Mobile IPv6 A.01.00 Administrator's Guide

Chapter 1

Introducing HP-UX Mobile IPv6

Establishing Basic Operation

In most cases, the Mobile Node and Correspondent Node communicate using Route Optimization. Mobile

IPv6 basic operation is used in initial communication, when the Correspondent Node does not have

information about the Mobile Node’s Care-of Address, and in cases where the Correspondent Node does not

support Mobile IPv6 Route Optimization. In some topologies, forcing Mobile Nodes to use basic operation also

provides more security.

The following is the procedure for establishing Mobile IPv6 basic operation:

1. The Mobile Node detects it is attached to a new network (movement detection).

2. The Mobile Node acquires a Care-of Address on the foreign network.

3. The Mobile Node sends a Binding Update to its Home Agent. The Binding Update contains the Mobile

Node’s Care-of Address and Home Address.

4. The Home Agent sends Neighbor Advertisements to bind its link-level address with the Mobile Node’s

home address. This allows the Home Agent to capture IPv6 data-packets addressed to the Mobile Node’s

home address.

Movement Detection

Mobile Nodes use IPv6 Router Advertisement and Neighbor Discovery methods to detect when they have

moved to or attached to a new network (also referred to as movement detection). For example, if a Mobile

Node receives a Router Advertisement with a different network preﬁx than its current preﬁx, the Mobile

Node can assume it has moved to a new network. A Mobile Node should also determine when its current

default router is still reachable, and can use IPv6 Neighbor Unreachability Detection. A Mobile Node might

also actively send Router Solicitation messages to solicit Router Advertisement messages, to determine if the

current default router is still reachable, or to ﬁnd a new default router.

The following is a list of events shown in Figure 1-5, Movement Detection, that a Mobile Node can use to

determine it has attached to a new network:

1. A Mobile Node travels into a foreign network

2. The Mobile Node sends a Router Solicitation Message

3. A router on the foreign network responds with a Router Advertisement that includes the network preﬁx

of the foreign network

4. The Mobile Node uses information in the Router Advertisement message to determine it is away from its

home link, and to generate a Care-of Address

5. The Mobile Node sends a Binding Update message to its Home Agent on its home link

NOTE After receiving the Binding Update, the Home Agent might send a Binding Acknowledgement

to the Mobile Node to acknowledge the Binding Update and to indicate whether it was accepted

or rejected. The Home Agent will send a Binding Acknowledgement if the Mobile Node sets the

A-bit in its Binding Update.