o'reilly ccna books

o'reilly ccna books.frame, and typically adds an 802.1qVLAN tag, and then forwards the frame to the appropriate wired network. Step 5 The packet is then transmitted over the wired switching and routing network architecture to Host B. Upon receipt of the frame, Host B may respond. When Host B returns an IP packet to Host A. The steps are as follows. Step 1 The packet begins transmission from Host B and arrives at the WLC via the wireline switching and routing network, where the Ethernet frame uses the MAC address of Host A as the destination MAC.Here the Ethernet frame uses the MAC address of host A as the destination MAC address. The IP packet from host B is encapsulated in the Ethernet frame.Step 2 The WLC takes the entire Ethernet frame, adds the LWAPP header with the C bit set to 0, and then encapsulates the combined frame in an LWAPP Ethernet frame. The LWAPP Ethernet frame uses the WLCMAC address as the source MAC address and the AP Ethernet MAC address as the destination MAC address. The frame is sent to the AP via the switched network.Step 3 On the AP, remove and process the Ethernet and LWAPP headers.148 Chapter 11 Discovering and Associating ControllersStep 4 The payload (IP packets) is then encapsulated into an 802.11MAC frame and transmitted over the air by the AP to Host A.2. the LWAPP Layer 3 transport modelAs mentioned above, Cisco prefers the Layer 3 LWAPP mode. This is because Layer 3 LWAPP is more scalable than Layer 2 LWAPP. Layer 3 LWAPP control and data messages are transmitted as User Datagram Protocol (UDP,UserDatagramProtocol) packets over the IP network. All CiscoWLC platforms and lightweight APs support Layer 3 LWAPP.The only requirement is to establish an IP connection between the AP and the WLC. The source and destination addresses of the LWAPP tunnel use the IP address of the AP and the IP address of the AP-ManagerInterface of the WLC. On the AP side, both LWAPP control and data messages use a temporary port as the UDP port, which is derived from a hash of the APMAC address. On the WLC side, LWAPP data messages always use UDP port 12222, and LWAPP control messages always use UDP port 12223o The client sends frames in Layer 3 LWAPP mode similar to Layer 2 mode.3 However, the frames are then encapsulated in UDP. This process is described below.Step 1 Host A sends a packet on the 802.11RF interface. The packet is encapsulated in an 802.11 frame with the MAC address of Host A as the source address and the AP radio interface MAC address as the destination address.