Extreme Networks Altitude 4700 Series, Руководство по продукции

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Altitude 4700 Series Access Point Product Reference Guide
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The AP’s hardware design uses a complex programmable logic device (CPLD). When an AP is powered on
(or performing a cold reset), the CPLD determines the maximum power available to the AP by a POE
device. Once an operational power configuration is defined, the AP firmware can read the power
setting and configure operating characteristics based on the AP’s SKU and power configuration. If the
POE cannot provide sufficient power (with all interfaces enabled), the following interfaces could be
disabled or modified:
●
Radio transmit power could be reduced due to lack of sufficient power or the radio can be disabled
●
The WAN port configuration could be changed (enabled or disabled)
For information on configuring the Access Point’s power configuration, see “Configuring Power
Settings” on page 81 .
AMSDU Transmission Support
Aggregate MAC Service Data Unit (AMSDU) is an 802.11n specific MAC feature which enhances the
transmission of multiple MSDU contents wrapped within a single preamble/packet infrastructure. The
AMSDU transmission limit is set to 3839 bites by default.
For information on configuring AMSDU support for an Access Point radio, see “Configuring the
802.11a/n or 802.11b/g/n Radio” on page 174 . AMSDU support can be defined by selecting the Set
Aggregation button within the Network Configuration > Wireless > Radio Configuration > Radio1 screen.
IPSec VPN Support
A VPN ensures data privacy between two end points, even while using a communication medium
which is itself insecure (like the Internet). VPNs create a secure tunnel between two end points as if they
are directly connected over a secure connection. Traffic is secured using a robust IPSec encryption
technique.
You can get the safety of a VPN in a WLAN by hosting the VPN server at the Access Point, and the
VPN client software on the MU. For that reason, a VPN provides secure WLAN access to MUs. A VPN
solution was more common before 802.11i was introduced, but is not as common now, since 802.11i/
WPA2 is considered more secure.
For information on configuring VPN support, see “Configuring VPN Tunnels” on page 225 . For
instructions on configuring a IPSec VPN tunnel using two Access Points, see “Creating a VPN Tunnel
between Two Access Points” on page 229 .
Theory of Operations
To understand Access Point management and performance alternatives, users need familiarity with
functionality and configuration options. The Access Point includes features for different interface
connections and network management.
The Access Point uses electromagnetic waves to transmit and receive electric signals without wires.
Users communicate with the network by establishing radio links between
mobile units (MUs) and Access
Points.
The Access Point uses DSSS (direct sequence spread spectrum) to transmit digital data from one device to
another. A radio signal begins with a carrier signal that provides the base or center frequency. The