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!

Read offline with no ads or diagram watermarks!
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  Internet Control Message Protocol (ICMP/ICMPv4 and ICMPv6)
                9  ICMP Message Types and Formats
                     9  ICMP Version 4 (ICMPv4) Informational Message Types and Formats

Previous Topic/Section
ICMPv4 Timestamp (Request) and Timestamp Reply Messages
Previous Page
Pages in Current Topic/Section
1
2
34
Next Page
ICMPv4 Address Mask Request and Reply Messages
Next Topic/Section

ICMPv4 Router Advertisement and Router Solicitation Messages
(Page 2 of 4)

ICMPv4 Router Advertisement Message Format

The ICMPv4 Router Advertisement message format is shown in Table 98 and Figure 148.


Table 98: ICMPv4 Router Advertisement Message Format

Field Name

Size (bytes)

Description

Type

1

Type: Identifies the ICMP message type. For Router Advertisement messages the value is 9.

Code

1

Code: Normally set to 0. When a Mobile IP agent is sending a Router Advertisement with an Agent Advertisement extension, it may set the value to 16 if the device is a mobile agent only and doesn’t intend to handle normal traffic. See the discussion of Mobile IP agent discovery for details.

Checksum

2

Checksum: 16-bit checksum field for the ICMP header, as described in the topic on the ICMP common message format.

Num Addrs

1

Number Of Addresses: The number of addresses associated with this router that are included in this advertisement.

Addr Entry Size

1

Address Entry Size: The number of 32-bit words of information included with each address. Since in this message format each router address has a 32-bit address and a 32-bit preference level, this value is fixed at 2.

Lifetime

2

Lifetime: The number of seconds that a host should consider the information in this message valid.

Router Address Entries

Value of Num Addrs field * 8

 



Figure 148: ICMPv4 Router Advertisement Message Format

 


Previous Topic/Section
ICMPv4 Timestamp (Request) and Timestamp Reply Messages
Previous Page
Pages in Current Topic/Section
1
2
34
Next Page
ICMPv4 Address Mask Request and Reply 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.