Huawei quidway s7700 Configuration Manual page 159

Quidway S7700 Smart Routing Switch
Configuration Guide - SPU
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Terms
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Issue 01 (2011-07-15)
1. The AP starts and discovers the AC in unicast, multicast, or broadcast mode. In unicast
mode, the AP discovers the AC by means of Dynamic Host Control Protocol (DHCP)
discovery, Domain Name System (DNS) discovery, or static configuration.
– DHCP discovery: The AP sends a DHCP request packet to apply for an IP address
from the AC. The AC allocates an IP address to the AP by sending a DHCP reply
packet carrying the Option 43 field that contains the AC's IP address. This allows
the AP to discover the AC.
– DNS discovery: The AP uses the DNS function to obtain the AC's IP address.
– Static configuration: The AC's IP address is configured on the AP manually.
2. After the AP obtains the AC's IP address, it negotiates with the AC by sending a request
message. After the AP receives a response message from the AC, it starts to establish
a Control And Provisioning of Wireless Access Points (CAPWAP) tunnel with the
AC. The CAPWAP tunnel uses the Datagram Transport Layer Security (DTLS)
protocol to encrypt and transmit User Datagram Protocol (UDP) packets.
3. After the CAPWAP tunnel is established, the AP sends a Join Request message to the
AC. The AC determines whether to allow the AP to join the AC and sends a Join
Response message to the AP.
4. The AP checks whether it is running the latest software version based on negotiation
parameters. If the current version is not the latest version, the AP obtains the latest
software version from the AC by using the CAPWAP tunnel. After the software
version is updated, the AP restarts, discovers the AC, establishes a CAPWAP tunnel
with the AC, and joins the AC again.
5. The AP sends a configuration status request message to the AC to notify the AC of
the local configuration, including the antenna, radio, rate, channel, and power
configurations. After receiving this message, the AC immediately sends a
configuration status response message to the AP so that the AP can update the
configuration.
6. After the configuration is updated, the AP sends a status change request message to
the AC to notify the AC of the configuration update result. The AC then responds with
a status change response message.
7. After the AP receives the status change response message, it enters the normal state
and starts to function.
A wireless link is established between a STA and an AP in the following process:
1. Multiple APs on the WLAN periodically send Beacon frames. When a STA receives
Beacon frames from multiple APs, it selects an AP as the access device.
2. The selected AP performs 802.11 authentication for the STA. After the STA is
authenticated, it sends an association request to the AP. The AP forwards the
association request to the AC. The AC determines whether to allow the STA to join
itself. If the STA is allowed to join the AC, the AC sends a STA configuration request
message to the AP.
3. The STA triggers 802.1x authentication by dialing. After the STA is authenticated by
the AP, it is associated with the AP.
STA
A STA is a computer with a wireless network adapter.
AP
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5 WLAN Configuration
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