HP-UX Mobile IPv6 A.01.00 Administrator's Guide

Chapter 1

Introducing HP-UX Mobile IPv6

Establishing Route Optimization

Route Optimization improves data transmission rates between the Correspondent Node and Mobile Node.

Without Route Optimization, data-packets from the Correspondent Node to the Mobile Node are sent to the

Home Agent (and through the Mobile Node’s home network). With Route Optimization, the Correspondent

Node sends data-packets directly to the Mobile Node’s Care-of Address.

To establish Route Optimization, the Mobile Node sends a Binding Update message to the Correspondent

Node with its current Care-of Address. To prevent attackers from sending false Binding Update messages, the

Binding Update is authenticated using a cryptographic signature that verifies the Correspondent Node can

contact the Mobile Node using both its Home Address and Care-of Address. Verifying that the Correspondent

Node can contact the Mobile Node using both addresses is referred to as the Return Routability procedure.

Most Mobile Nodes will attempt to use Route Optimization after they receive a data-packet from a

Correspondent Node through the Home Agent, which indicates the Correspondent Node does not have

binding information with the Mobile Node’s current Care-of Address.

The following list describes the sequence of events shown in Figure 1-8, Return Routability Procedure for

Securing Route Optimization. After the Mobile Node acquires a Care-of Address:

1. The Mobile Node sends a Care-of Test Init message and a Home Test Init message to the Correspondent

Node.

2. The Correspondent Node sends Care-of Test and Home Test responses to the Mobile Node.

3. The Mobile Node calculates a Binding Management Key (Kbm) from the Care-of Test and Home Test

messages.

4. The Mobile Node sends an authenticated Binding Update message to the Correspondent Node with its

Care-of Address.

5. The Correspondent Node verifies the Binding Update message and sends a Binding Acknowledgement.

NOTE After receiving the Binding Update, the Correspondent Node might send a Binding

Acknowledgement to the Mobile Node to acknowledge the Binding Update and to indicate

whether it was accepted or rejected. The Correspondent Node will send a Binding

Acknowledgement if the Mobile Node sets the A-bit in its Binding Update.