Cisco Cisco Aironet 350 Mini-PCI Wireless LAN Client Adapter Guia Do Desenho
2-5
Enterprise Mobility 4.1 Design Guide
OL-14435-01
Chapter 2 Cisco Unified Wireless Technology and Architecture
LWAPP Overview
Layer 3 Tunnel
Layer 3 LWAPP is the recommended tunnel type. This method uses IP UDP packets to facilitate
communication between the LWAPP AP, and the WLC. L3 LWAPP is able to perform fragmentation and
reassembly of tunnel packets; thereby allowing client traffic to make use of a full 1500 byte MTU and
not have to adjust for any tunnel overhead.
communication between the LWAPP AP, and the WLC. L3 LWAPP is able to perform fragmentation and
reassembly of tunnel packets; thereby allowing client traffic to make use of a full 1500 byte MTU and
not have to adjust for any tunnel overhead.
Note
In order to optimize the fragmentation and reassembly process, the number of fragments that the WLC
or AP expect to receive is limited. The ideal supported MTU size for deploying the Cisco Unified
Wireless network is 1500, but the solution operates successfully over networks where the MTU is as
small as 500 bytes.
or AP expect to receive is limited. The ideal supported MTU size for deploying the Cisco Unified
Wireless network is 1500, but the solution operates successfully over networks where the MTU is as
small as 500 bytes.
The following are some Layer 3 LWAPP packet captures to illustrate LWAPP operation. The sample
decodes were captured using a Wireshark Network Analyzer.
decodes were captured using a Wireshark Network Analyzer.
Note
The Wireshark’s default configuration does not decode Cisco LWAPP packets correctly. This can be
corrected by using the “SWAP Frame Control” option under protocol preferences.
corrected by using the “SWAP Frame Control” option under protocol preferences.
LWAPP Control Packet shows a decode of an LWAPP control packet. This packet originates from the
WLC using UDP source port 12223 (as do all LWAPP control packets from the WLC). Control Type 12
represents a configuration command used to pass AP configuration information to the LWAPP AP by the
WLC. Control packet payloads are AES encrypted, using keys derived from the PKI authentication
process that is performed when an LWAPP AP first establishes a connection with the WLC.
WLC using UDP source port 12223 (as do all LWAPP control packets from the WLC). Control Type 12
represents a configuration command used to pass AP configuration information to the LWAPP AP by the
WLC. Control packet payloads are AES encrypted, using keys derived from the PKI authentication
process that is performed when an LWAPP AP first establishes a connection with the WLC.
Figure 2-3
LWAPP Control Packet
802.11 Probe Request in LWAPP shows a decode of an LWAPP packet containing an 802.11 probe
request. This packet originates from the LWAPP AP to the WLC using UDP port 12222, as do all
LWAPP-encapsulated 802.11 frames. In this example, RSSI and SNR values are also included in the
LWAPP packet to provide RF information to the WLC.
request. This packet originates from the LWAPP AP to the WLC using UDP port 12222, as do all
LWAPP-encapsulated 802.11 frames. In this example, RSSI and SNR values are also included in the
LWAPP packet to provide RF information to the WLC.