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!

Enjoy The TCP/IP Guide? Get the complete PDF!
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 Interior Routing Protocols (RIP, OSPF, GGP, HELLO, IGRP, EIGRP)
                     9  Open Shortest Path First (OSPF)

Previous Topic/Section
OSPF General Operation and Message Types
Previous Page
Pages in Current Topic/Section
12
3
4567
Next Page
Other Interior Routing Protocols
Next Topic/Section

OSPF Message Formats
(Page 3 of 7)

Database Description Message Format

These messages have a Type value of 2 in the header, and the body structure depicted in Table 128 and Figure 186.


Table 128: OSPF Database Description Message Format

Field Name

Size (bytes)

Description

Interface MTU

2

Interface MTU: The size of the largest IP message that can be sent on this router's interface without fragmentation.

Options

1

Options: Indicates which of several optional OSPF capabilities the router supports.

Flags

1

 

DD Sequence Number

4

DD Sequence Number: Used to number a sequence of Database Description messages so they are kept in order.

LSA Headers

Variable

LSA Headers: Contains link-state advertisement headers, which carry information about the LSDB. See near the end of the topic for more information on LSAs.



Figure 186: OSPF Database Description Message Format

 


Previous Topic/Section
OSPF General Operation and Message Types
Previous Page
Pages in Current Topic/Section
12
3
4567
Next Page
Other Interior Routing Protocols
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.