Please Whitelist This Site?

I know everyone hates ads. But please understand that I am providing premium content for free that takes hundreds of hours of time to research and write. I don't want to go to a pay-only model like some sites, but when more and more people block ads, I end up working for free. And I have a family to support, just like you. :)

If you like The TCP/IP Guide, please consider the download version. It's priced very economically and you can read all of it in a convenient format without ads.

If you want to use this site for free, I'd be grateful if you could add the site to the whitelist for Adblock. To do so, just open the Adblock menu and select "Disable on tcpipguide.com". Or go to the Tools menu and select "Adblock Plus Preferences...". Then click "Add Filter..." at the bottom, and add this string: "@@||tcpipguide.com^$document". Then just click OK.

Thanks for your understanding!

Sincerely, Charles Kozierok
Author and Publisher, The TCP/IP Guide


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!

Get The TCP/IP Guide for your own computer.
The TCP/IP Guide

Custom Search







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 Internet Layer (OSI Network Layer) Protocols
           9  TCP/IP Routing Protocols (Gateway Protocols)
                9  TCP/IP Exterior Gateway/Routing Protocols (BGP and EGP)
                     9  TCP/IP Border Gateway Protocol (BGP/BGP-4)
                          9  BGP Detailed Messaging, Operation and Message Formats

Previous Topic/Section
BGP Message Generation and Transport, and General Message Format
Previous Page
Pages in Current Topic/Section
1
2
Next Page
BGP Route Information Exchange: Update Messages
Next Topic/Section

BGP Connection Establishment: Open Messages
(Page 1 of 2)

Before a BGP session can be used to exchange routing information, a connection must first be established between BGP peers. This process begins with the creation of a TCP connection between the devices. Once this is done, the BGP devices will attempt to create a BGP session by exchanging BGP Open messages.

The Open message has two main purposes. The first is identification and initiation of a link between the two devices; it allows one peer to tell the other “I am a BGP speaker named X on autonomous system Y, and I want to start exchanging BGP information with you”. The second is negotiation of session parameters. These are the terms by which the BGP session will be conducted. One important parameter negotiated using Open messages is the method that each device wants to use for authentication. The importance of BGP means that authentication is essential, to avoid bad information or a malicious person from disrupting routes.

Each BGP receiving an Open message processes it. If its contents are acceptable, including the parameters the other device wants to use, it responds with a Keepalive message as an acknowledgment. Each peer must send an Open and receive a Keepalive acknowledgment for the BGP link to be initialized. If either is not willing to accept the terms of the Open, the link is not established. In that case, a Notification message may be sent to convey the nature of the problem.


Previous Topic/Section
BGP Message Generation and Transport, and General Message Format
Previous Page
Pages in Current Topic/Section
1
2
Next Page
BGP Route Information Exchange: Update Messages
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.