PPP Debugging Smooths Remote Access

PPP Messages Decoded
Conf-Req contains requested configuration options. The Conf-Req should only contain options that are nonstandard, and as LCP converges, the number of options in the packets may be lower than the initial request. PPP peers respond to Conf-Req with Conf-Ack, Conf-Nak or Conf-Rej.

Conf-Ack OKs the options that are listed in the packet. Both peers must successfully acknowledge the peers' requests to establish PPP.

Conf-Nak contains options that the peer can negotiate, but with parameters that are not satisfactory, such as IP address negotiation in IPCP. The options in the PPP packets also contain suggested parameters by the sender of the Conf-Nak. Peers inform each other of acceptable configuration parameters using a series of Conf-Req and Conf-Naks.

Conf-Rej contains options that the peer cannot negotiate. Typical options are call-back and Multilink PPP. Options that are rejected should be dropped from further Conf-Req. If one peer requires an option the other side can't negotiate, the LCP won't converge and the link will drop.



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