Users Guide

Dell Networking W-Series ArubaOS 6.4.x| User Guide IP Mobility | 689
Chapter 28
IP Mobility
A mobility domain is a group of Dell controllers among which wireless users can roam without losing their IP
address. Mobility domains are not tied with the master controller; thus, it is possible for a user to roam
between controllers managed by different master controllers, as long as all the controllers belong to the same
mobility domain.
You enable and configure mobility domains only on Dell controllers. No additional software or configuration is
required on wireless clients to allow roaming within the domain.
Topics in this chapter include:
l Understanding Dell Mobility Architecture on page 689
l Configuring Mobility Domains on page 690
l Tracking Mobile Users on page 694
l Configuring Advanced Mobility Functions on page 696
l Understanding Bridge Mode Mobility Deployments on page 705
l Enabling Mobility Multicast on page 706
Understanding Dell Mobility Architecture
Dell’s layer-3 mobility solution is based on the Mobile IP protocol standard, as described in RFC 3344, IP
Mobility Support for IPv4. This standard addresses users who need both network connectivity and mobility
within the work environment.
Unlike other layer-3 mobility solutions, a Dell mobility solution does not require that you install mobility
software or perform additional configuration on wireless clients. The Dellcontrollers perform all functions that
enable clients to roam within the mobility domain.
In a mobility domain, a mobile client is a wireless client that can change its point of attachment from one
network to another within the domain. A mobile client receives an IP address (a home address) on a home
network.
A mobile client can detach at any time from its home network and reconnect to a foreign network (any network
other than the mobile client’s home network) within the mobility domain. When a mobile client is connected to
a foreign network, it is bound to a care-of address that reflects its current point of attachment. A care-of
address is the IP address of the Dell controller in the foreign network with which the mobile client is associated.
The home agent for the client is the controller at which the client appears for the first time upon joining the
mobility domain. The home agent is the single point of contact for the client when the client roams. The foreign
agent for the client is the controller which handles all Mobile IP communication with the home agent on behalf
of the client. Traffic sent to a client’s home address is intercepted by the home agent and tunneled for delivery
to the client on the foreign network. On the foreign network, the foreign agent delivers the tunneled data to
the mobile client.
Figure 86 shows the routing of traffic from Host A to Mobile Client B when the client is away from its home
network. The client’s care-of address is the IP address of the Dell controller in the foreign network.
The numbers in the Figure 86 correspond to the following descriptions:
1. Traffic to Mobile Client B arrives at the client’s home network via standard IP routing mechanisms.
2. The traffic is intercepted by the home agent in the client’s home network and tunneled to the care-of
address in the foreign network.