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  Internet Protocol (IP/IPv4, IPng/IPv6) and IP-Related Protocols (IP NAT, IPSec, Mobile IP)
                9  Internet Protocol Mobility Support (Mobile IP)

Previous Topic/Section
Mobile IP Addressing: Home and "Care-Of" Addresses
Previous Page
Pages in Current Topic/Section
123
4
5
Next Page
Mobile IP Home Agent Registration and Registration Messages
Next Topic/Section

Mobile IP Agent Discovery, and Agent Advertisement and Solicitation Messages
(Page 4 of 5)

Mobility Agent Advertisement Extension

This is the main extension used to convey Mobile IP capabilities of the agent to mobile nodes on the local network. It contains numerous fields used as part of the various processes described in this overall section on Mobile IP.

The structure of the Mobility Agent Advertisement Extension is described in Table 81 and shown graphically in Figure 130.


Table 81: Mobile IP Mobility Agent Advertisement Extension Format

Field Name

Size (bytes)

Description

Type

1

Extension Type: Identifies the Agent Advertisement extension type. For the Mobility Agent Advertisement Extension, it is set to 16.

Length

1

Length: Length of the extension in bytes, excluding the Type and Length fields. Thus, it is equal to 6 plus 4 for each care-of address in the message.

Sequence Number

2

Sequence Number: A sequential counter set to zero when the router initializes and then incremented for each advertisement sent out.

Registration Lifetime

2

Registration Lifetime: The maximum length of time, in seconds, the agent is willing to accept for registration requests. A value of 65,535 (all ones) means “infinite”. Note that this field is for registration only and has no relation to the regular Lifetime field in the regular Router Advertisement part of the message.

Flags

1

 

Reserved

1

Reserved: Sent as zero and ignored by recipient.

Care-Of Addresses

Variable (4 per address)

Care-Of Addresses: Zero or more addresses provided by a foreign agent for a mobile node to use as a foreign agent care-of address. A foreign agent must always provide at least one address in its advertisement; a router that cannot act as a foreign agent will typically omit this field.



Figure 130: Mobile IP Mobility Agent Advertisement Extension Format

This extension appears after the normal fields of a Router Advertisement message, as shown in Figure 148.

 


Related Information: See the topic on Mobile IP encapsulation for more on minimal and GRE encapsulation and reverse tunneling.



Previous Topic/Section
Mobile IP Addressing: Home and "Care-Of" Addresses
Previous Page
Pages in Current Topic/Section
123
4
5
Next Page
Mobile IP Home Agent Registration and Registration 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.