connection fails.

    The CHAP authentication starts, but without completing this process, it receives CONF REQ (AuthProto PAP) of LCP

    Vi2 CHAP: Redirect packet to Vi2

    Vi2 CHAP: I CHALLENGE id 1 len 26 from "PPPoE_Server"

    Vi2 PPP: Sent CHAP SENDAUTH Request

    Vi2 LCP: State is Open

    Vi2 PPP: Received SENDAUTH Response FAIL

    Vi2 CHAP: Using hostname from interface CHAP

    Vi2 CHAP: Using password from interface CHAP

    Vi2 CHAP: O RESPONSE id 1 len 26 from "PPPoE_Client"

    Vi2 LCP: I CONFREQ [Open] id 1 len 18

    Vi2 LCP:    MRU 1454 (0x010405AE)

    Vi2 LCP:    AuthProto PAP (0x0304C023)

    Vi2 LCP:    MagicNumber 0x3CF0E3AB (0x05063CF0E3AB)

    LCP on the PPPoE client side becomes Down temporarily and the LCP negotiation resumes, but the PAP/CHAP settings do not match

    Vi2 PPP DISC: PPP Renegotiating

    Vi2 PPP: Sending Acct Event[Reneg] id[38]

    PPP: NET STOP send to AAA.

    Vi2 LCP: Event[LCP Reneg] State[Open to Open]

    Vi2 LCP: Event[DOWN] State[Open to Starting]

    Vi2 PPP: Phase is DOWN

            <Omit>

    Vi2 LCP: I CONFREQ [ACKrcvd] id 2 len 18

    Vi2 LCP:    MRU 1454 (0x010405AE)

    Vi2 LCP:    AuthProto PAP (0x0304C023)

    Vi2 LCP:    MagicNumber 0x3CC7AC81 (0x05063CC7AC81)

    Vi2 LCP: O CONFNAK [ACKrcvd] id 2 len 9

    Vi2 LCP:    AuthProto CHAP (0x0305C22305)

    Ultimately, LCP failed to negotiate

    Vi2 LCP: Sent too many CONFNAKs.  Switch to CONFREJ

    Vi2 LCP: Sent too many CONFREJs.  Closing CP

    Vi2 PPP DISC: LCP failed to negotiate

    Debug Log Sample with the CHAP Authentication Set on the PPPoE Client Side

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

    %LINK-3-UPDOWN: Interface Virtual-Access2, changed state to up

    Vi2 PPP: Sending cstate UP notification

    Vi2 PPP: Processing CstateUp message

    PPP: Alloc Context [30746044]

    ppp73 PPP: Phase is ESTABLISHING

    Vi2 PPP: Using dialer call direction

    Vi2 PPP: Treating connection as a callout

    Vi2 PPP: Session handle[3F000057] Session id[73]

    Vi2 LCP: Event[OPEN] State[Initial to Starting]

    Vi2 PPP: No remote authentication for call-out

    Vi2 LCP: O CONFREQ [Starting] id 1 len 14

    Vi2 LCP:    MRU 1454 (0x010405AE)

    Vi2 LCP:    MagicNumber 0x8120C267 (0x05068120C267)

    Vi2 LCP: Event[UP] State[Starting to REQsent]

    Vi2 LCP: I CONFACK [REQsent] id 1 len 14

    Vi2 LCP:    MRU 1454 (0x010405AE)

    Vi2 LCP:    MagicNumber 0x8120C267 (0x05068120C267)

    Vi2 LCP: Event[Receive ConfAck] State[REQsent to ACKrcvd]

    Vi2 LCP: I CONFREQ [ACKrcvd] id 2 len 19

    Vi2 LCP:    MRU 1454 (0x010405AE)

    Vi2 LCP:    AuthProto CHAP (0x0305C22305)

    Vi2 LCP:    MagicNumber 0xB50CD1AF (0x0506B50CD1AF)

    Vi2 LCP: O CONFACK [ACKrcvd] id 2 len 19

    Vi2 LCP:    MRU 1454 (0x010405AE)

    Vi2 LCP:    AuthProto CHAP (0x0305C22305)

    Vi2 LCP:    MagicNumber 0xB50CD1AF (0x0506B50CD1AF)

    Vi2 LCP: Event[Receive ConfReq+] State[ACKrcvd to Open]

    Vi2 PPP: Phase is AUTHENTICATING, by the peer

    Vi2 LCP: State is Open

    Vi2 CHAP: I CHALLENGE id 1 len 38 from "PPPoE_Server"

    Vi2 PPP: Sent CHAP SENDAUTH Request

    Vi2 PPP: Received SENDAUTH Response FAIL

    Vi2 CHAP: Using hostname from interface CHAP

    Vi2 CHAP: Using password from interface CHAP

    Vi2 CHAP: O RESPONSE id 1 len 44 from "PPPoE_Client"

    Vi2 LCP: I CONFREQ [Open] id 1 len 18

    Vi2 LCP:    MRU 1454 (0x010405AE)

    Vi2 LCP:    AuthProto PAP (0x0304C023)

    Vi2 LCP:    MagicNumber 0x3CC7AC81 (0x05063CC7AC81)

    Vi2 PPP DISC: PPP Renegotiating

    Vi2 PPP: Sending Acct Event[Reneg] id[65]

    PPP: NET STOP send to AAA.

    Vi2 LCP: Event[LCP Reneg] State[Open to Open]

    Vi2 LCP: Event[DOWN] State[Open to Starting]

    Vi2 PPP: Phase is DOWN

    PPP: Alloc Context [30745E78]

    ppp73 PPP: Phase is ESTABLISHING

    Vi2 PPP: Using dialer call direction

    Vi2 PPP: Treating connection as a callout

    Vi2 PPP: Session handle[AE000058] Session id[73]

    Vi2 LCP: Event[OPEN] State[Initial to Starting]

    Vi2 PPP: No remote authentication for call-out

    Vi2 LCP: O CONFREQ [Starting] id 1 len 14

    Vi2 LCP:    MRU 1454 (0x010405AE)

    Vi2 LCP:    MagicNumber 0x8120CA65 (0x05068120CA65)

    Vi2 LCP: Event[UP] State[Starting to REQsent]

    Vi2 LCP: I CONFREQ [REQsent] id 1 len 18

    Vi2 LCP:    MRU 1454 (0x010405AE)

    Vi2 LCP:    AuthProto PAP (0x0304C023)

    Vi2 LCP:    MagicNumber 0x3CC7AC81 (0x05063CC7AC81)

    Vi2 LCP: O CONFNAK [REQsent] id 1 len 9

    Vi2 LCP:    AuthProto CHAP (0x0305C22305)

    Vi2 LCP: Event[Receive ConfReq-] State[REQsent to REQsent]

    Vi2 LCP: I CONFACK [REQsent] id 1 len 14

    Vi2 LCP:    MRU 1454 (0x010405AE)

    Vi2 LCP:    MagicNumber 0x8120CA65 (0x05068120CA65)

    Vi2 LCP: Event[Receive ConfAck] State[REQsent to ACKrcvd]

    Vi2 LCP: I CONFREQ [ACKrcvd] id 2 len 18

    Vi2 LCP:    MRU 1454 (0x010405AE)

    Vi2 LCP:    AuthProto PAP (0x0304C023)

    Vi2 LCP:    MagicNumber 0x3CC7AC81 (0x05063CC7AC81)

    Vi2 LCP: O CONFNAK [ACKrcvd] id 2 len 9

    Vi2 LCP:    AuthProto CHAP (0x0305C22305)

    Vi2 LCP: Event[Receive ConfReq-] State[ACKrcvd to ACKrcvd]

    Vi2 LCP: I CONFREQ [ACKrcvd] id 3 len 18

    Vi2 LCP:    MRU 1454 (0x010405AE)

    Vi2 LCP:    AuthProto PAP (0x0304C023)

    Vi2 LCP:    MagicNumber 0x3CC7AC81 (0x05063CC7AC81)

    Vi2 LCP: O CONFNAK [ACKrcvd] id 3 len 9

    Vi2 LCP:    AuthProto CHAP (0x0305C22305)

    Vi2 LCP: Event[Receive ConfReq-] State[ACKrcvd to ACKrcvd]

    Vi2 LCP: I CONFREQ [ACKrcvd] id 4 len 18

    Vi2 LCP:    MRU 1454 (0x010405AE)

    Vi2 LCP:    AuthProto PAP (0x0304C023)

    Vi2 LCP:    MagicNumber 0x3CC7AC81 (0x05063CC7AC81)

    Vi2 LCP: O CONFNAK [ACKrcvd] id 4 len 9

    Vi2 LCP:    AuthProto CHAP (0x0305C22305)

    Vi2 LCP: Event[Receive ConfReq-] State[ACKrcvd to ACKrcvd]

    Vi2 LCP: I CONFREQ [ACKrcvd] id 5 len 18

    Vi2 LCP:    MRU 1454 (0x010405AE)

    Vi2 LCP:    AuthProto PAP (0x0304C023)

    Vi2 LCP:    MagicNumber 0x3CC7AC81 (0x05063CC7AC81)

    Vi2 LCP: O CONFNAK [ACKrcvd] id 5 len 9

    Vi2 LCP:    AuthProto CHAP (0x0305C22305)

    Vi2 LCP: Event[Receive ConfReq-] State[ACKrcvd to ACKrcvd]

    Vi2 LCP: I CONFREQ [ACKrcvd] id 6 len 18

    Vi2 LCP:    MRU 1454 (0x010405AE)

    Vi2 LCP:    AuthProto PAP (0x0304C023)

    Vi2 LCP:    MagicNumber 0x3CC7AC81 (0x05063CC7AC81)

    Vi2 LCP: Sent too many CONFNAKs.  Switch to CONFREJ

    Vi2 LCP: O CONFREJ [ACKrcvd] id 6 len 8

    Vi2 LCP:    AuthProto PAP (0x0304C023)

    Vi2 LCP: Event[Receive ConfReq-] State[ACKrcvd to ACKrcvd]

    Vi2 LCP: I CONFREQ [ACKrcvd] id 7 len 18

    Vi2 LCP:    MRU 1454 (0x010405AE)

    Vi2 LCP:    AuthProto PAP (0x0304C023)

    Vi2 LCP:    MagicNumber 0x3CC7AC81 (0x05063CC7AC81)

    Vi2 LCP: Sent too many CONFNAKs.  Switch to CONFREJ

    Vi2 LCP: O CONFREJ [ACKrcvd] id 7 len 8

    Vi2 LCP:    AuthProto PAP (0x0304C023)

    Vi2 LCP: Event[Receive ConfReq-] State[ACKrcvd to ACKrcvd]

    Vi2 LCP: I CONFREQ [ACKrcvd] id 8 len 18

    Vi2 LCP:    MRU 1454 (0x010405AE)

    Vi2 LCP:    AuthProto PAP (0x0304C023)

    Vi2 LCP:    MagicNumber 0x3CC7AC81 (0x05063CC7AC81)

    Vi2 LCP: Sent too many CONFNAKs.  Switch to CONFREJ

    Vi2 LCP: O CONFREJ [ACKrcvd] id 8 len 8

    Vi2 LCP:    AuthProto PAP (0x0304C023)

    Vi2 LCP: Event[Receive ConfReq-] State[ACKrcvd to ACKrcvd]

    Vi2 LCP: I CONFREQ [ACKrcvd] id 9 len 18

    Vi2 LCP:    MRU 1454 (0x010405AE)

    Vi2 LCP:    AuthProto PAP (0x0304C023)

    Vi2 LCP:    MagicNumber 0x3CC7AC81 (0x05063CC7AC81)

    Vi2 LCP: Sent too many CONFNAKs.  Switch to CONFREJ

    Vi2 LCP: O CONFREJ [ACKrcvd] id 9 len 8

    Vi2 LCP:    AuthProto PAP (0x0304C023)

    Vi2 LCP: Event[Receive ConfReq-] State[ACKrcvd to ACKrcvd]

    Vi2 LCP: I CONFREQ [ACKrcvd] id 10 len 18

    Vi2 LCP:    MRU 1454 (0x010405AE)

    Vi2 LCP:    AuthProto PAP (0x0304C023)

    Vi2 LCP:    MagicNumber 0x3CC7AC81 (0x05063CC7AC81)

    Vi2 LCP: Sent too many CONFNAKs.  Switch to CONFREJ

    Vi2 LCP: O CONFREJ [ACKrcvd] id 10 len 8

    Vi2 LCP:    AuthProto PAP (0x0304C023)

    Vi2 LCP: Event[Receive ConfReq-] State[ACKrcvd to ACKrcvd]

    Vi2 LCP: I CONFREQ [ACKrcvd] id 11 len 18

    Vi2 LCP:    MRU 1454 (0x010405AE)

    Vi2 LCP:    AuthProto PAP (0x0304C023)

    Vi2 LCP:    MagicNumber 0x3CC7AC81 (0x05063CC7AC81)

    Vi2 LCP: Sent too many CONFNAKs.  Switch to CONFREJ

    Vi2 LCP: O CONFREJ [ACKrcvd] id 11 len 8

    Vi2 LCP:    AuthProto PAP (0x0304C023)

    Vi2 LCP: Event[Receive ConfReq-] State[ACKrcvd to ACKrcvd]

    Vi2 LCP: I CONFREQ [ACKrcvd] id 12 len 18

    Vi2 LCP:    MRU 1454 (0x010405AE)

    Vi2 LCP:    AuthProto PAP (0x0304C023)

    Vi2 LCP:    MagicNumber 0x3CC7AC81 (0x05063CC7AC81)

    Vi2 LCP: Sent too many CONFNAKs.  Switch to CONFREJ

    Vi2 LCP: O CONFREJ [ACKrcvd] id 12 len 8

    Vi2 LCP:    AuthProto PAP (0x0304C023)

    Vi2 LCP: Event[Receive ConfReq-] State[ACKrcvd to ACKrcvd]

    Vi2 LCP: I CONFREQ [ACKrcvd] id 13 len 18

    Vi2 LCP:    MRU 1454 (0x010405AE)

    Vi2 LCP:    AuthProto PAP (0x0304C023)

    Vi2 LCP:    MagicNumber 0x3CC7AC81 (0x05063CC7AC81)

    Vi2 LCP: Sent too many CONFNAKs.  Switch to CONFREJ

    Vi2 LCP: O CONFREJ [ACKrcvd] id 13 len 8

    Vi2 LCP:    AuthProto PAP (0x0304C023)

    Vi2 LCP: Event[Receive ConfReq-] State[ACKrcvd to ACKrcvd]

    Vi2 LCP: I CONFREQ [ACKrcvd] id 14 len 18

    Vi2 LCP:    MRU 1454 (0x010405AE)

    Vi2 LCP:    AuthProto PAP (0x0304C023)

    Vi2 LCP:    MagicNumber 0x3CC7AC81 (0x05063CC7AC81)

    Vi2 LCP: Sent too many CONFNAKs.  Switch to CONFREJ

    Vi2 LCP: O CONFREJ [ACKrcvd] id 14 len 8

    Vi2 LCP:    AuthProto PAP (0x0304C023)

    Vi2 LCP: Event[Receive ConfReq-] State[ACKrcvd to ACKrcvd]

    Vi2 LCP: I CONFREQ [ACKrcvd] id 15 len 18

    Vi2 LCP:    MRU 1454 (0x010405AE)

    Vi2 LCP:    AuthProto PAP (0x0304C023)

    Vi2 LCP:    MagicNumber 0x3CC7AC81 (0x05063CC7AC81)

    Vi2 LCP: Sent too many CONFNAKs.  Switch to CONFREJ

    Vi2 LCP: Sent too many CONFREJs.  Closing CP

    Vi2 PPP DISC: LCP failed to negotiate

    Vi2 PPP: Sending Acct Event[Down] id[66]

    PPP: NET STOP send to AAA.

    Vi2 LCP: O TERMREQ [ACKrcvd] id 2 len 4

    Vi2 LCP: Event[CLOSE] State[ACKrcvd to Closing]

    Vi2 LCP: I TERMACK [Closing] id 2 len 4

    Vi2 PPP: No remote authentication for call-out

    Vi2 LCP: Event[Receive TermAck] State[Closing to Closed]

    Vi2 LCP: Event[DOWN] State[Closed to Initial]

    Vi2 PPP: Phase is DOWN

    PPPoE : Shutting down client session

    [0]PPPoE 34721: O PADT  R:000b.4529.ec38 L:7081.05c1.7ec2 Gi0/2

    PPPoE: Failed to add PPPoE switching subblock

    %DIALER-6-UNBIND: Interface Vi2 unbound from profile Di1

    %LINK-3-UPDOWN: Interface Virtual-Access2, changed state to down

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

    5-3. Solutions

    From the results of 5-1 and 5-2, we verified that the authentication method seems to be PAP. However, even with the PAP or CHAP authentication setting, it was not possible to establish the connection as a result. In such cases, you can solve this in any of the following methods:

    1) Set the PAP authentication as the authentication method and set "ppp chap refuse" for Dialer Interface.

    If "ppp chap refuse" is set, CONFNAK will be returned to the LCP negotiation request (CONFREQ) in the CHAP authentication from the PPPoE server to reject this request. Shortly after that, the negotiation by the PAP authentication starts and you will be able to establish a session effectively.

    LCP in CHAP is being rejected

    Vi2 LCP: O CONFREQ [Starting] id 1 len 14

    Vi2 LCP:    MRU 1454 (0x010405AE)

    Vi2 LCP:    MagicNumber 0x8113B1CE (0x05068113B1CE)

    Vi2 LCP: Event[UP] State[Starting to REQsent]

    Vi2 LCP: I CONFACK [REQsent] id 1 len 14

    Vi2 LCP:    MRU 1454 (0x010405AE)

    Vi2 LCP:    MagicNumber 0x8113B1CE (0x05068113B1CE)

    Vi2 LCP: Event[Receive ConfAck] State[REQsent to ACKrcvd]

    Vi2 LCP: I CONFREQ [ACKrcvd] id 2 len 19

    Vi2 LCP:    MRU 1454 (0x010405AE)

    Vi2 LCP:    AuthProto CHAP (0x0305C22305)

    Vi2 LCP:    MagicNumber 0xB559B0FD (0x0506B559B0FD)

    Vi2 LCP: O CONFNAK [ACKrcvd] id 2 len 8

    Vi2 LCP:    AuthProto EAP (0x0304C227)

    Vi2 LCP: Event[Receive ConfReq-] State[ACKrcvd to ACKrcvd]

    Vi2 LCP: O CONFREQ [ACKrcvd] id 2 len 14

    Vi2 LCP:    MRU 1454 (0x010405AE)

    Vi2 LCP:    MagicNumber 0x8113B1CE (0x05068113B1CE)

    Vi2 LCP: Event[Timeout+] State[ACKrcvd to REQsent]

    Vi2 LCP: I CONFREQ [REQsent] id 3 len 18

    Vi2 LCP:    MRU 1454 (0x010405AE)

    Vi2 LCP:    AuthProto PAP (0x0304C023)

    Vi2 LCP:    MagicNumber 0xB559B0FD (0x0506B559B0FD)

    Vi2 LCP: O CONFACK [REQsent] id 3 len 18

    Vi2 LCP:    MRU 1454 (0x010405AE)

    Vi2 LCP:    AuthProto PAP (0x0304C023)

    Vi2 LCP:    MagicNumber 0xB559B0FD (0x0506B559B0FD)

    Vi2 LCP: Event[Receive ConfReq+] State[REQsent to ACKsent]

    Vi2 LCP: I CONFACK [ACKsent] id 2 len 14

    Vi2 LCP:    MRU 1454 (0x010405AE)

    Vi2 LCP:    MagicNumber 0x8113B1CE (0x05068113B1CE)

    Vi2 LCP: Event[Receive ConfAck] State[ACKsent to Open]

    2) Set both CHAP and PAP as the authentication method.

    If both CHAP and PAP are set, the process follows the same flow as 5-2. In 5-2, LCP negotiation failed in the PAP authentication after the CHAP authentication has failed. But with both authentication methods set, it is possible to return CONFACK to the LCP negotiation (CONFREQ) in the PAP authentication. Therefore, the LCP negotiation succeeds and the session can be established.

    Returning CONFACK to LCP negotiation (CONFREQ) in PAP authentication after CHAP authentication has failed

    Vi2 LCP: I CONFREQ [REQsent] id 1 len 18

    Vi2 LCP:    MRU 1454 (0x010405AE)

    Vi2 LCP:    AuthProto PAP (0x0304C023)

    Vi2 LCP:    MagicNumber 0x3CFDAC74 (0x05063CFDAC74)

    Vi2 LCP: O CONFACK [REQsent] id 1 len 18

    Vi2 LCP:    MRU 1454 (0x010405AE)

    Vi2 LCP:    AuthProto PAP (0x0304C023)

    Vi2 LCP:    MagicNumber 0x3CFDAC74 (0x05063CFDAC74)

    * Try using "ppp chap refuse" as well if you cannot establish the connection with only CHAP or PAP set.

    This is the end of the article.

    Related Information

    Original Document: https://supportforums.cisco.com/ja/document/93241
    Author: Katsunori Ishizuka
    Posted on February 28, 2012

    Troubleshooting for PPPoE Connection Failure - Part 1 -
    Troubleshooting for PPPoE Connection Failure - Part 2 -

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