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© 2008 Cisco Systems, Inc. All rights reserved. IUWNE v1.0—2-1 Basic Cisco WLAN Installation Roaming

Iuwne10 S02 L05

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  • 1. Basic Cisco WLAN Installation Roaming

2. Mobility Groups, Mobility Domains 3. Controller > General A Cisco Wireless LAN Controller (WLC) can only reside in a single mobility group . 4. Controller > Mobility Management > Mobility Groups There are two methods to define the mobility group: Add a member using either the New or Edit All option, in which all members are represented in a text format. A controller can know members of other mobility groups. 5. Roaming Concept

    • Roaming refers to movement of clients across Cisco APs while transmitting
    • Roaming can occur across different mobility groups, but must be within a mobility domain
    • The Cisco WLC can reside in only a single mobility group
    • The following should be consistent for mobility groups:
      • Mobility group membership
      • Code across all member controllers
      • LWAPP mode across all member controllers
      • ACLs configured on all member controllers
      • WLAN configuration
      • Virtual IP address
    • Two types of roaming
      • Intrasubnet roaming (Layer 2)
      • Intersubnet roaming (Layer 3)

6. Cisco Wireless Layer 2 Roaming

    • Single Cisco WLC
    • Multiple Cisco WLCs in the same subnetwork
    • Transparent to the client
    • The session is sustained during connection to the new AP
    • The client continues using the same DHCP-assigned or static IP address

7. Client Roaming Within a Subnetwork 8. Cisco Wireless Layer 3 Roaming

    • Multiple Cisco WLCs in different subnetworks
    • Transparent to the client
    • The session is sustained during connection to the new AP
    • Tunnel between the anchor Cisco WLC and foreign Cisco WLC along with special handling of the client traffic by both controllers allows the client to continue using the same DHCP or client-assigned IP address while the session remains active
    • Set up via either a symmetric or asymmetric tunnel

9. Client Roaming Across Subnetworks 10. Roaming Example Preroaming 11. Roaming Example Layer 3 Asymmetric 12. Roaming Example Layer 3 Asymmetric (Cont.) 13. Roaming Example Layer 3 Symmetric 14. Roaming Example Layer 3 Symmetric (Cont.) 15. Symmetric or Asymmetric Tunnelling 16. Roaming: Tunnels (Symmetric Example) 17. Cisco Wireless Mobility Anchor 18. Cisco Wireless Mobility Anchor Considerations

    • A foreign session to the anchor is set up ahead of client IP address determination.
      • The foreign controller will have no knowledge of Layer 3 client information.
    • Web authentication is supported, but authentication will occur on the mobility anchor as opposed to the local controller.
    • This mobility anchor function is only available on Cisco 4400 Series Wireless LAN Controllers and Cisco WiSM blades.
      • 2100/WLCM can be foreign controller, but not anchor the guest tunnel.

19. WLANs > Mobility Anchors 20. Controller > Mobility Management > Mobility Anchor Config 21. Summary

    • Controllers can be part of the same mobility group, which allows them to exchange information about clients.
    • Roaming occurs when a stations changes connection point while transmitting.
    • At Layer 2, credentials are passed from one controller to the other to ensure seamless mobility.
    • At Layer 3, roaming can be symmetric or asymmetric, to maintain the client IP address or complete connection to the original subnet.
    • When roaming is asymmetric, the mobility anchor feature allows a partial symmetric configuration based on the WLAN.