Network Functions Of The Access Point - D-Link Air DWL-900AP User Manual

Network Functions of the Access Point

The wireless access point performs key network functions controlling access
to both the wireless and Ethernet LANs. The following paragraphs elaborate
on the network function of the wireless access point.
DWL-900AP Bridging
The Wireless Access Point functions as an intelligent bridge. It listens to all
data traffic on all its interfaces and maintains a MAC address database in
much the same way that an Ethernet switch maintains a MAC address table.
MAC address information is updated dynamically and MAC addresses that
are inactive for a specified period are deleted from the database or "aged
out." The MAC address database also indicates the type of interface being
used by each entry (either WLAN or Ethernet.) Packets destined for unknown
MAC Addresses are forwarded to the Ethernet interface.
When necessary, the Wireless Access Point uses the Address Resolution
Protocol (ARP) to match IP addresses to MAC addresses and stores ARP
information in its database as well. ARP information is likewise aged out of
the database.
Filtering and Access Control
The wireless access point can limit the wireless devices that associate with it
and the data packets that are forwarded through it. Filters can provide a
degree of security and improve network performance by eliminating
broadcast/multicast packets from the radio network.
The ACL (Access Control List) contains the MAC address of every wireless
device allowed to associate with the access point. This prevents
unauthorized access to network resources.
The access point can discriminate based on the destination address of
packets it handles by maintaining a list of disallowed destinations. This can
improve efficiency by eliminating unnecessary transmission of data packets.
The type of packet forwarded through the access point can be controlled
using a filter. Type Filtering prevents specific packets from being processed.
Certain packet types such as broadcast packets from devices not important
to the wireless LAN are discarded to preserve bandwidth. Filtering out
unnecessary frames can improve overall network performance.
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