18. Wireless Infrastructure Flashcards
What are the 2 modes a Cisco AP can operate in?
- Autonomous
- Lighweight
What is the difference between the 2 Cisco AP modes?
The autonomous is self-sufficient and standalone
The lightweight need something bigger to operate
What does a autonomus AP need?
A own IP address
What does a lightweighted AP need to become functional?
A WLC
What is a split-MAC architecture?
Where the AP handles the realtime 802.11 processes and the WLC the management functions
What is transported through CAPWAP tunnels?
Data and control traffic between AP and WLC
What is a centralized or unified wlan topology?
When the WLC is placed in a central location, usually the data center or near the network core
Why is the maximum delay for the RTT between an AP and WLC?
100 ms
What is a embedded wlan topology?
When the WLC is embedded in the access layer switch
How many APs does a Cisco embedded WLC support?
200
What is the disadvantage of a embedded topology?
Traffic destined to a central location will be decapsulated at the access layer.
What is a mobility express wlan topology?
Where the WLC software runs on a AP
How many APs does a Cisco mobility express WLC support?
100
How is the sequence of CAPWAP states called?
State machine
What are 8 most common CAPWAP states of an AP?
- AP boots (done with a small IOS image)
- WLC discovery
- CAPWAP tunnel
- WLC join
- Download image
- Download config
- Run state
- Reset
What happens in the WLC join state?
AP selects a WLC from the candidate list and sends a CAPWAP join request.
WLC replies with a CAPWAP Join Reponse
What happens in the Download image state?
The WLC informs the AP of its software release
If not equal, the AP downloads an image of the WLC, reboots and starts at step 1 again
What happens in the Download config state?
AP pulls config parameters from the WLC and updates values as RF, SSID, security and QoS
What happens in the Run state state?
Once AP is full initialized the WLC places it in the run state. WLC and AP begin providing a BSS and accept clients
What can be done to prevent AP downtime due to OS updates?
Newer software can be downloaded on the WLC, but not rebooted. This gives the APs time to download it first as well