Cisco 4400 Series Wireless LAN Controllers

This document provides information on the most frequently asked questions (FAQ) about Mobility Groups. A Mobility Group is a relatively new concept that is applicable to the Cisco Unified Wireless LAN Environment.

A. These are some of the prerequisites that are necessary in order for the Wireless LAN Controllers (WLCs) to be in a Mobility Group:

• All WLCs must be configured for the same LWAPP transport mode (Layer 2 or Layer 3).

• IP connectivity must exist between the management interfaces of all devices.

• All WLCs must be configured with the same Mobility Group name.

• All WLCs must be configured with the same virtual interface IP address.

• Each WLC must be configured with the MAC and IP addresses of the other WLCs to be included in the Mobility Group.

  Note: More stability is observed when the WLCs in the same Mobility Group have the same software version.

A. No. Wireless LAN Controllers (WLCs) can be configured only in one Mobility Group.

A. A mobility list is a group of controllers configured on a single controller that specifies members in different mobility groups. In the example in this section, controller 1 can communicate with either controller 2 or 3, but controller 2 and controller 3 can communicate only with controller 1 and not with each other. Similarly, clients can roam between controller 1 and controller 2 or between controller 1 and controller 3 but not between controller 2 and controller 3.

Example:
Controller 1                   Controller 2                    Controller 3
Mobility group: A              Mobility group: B               Mobility group: C
Mobility list:                 Mobility list:                  Mobility list:
     Controller 1 (group A)          Controller 1 (group A)          Controller 1 (group A)
     Controller 2 (group B)          Controller 2 (group B)          Controller 3 (group C)
     Controller 3 (group C)

Controller software release 5.1 supports up to 72 controllers in the mobility list of a controller and seamless roaming across multiple mobility groups. During seamless roaming, the client maintains its IP address across all mobility groups. However, Cisco Centralized Key Management (CCKM) and Proactive Key Caching (PKC) are supported only for intra-mobility-group roaming. When a client crosses a mobility group boundary during a roam, the client is fully authenticated, but the IP address is maintained, and EtherIP tunneling is initiated for Layer 3 roaming.

Note: Controller software release 5.0 supports up to 48 controllers in a mobility list.

A. In order to secure the Mobility Messages exchanged between the Wireless LAN Controllers (WLCs), enable the Secure mode between the controllers. In order to do this, issue the config mobility secure-mode enable command. In this mode, WLCs use the UDP port 16667 in order to exchange the messages. If there is a firewall, ensure that the UDP port 16667 is opened. In order to ensure this mode is enabled, verify the Mobility Protocol Port from the output of the show mobility summary command. Port 16667 indicates secure-mode (encryption). Port 16666 indicates non secure-mode (no encryption).

A. WLCs use EoIP protocol over UDP port 97 in order to transport data packets and UDP port 16666 in order to exchange control packets. Make sure that ports 97 and 16666 are opened on the firewall. You can also run mobility ping tests in order to check the connectivity.