Concept Guide

339 | Mobility and Client Management Dell Networking W-Series Instant 6.5.1.0-4.3.1.0 | User Guide
When a client first connects to an Instant network, a message is sent to all configured VC IP addresses to see if
this is an L3 roamed client. On receiving an acknowledgement from any of the configured VC IP addresses, the
client is identified as an L3 roamed client. If the W-IAP has no GRE tunnel to this home network, a new tunnel is
formed to an W-IAP (home W-IAP) from the client's home network.
Each foreign W-IAP has only one home W-IAP per Instant network to avoid duplication of broadcast traffic.
Separate GRE tunnels are created for each foreign W-IAP-home W-IAP pair. If a peer W-IAP is a foreign W-IAP
for one client and a home W-IAP for another, two separate GRE tunnels are used to handle L3 roaming traffic
between these W-IAPs.
If client subnet discovery fails on association due to some reason, the foreign W-IAP identifies its subnet when
it sends out the first L3 packet. If the subnet is not a local subnet and belongs to another Instant network, the
client is treated as an L3 roamed client and all its traffic is forwarded to the home network through a GRE
tunnel.
Configuring L3-Mobility
To configure a mobility domain, you have to specify the list of all Instant networks that form the mobility
domain. To allow clients to roam seamlessly among all the W-IAPs, specify the VC IP for each foreign subnet.
You may include the local Instant or VC IP address, so that the same configuration can be used across all
Instant networks in the mobility domain.
It is recommended that you configure all client subnets in the mobility domain.
When the client subnets are configured, note the following scenarios:
l If a client is from a local subnet, it is identified as a local client. When a local client starts using the IP address,
L3 roaming is terminated.
l If the client is from a foreign subnet, it is identified as a foreign client. When a foreign client starts using the
IP address, L3 roaming is set up.
Home Agent Load Balancing
Home Agent Load Balancing is required in large networks where multiple tunnels might terminate on a single
border or lobby W-IAP and overload it. When load balancing is enabled, the VC assigns the home W-IAP for
roamed clients by applying a round robin policy. With this policy, the load for the W-IAPs acting as Home Agents
for roamed clients is uniformly distributed across the W-IAP cluster.
Configuring a Mobility Domain for Instant
You can configure L3 mobility domain by using the Instant UI or the CLI.
In the Instant UI
To configure a mobility domain:
1. Click the System link on the Instant main window.
2. In the Services section, click the Show advanced options link. The advanced options are displayed.
3. Click L3 Mobility. The L3 Mobility window is displayed.