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DellPowerConnectW-SeriesArubaOS6.2 | User Guide IPMobility | 492
Chapter 28
IP Mobility
A
mobility domain
is a group of Dell controllers among which a wireless user 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 Dell
controllers managed by different master Dell controllers as long as all of the Dell 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 492
l "Configuring Mobility Domains" on page 493
l "Tracking Mobile Users" on page 497
l "Configuring Advanced Mobility Functions" on page 499
l "Understanding Bridge Mode Mobility Deployments" on page 503
l "Enabling Mobility Multicast" on page 504
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 where the client appears for the first time when it joins 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 150 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 150 correspond to the following descriptions:
1. Traffic to Mobile Client B arrives at the client’s home network via standard IP routing mechanisms.