Command:

debug ppp


Mode:

Router#

Syntax:

debug ppp {packet | negotiation | error | authentication | compression | cbcp}

no debug ppp {packet | negotiation | error | authentication | compression | cbcp}

Syntax Description:

packet

Displays PPP packets being sent and received. (This command displays low-level packet dumps.)

negotiation

Displays PPP packets transmitted during PPP startup, where PPP options are negotiated.

error

Displays protocol errors and error statistics associated with PPP connection negotiation and operation.

authentication

Displays authentication protocol messages, including Challenge Authentication Protocol (CHAP) packet exchanges and Password Authentication Protocol (PAP) exchanges.

compression

Displays information specific to the exchange of PPP connections using MPPC. This command is useful for obtaining incorrect packet sequence number information where MPPC compression is enabled.

cbcp

Displays protocol errors and statistics associated with PPP connection negotiations using MSCB.


Command Description:

Use the debug ppp EXEC command to display information on traffic and exchanges in an internetwork implementing the Point-to-Point Protocol (PPP).

Example:

Router#debug ppp negotiation

The following is sample output from the debug ppp negotiation command. This is a normal
negotiation, where both sides agree on network control program (NCP) parameters. In this
case, protocol type IP is proposed and acknowledged.

ppp: sending CONFREQ, type = 4 (CI_QUALITYTYPE), value = C025/3E8
ppp: sending CONFREQ, type = 5 (CI_MAGICNUMBER), value = 3D56CAC
ppp: received config for type = 4 (QUALITYTYPE) acked
ppp: received config for type = 5 (MAGICNUMBER) value = 3D567F8 acked (ok)
PPP Serial4: state = ACKSENT fsm_rconfack(C021): rcvd id 5
ppp: config ACK received, type = 4 (CI_QUALITYTYPE), value = C025
ppp: config ACK received, type = 5 (CI_MAGICNUMBER), value = 3D56CAC
ppp: ipcp_reqci: returning CONFACK.
 (ok)
PPP Serial4: state = ACKSENT fsm_rconfack(8021): rcvd id 4
Misconceptions:
None

Related Commands:
debug all

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