NOTE: Using software to mass-download the site degrades the server and is prohibited.
If you want to read The TCP/IP Guide offline, please consider licensing it. Thank you.

The Book is Here... and Now On Sale!

Read offline with no ads or diagram watermarks!
The TCP/IP Guide

Google
Web TCP/IP Guide






Table Of Contents  The TCP/IP Guide
 9  TCP/IP Lower-Layer (Interface, Internet and Transport) Protocols (OSI Layers 2, 3 and 4)
      9  TCP/IP Network Interface Layer (OSI Data Link Layer) Protocols
           9  TCP/IP Serial Line Internet Protocol (SLIP) and Point-to-Point Protocol (PPP)
                9  Point-to-Point Protocol (PPP)
                     9  PPP Fundamentals and Operation

Previous Topic/Section
PPP Components and General Operation
Previous Page
Pages in Current Topic/Section
12
3
Next Page
 PPP Standards
Next Topic/Section

PPP Link Setup and Phases
(Page 3 of 3)

Differentiating LCP and NCP Links

Remember that the basic link is established by LCP, and NCP links are set up within the LCP link. Closing an NCP link does not cause the LCP link to be closed. Even if all NCPs are closed, the LCP link remains open. (Of course, no data can be passed until an appropriate NCP link is re-established; a device is required to discard frames received containing any layer three protocol that does not have an opened NCP.) To terminate a PPP connection, only the LCP link needs to be terminated in the Link Termination phase; the NCPs do not need to be explicitly closed.

PPP Link Setup and Phase Summary

A summary of PPP phases can be found in Table 24. In the table, the LCP Link Status and NCP Link Status columns show the status of the link as the phase starts.


Table 24: PPP Phases

Phase/
State

Phase Summary

LCP Link Status Upon Entry To Phase

NCP Link Status Upon Entry To Phase

Transition Requirement

Transition To Phase

Link Dead

Default state; physical layer not connected.

Closed

Closed

Successful
physical layer connection

Link Establishment

Link Establishment

Physical layer connected, basic configuration of link performed by LCP.

Closed

Closed

Successful
negotiation

Authentication

Unsuccessful negotiation

Link Dead

Authentication

Basic link is now opened, and optional authentication of device is performed.

Open

Closed

Successful authentication or no authentication required

Network-Layer Protocol

Unsuccessful authentication

Link Termination

Network-Layer Protocol

One or more NCPs open an NCP link within the LCP link.

Open

Closed

All NCPs opened

Link Open

Link Open

Link is open and operating normally.

Open

Open

Link failure or close request

Link Termination

Link Termination

LCP link is shut down.

Open

Open

 

Link Dead

Previous Topic/Section
PPP Components and General Operation
Previous Page
Pages in Current Topic/Section
12
3
Next Page
 PPP Standards
Next Topic/Section

If you find The TCP/IP Guide useful, please consider making a small Paypal donation to help the site, using one of the buttons below. You can also donate a custom amount using the far right button (not less than $1 please, or PayPal gets most/all of your money!) In lieu of a larger donation, you may wish to consider purchasing a download license of The TCP/IP Guide. Thanks for your support!
Donate $2
Donate $5
Donate $10
Donate $20
Donate $30
Donate: $


Home - Table Of Contents - Contact Us

The TCP/IP Guide (http://www.TCPIPGuide.com)
Version 3.0 - Version Date: September 20, 2005

© Copyright 2001-2005 Charles M. Kozierok. All Rights Reserved.
Not responsible for any loss resulting from the use of this site.