Vidar Stokke

1. Controller based wireless networks • Vidar Stokke • Senior Engineer at the Norwegian University of Science and Technology, IT-division, Networking • Programme: • History of wireless networks at NTNU • The wireless network with standalone APs • The wireless network with controller based APs • Pros and cons of controller based networks

2. History of WLAN at NTNU • 2004/2005: 250 autonomous APs (802.11b og g) • Hotspot coverage • public areas and meeting rooms • Approx 20% coverage • Authentication by web portal (HP) and/or VPN (Cisco) • Challenges: • Time consuming administration • No mobility • Capasity issues due to many users on few AP • Web portal did not scale • 1100-1200 associated clients

3. The ”Wireless Campus” project – with lightweight APs • The goal was ”100%” wireless coverage in NTNU’s buildings. • Started Q3 2006 and terminated Q3 2008 • The process: • Site survey (External company) • Wiring and AP mounting (3 different electrical contractors) • PoE-switch installation in wiring cabinets (NTNU IT) • Resulted in approx 1400 APs, 18 wireless controllers and 100 PoE switches

4. The ”Wireless Campus” project – with lightweight APs • In 2011: • 1800 APs • 20 controllers • 10.000 simultaneous clients at peak hours • Approximately 300.000 sqm coverage • Deployment of controller based wireless network was a success

5. A comparison of standalone and lightweight/controller based wireless • Standalone • Everything on and through the AP • Traditional lightweight • Everything on and through the controller • Hybrid lightweight • Almost everything on and through the controller, but with a certain flexibility

6. Wireless with standalone APs

7. Wireless with lightweigh APs

8. Wireless with lightweight APs and H-REAP

9. AP join process - discovery • Ways to discover controllers • Layer 2 broadcast on local subnet • List of previously known controllers • OTAP (Over The Air Provisioning) – removed from Ciscos SW • DHCP option 43 • DNS lookup for ”cisco-capwap-controllers.domain”

10. AP join process - CAPWAP

11. Mobility groups • Several controllers can join one mobility group • Client roaming across different controllers and APs • Without loosing connection • Without the need to reauthenticate

12. Mobility groups

13. Auto-RF • Each controller is part of an RF network • APs connected will forward RRM-info to its controller about other APs it sees. • Adjusts channel and power assignment based on leaders computations • One controller is the leader of the RF domain • Collects necessary RRM-info from other controllers • Tries to avoid neighbour APs on same channel and interference • Calculates and computes the best possible channel and power assignment for the different APs

14. Rogue detection and containment • APs not within the RF-domain is marked as rogue • Possible to do a joint effort to take them down • Up to 4 APs join together • Send diassociation messages to the connected clients

15. Downsides with lightweight • Get stuck with one brand (ie. Cisco) • Even though CAPWAP opens for third-party components • Harder to do hardware upgrades on APs and/or controller • Controller and APs need to support each other • Expensive with a low number of APs

16. Benefits of lightweight solution • Easier management/configuration of a large number of APs: • All configuration done at controller and pushed to APs • Major changes done by the click of a button • Software upgrade done from controllers and deployed to APs • PlugNPlay of new APs and replacement APs • Radio Resource Management (RRM) • Auto-RF • Client load balancing

17. Benefits of lightweight solution • Better mobility for clients • Due to mobility groups • Improved overview of the wireless network • Client information and debugging • AP statistics • AP and client alarms • Location based services (requires WCS) • NTNU Campusguiden

18. A demo?

19. Questions?