Introducing HP-UX Mobile IPv6

2.2 HP-UX Mobile IPv6 Product Functionality

HP-UX Mobile IPv6 includes a kernel-resident STREAMS module that processes and generates

Mobility Headers, delivering the following functionality for HP-UX 11i version 1 and 2 servers:

• Home Agent functionality

• Correspondent Node functionality

The primary function of the Home Agent is to provide mobility services to Mobile Nodes in their Home

Networks. The primary function of Correspondent Nodes is providing Route Optimization support on

IPv6 systems that communicate with Mobile Nodes. In most cases, the Mobile Node and

Correspondent Node communicate using Route Optimization. Mobile IPv6 basic operation is used in

the 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.

2.2.1 Home Agents

Home Agents are nodes or routers that provide mobility services to Mobile Nodes from their home

network. The primary role of the Home Agent is visible during Mobile IPv6 basic operation—when a

Mobile Node is away from its Home Network and the Home Agent intercepts data packets sent to the

Mobile Node’s home address and routes them to the Mobile Node’s current Care-of Address as shown

in the following figure:

Foreign Network

Home Network

Home Agent

Mobile Node

Correspondent

Node

When a Mobile Node sends data packets to Correspondent Nodes during basic operation, the Home

Agent forwards the data packet from the Mobile Node to the Correspondent Node, a concept in Mobile

IPv4 known as “reverse tunneling.”

2.2.2 Correspondent Nodes

Correspondent Nodes are HP-UX IPv6 servers communicating or corresponding with the Mobile

Nodes—usually with route optimization. A web server providing location-sensitive resources to Mobile

Nodes is an example of typical Correspondent Node deployment.

2.2.3 Utilizing the HP-UX IPv6 Router Advertisiement Daemon

In addition to the Home Agent and Correspondent Node functionality provided by HP-UX Mobile IPv6,

TOUR 2.0 delivers the HP-UX IPv6 Router Advertisement Daemon, or rtradvd. HP-UX Mobile IPv6

depends-on and utilizes the rtradvd to perform the following mobility functions on HP-UX IPv6

systems:

• configures the system as a Home Agent

• generates and processes Router Advertisement messages

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 assumes it has moved to a new network.