User's Manual

3/11/05 Layer 2 and Layer 3 LWAPP Operation
OL-7426-02
For information about Cisco SWAN wireless security, refer to Operating System Security.
Layer 2 and Layer 3 LWAPP OperationLayer 2 and Layer 3 LWAPP Operation
The LWAPP communications between Cisco Wireless LAN Controllers and Cisco 1000 Series lightweight
access points can be conducted at ISO Data Link Layer 2 or Network Layer 3, when the connections are
made in Appliance Mode
.
Operational RequirementsOperational Requirements
The requirement for Layer 2 LWAPP communications is that the Cisco Wireless LAN Controllers and
Cisco 1000 Series lightweight access points must be connected through Layer 2 devices on the same
subnet. This is the default operational mode for the Cisco SWAN. Note that when the Cisco Wireless
LAN Controller and Cisco 1000 Series lightweight access points are on different subnets, these devices
must be operated in Layer 3 mode.
The requirement for Layer 3 LWAPP communications is that the Cisco Wireless LAN Controllers and
Cisco 1000 Series lightweight access points can be connected directly to each other, connected through
Layer 2 devices on the same subnet, or connected through Layer 3 devices across subnets.
Note that all Cisco Wireless LAN Controllers in an Controller Mobility Group
must use the same LWAPP
Layer 2 or Layer 3 mode, or you will defeat the Mobility software algorithm.
Configuration RequirementsConfiguration Requirements
When you are operating the Cisco SWAN in Layer 2 mode, you must configure a Management Interface
to control your Layer 2 communications.
When you are operating the Cisco SWAN in Layer 3 mode, you must configure a Management Interface
to control your Layer 2 communications, and an AP-Manager Interface to control Cisco 1000 Series
lightweight access point-to-Cisco Wireless LAN Controller Layer 3 communications.
About Radio Resource Management (RRM)Radio Resource Management (RRM)
Cisco is the only company to offer the powerful, comprehensive, and dynamic Radio Resource Manage-
ment (RRM) solution to the 802.11 market. The Radio Resource Management (RRM) (also known as
Radio Resource Management, or RRM) allows Cisco Wireless LAN Controllers to continually monitor
their associated Cisco 1000 Series lightweight access points for the following information:
• Traffic Load -- How much total bandwidth is used for transmitting and receiving traffic. This
allows WLAN managers to track and plan network growth ahead of client demand.
• Interference -- How much traffic is coming from other 802.11 sources.
• Noise -- How much non-802.11 noise is interfering with the currently assigned channel.
• Coverage -- Received Signal Strength (RSSI) and Signal to Noise Ratio (SNR) for all clients.
• Nearby APs.
Using the collected information, the Radio Resource Management (RRM) can periodically reconfigure
the 802.11 RF network within operator-defined limits for best efficiency. To do this, Radio Resource
Management (RRM):
• Dynamically reassigns channels to increase capacity and performance, both within the same
Cisco Wireless LAN Controller and across multiple Cisco Wireless LAN Controllers.
• Adjusts the transmit power to balance coverage and capacity, both within the same Cisco
Wireless LAN Controller and across multiple Cisco Wireless LAN Controllers.
• Allows the operator to assign nearby Cisco 1000 Series lightweight access points into groups to
streamline Radio Resource Management (RRM) algorithm processing.