D-Link AirPlus DWL-900AP User manual

D-Link Air DWL-900AP
Wireless Access Point
Manual
Please see the Quick Install Guide, included separately, for installation instructions.
Building Networks for People

2
Contents
Contents of Package................................................................................3
Introduction .......................................................................................................4
LED Display......................................................................................................5
Connections .....................................................................................................6
Wireless Basics.............................................................................................7
Network Topology.....................................................................................12
Operation Modes with the DWL-900AP................................14
Network Functions of the Access Point ................................16
USB Configuration Utility....................................................................19
SNMP Management Utility................................................................27
Networking Basics....................................................................................40
Technical Specifications .....................................................................54
D-Link locations ..........................................................................................57
Limited Warranty........................................................................................58
Registration.....................................................................................................61

Contents of Package
• DWL-900AP Wireless Access Point
• Installation CD
• Quick Install Guide
• AC Adapter
• USB cable
• Power Supply/Cord
• User’s Manual
If any of the above items are missing, please contact your reseller.
System requirements:
Computer with USB port
Microsoft Windows XP, 2000, ME, 98, 98SE

4
Introduction
The D-Link Air DWL-900AP 802.11b Wireless Access Point is an ideal way
to extend the reach and number of computers connected to your wireless
network or as part of a wired LAN (Local Area Network) with a wireless
segment.
A Wireless Access Point may be used to serve different functions, including:
• Bridge - The Wireless Access Point can be used to provide
access to the shared network facilities of an Ethernet LAN.
• Wireless LAN Extension - The effective communication range of
wireless workstations can be increased.
• Improve Signal Quality - Providing a central relay station can
provide a communication path for WLAN components that
otherwise might be prevented from “seeing” other WLAN
members.
• Wireless LAN Security - The Wireless Access Point can be
configured to use encryption for improved security on a WLAN.
After completing the steps outlined in the Quick Install Guide (included
separately) you will have the ability to share information and resources, such
as files and printers, and take full advantage of a “connected” environment
for work and play!
This manual provides a quick introduction to wireless technology and its
application as it relates to networking. Take a moment to read through this
manual and familiarize yourself with wireless technology. But you should
also give yourself some time to become familiar with your new wireless
network.

LED Display
Front Panel
LED Display
On Blink Off
Power Unit is plugged in and
working normally.
Unit is booting up and
running self diagnostic
test
Unit is not plugged in
and it is off
LAN
Ethernet cable is
plugged in and there
is a valid network
connection.
The Ethernet port is
active
Ethernet cable not
plugged in or the
connection is not valid
WLAN N/A Detecting Wireless
LAN network activities
No Wireless LAN
network available in
the vicinity

6
Connections
Rear Panel
Connections
Power
5V=1A
Plug in the AC/DC adapter here. Please make sure to plug in adapter to the Wireless
Access Point before plugging the other end of the power adapter to an electrical
wall outlet or power strip.
Console
The USB console port is used to make the USB connection from the device to a
computer with the USB cable for first time configuration and configuration using the
Wireless AP USB Utility.
Ethernet The Ethernet port is used to connect the Wireless Access Point to the Ethernet LAN or a
single computer using an Ethernet cable (RJ-45).
Note: To use the USB port on the Wireless Access Point, the computer that performs
the configuration must have a USB interface with Windows XP, 2000, 98, or ME
installed. USB is not supported under Windows NT or Windows 95.
Caution: Use only the power adapter included with the
device!

Wireless Basics
D-Link Air wireless products are based on industry standards to provide easy
to use and compatible high-speed wireless connectivity within your home or
business. Strictly adhering to IEEE 802.11b, the D-Link Air wireless family of
products will allow you to access the data you want, when and where you
want it. No longer will you be tethered to a workstation or forced to run new
wiring. You will be able to enjoy the freedom that wireless networking
delivers.
A wireless LAN (WLAN) is a cellular computer network that facilitates
communication with radio signals instead of wires. Wireless LANs are used
increasingly in both home and corporate environments. Innovative ways to
utilize WLAN technology are helping people to work and communicate more
efficiently. Increased mobility and the absence of cabling and other fixed
infrastructure has proven to be beneficial for many users.
WLAN users can use the same network applications they use on an Ethernet
LAN. WLAN adapter cards used on laptop and desktop systems, support the
same protocols as Ethernet adapter cards. For most users, there is no
noticeable functional difference between a wired Ethernet desktop computer
or mobile WLAN workstation other than the added benefit of the ability to
roam within the WLAN-cell. Under many circumstances, it may be desirable
for mobile network devices to link to a conventional Ethernet LAN in order
use servers, printers or an Internet connection supplied through the wired
LAN. The Wireless Access Point is a device used to provide this link.
People use wireless LAN technology for many different purposes.

8
Wireless Basics (continued)
Mobility - Productivity increases when people have access to data in any
location within the operating range of the WLAN. Ad-hoc management
decisions based on real-time information can significantly improve worker
efficiency.
Low Implementation Costs - WLANs are easy to set up, manage, change
and relocate. Networks that frequently change, both physically and logically,
can benefit from WLANs ease of implementation. WLANs can operate in
locations where installation of wiring may be impractical. Furthermore, IEEE
standardization mandates interoperability of all WLAN devices that conform
to the 802.11b set of standards.
Installation Speed and Simplicity - Installing a wireless LAN system can be
fast and easy and can eliminate the need to pull cable through walls and
ceilings.
Installation Flexibility - Wireless technology allows the network to go where
wires cannot go.
Reduced Cost-of-Ownership - While the initial investment required for
wireless LAN hardware might be higher than the cost of wired LAN hardware,
overall installation expenses and life-cycle costs will be significantly lower.
Long-term cost benefits are greatest in dynamic environments requiring
frequent moves, adds, and changes.
Scalability - Wireless LAN systems can be configured in a variety of
topologies to meet the needs of specific applications and installations.
Configurations are easily changed and range from peer-to-peer networks
suitable for a small number of users to full infrastructure networks of
thousands of users that allows roaming over a broad area.

Wireless Basics (continued)
Our full range of D-Link Air Wireless LAN products include:
 Wireless PC cards used with laptop computers
 Wireless PCI cards used with desktop computers
 Wireless Access Points
 Wireless Home Gateways
Standards - Based Technology
The IEEE 802.11b standard designates that devices operate at an optimal
data rate of 11 Megabits per second. This means you will be able to transfer
large files quickly or even watch a movie in MPEG format over your network
without noticeable delays. This technology works by using multiple
frequencies in the 2.4GHz range utilizing Direct Sequence Spread Spectrum
(DSSS) technology. D-Link Air products will automatically sense the best
possible connection speed to ensure the greatest speed and range possible
with the technology.
Features and Standards
Wireless LAN technology is based on the internationally recognized IEEE
802.11 set of standards for wireless LANs. The Wireless Access Point is fully
compliant with the IEEE 802.11b standard and can inter-operate with other
compliant equipment.
The DWL-900AP Wireless Access Point also complies with the following
regulatory standards:
• FCC part 15 Class A with no external shielding
• FCC part 15 Class B, ETS 300-339 compliance, including CE mark
• The regulatory requirements for Japan, Europe and many other areas
of the world

10
Wireless Basics (continued)
The Wireless Access Point features include:
• Data transfer rates of up to 11 Mbps in optimal conditions
• An effective range of up to 900 feet (300 meters) outdoors or 300 feet
(100 meters) indoors
• 10BaseT Ethernet port interface for bridging Wireless LAN to an
Ethernet LAN
• Seamless roaming for notebook computers, wireless PCs, and other
computers equipped with Wireless LAN
• Built-in diagnostics including a power-up self-check
• Dual antenna assembly with optional diversity
• Firmware can be upgraded easily in the field
• Data encryption (WEP 64 and WEP 128)
• SNMP support
• DHCP support (client)
• Optional Short RF preamble
• USB Configuration
Installation Considerations
Designed to go up to 300 feet (100 meters) indoors and up to 900 feet (300
meters) outdoors, D-Link Air DWL-900AP lets you access your network from
virtually anywhere you want. Keep in mind, however, that the number and
thickness of walls, ceilings or other objects that the wireless signals must
pass thru may limit range. Typical ranges vary depending on the types of
materials and background RF noise in your home or business. The key to
maximizing range is to follow these basic principles:
1. Keep the number of walls and ceilings between the access point and
your receiving device to a minimum - Each wall or ceiling can reduce
your D-Link Air Wireless product’s range from 3-90 feet. For some

Wireless Basics (continued)
business of large residential home deployment, it may be more
beneficial to have more than one access point with overlapping
coverage.
2. Be aware of the direct line between Access Points, Residential
Gateways, and Computers - A wall that is 1.5 feet thick, at a 45
degree angle appears to be almost 3 feet thick. At a 2 degree angle it
looks over 42 feet thick! Try to make sure that the AP and Adapters
are positioned so that the signal will travel straight through a wall or
ceiling for better reception.
3. Building Materials make a difference - A solid metal door or aluminum
studs may have a negative effect on range. Again, try to position
Access Points, Residential Gateways, and Computers so that the
signal passes through drywall or open doorways and not other
materials.
4. Make sure that the antenna is positioned for best reception.
5. Keep your product away (at least 3-6 feet) from electrical devices that
generate RF noise, like microwaves, Monitors, electric motors, etc.
For the average residence, range should not be a problem. If you
experience low or no signal strength in areas of your home that you wish to
access, consider positioning the Access Point in a location directly between
the Residential Gateways and/or Computers that will be connected.
Additional Access Points can be connected to provide better coverage in
rooms where the signal does not appear as strong as desired.
Using radio frequency (RF) technology, WLANs transmit and receive data
over the air, minimizing the need for wired connections. Thus, WLANs
combine data connectivity with user mobility, and, through simplified
configuration, enable movable LANs.

12
Network Topology
The IEEE 802.11b standard supports three basic topologies for WLANs—the
Independent Basic Service Set (IBSS), the Basic Service Set (BSS), and the
Extended Service Set (ESS). Wireless LAN components can be used to
extend, enhance or entirely replace existing Ethernet infrastructure. The
DWL-900AP can accommodate any WLAN topology.
BSS
In a Basic Service Set, a wireless access point performs multiple tasks; it is
a base station and network access controller for the wireless stations in the
BSS. The access point can also provide a connection to a wired Ethernet
LAN for the BSS member stations. An example of a BSS might be a
business meeting conducted in a room with only a single Ethernet port
available. Each participant has a wireless laptop computer and requires
simultaneous access to a data server on the Ethernet LAN. A wireless
access point provides the connection to the Ethernet and acts as the network
control station for the BSS members.
In a BSS, the wireless access point performs functions similar to an Ethernet
switch. The access point controls network access and maintains a
dynamically updated list of all the members of the BSS. Members of each
BSS are added or deleted from the list as they join or leave the BSS.
Wireless stations in the BSS are identified by their MAC (Media Access
Control) address.
IBSS
An Independent Basic Service Set or ad-hoc network consists of two or
more wireless stations that communicate directly, peer-to-peer, without the
services of a wireless access point. An example of an ad-hoc network or

Network Topology (continued)I
BSS would be a group of wireless-equipped laptop computers at a trade
show set up to share information. In this arrangement, one of the WLAN units
is elected to act as a controller or base station, similar to the function of a
wireless access point except there is no connection to a wired Ethernet LAN.
Ad-hoc networks are very easy to set up and require minimal involvement by
network administrators or MIS personnel.
ESS
An Extended Service Set is a series of two or more basic service sets
networked on an Ethernet or other type of LAN. Each access point provides
connection to the Ethernet LAN for their respective BSS.
Each BSS is identified by a unique number, the BSS-ID (the MAC address of
the Wireless Access Point). Wireless stations on an ESS automatically select
the access point or BSS that can best serve them. If no access point can be
found the device will scan for a usable access point.
An ESS can be set up so that wireless stations can roam anywhere within
the range of any available access point, that is, to any member BSS, and still
maintain links to both the WLAN and the Ethernet. In this case, each station
shares a common ESS. The ESS is identified by an ESS ID number used by
all stations in the ESS.
Wireless access points can also be used to segment a wireless network.
Under such circumstances, more than one ESS might be used. Two or more
separate Extended Service Sets can occupy the same physical space. Each
station on a wireless LAN can only use one ESS.

14
Operation Modes with the DWL-900AP
Flexibility is fundamental to a wireless network. For this reason, the wireless
access point can be configured to perform different functions and customized
according to the needs of your network.
Access Point
In this mode, the access point provides access for wireless stations to wired
LANs and from wired LANs to wireless stations. Wireless stations within the
range of the access point may communicate with each other via the access
point. This is the default operation mode of the device.
Simple Wireless Access Point
Wireless Bridging
Wireless Bridge mode allows two types of connections:
1. WB Point-to-Point: The wireless bridge is configured to
communicate with a specific remote MAC address.
Wireless Bridge Point-to-Point mode

Operation Modes with the DWL-900AP (continued)
2. Wireless Bridge Point to Multipoint: The wireless bridge is
configured to communicate with any wireless bridge available on the
same channel and using the same ESS ID.
Wireless Bridge Point-to-Multipoint mode
Access Point Client Mode
The access point can also act as a client on a wireless LAN. When
configured as a client the access point functions in the capacity of a wireless
end station only. Communication through the wireless interface of the device
can only be accomplished using another Access Point functioning in AP
mode. When configured as a client, the access point connects to a single
computer or an Ethernet LAN via the Ethernet interface. An access point
configured to be a wireless client connected to a single computer is
illustrated in the figure below.
Wireless Access Point used as a Client
DWL-900AP

16
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.

Network Functions of the Access Point
(continued)
DHCP Support
The access point supports the Dynamic Host Configuration Protocol (DHCP)
used to obtain a leased IP address and network configuration information
from a remote server. When DHCP is enabled, the access point sends out a
DHCP request to obtain the IP settings and network configuration
information. The access point can be configured to download two additional
files when a boot takes place, the firmware file and an HTML file. DHCP or
BOOTP servers can be programmed to transfer these two files when a
DHCP request is made.
Media Types
The wireless access point can be used to bridge the wired Ethernet LAN and
wireless LAN radio network. The 10BASE-T Ethernet interface fully complies
with Ethernet Rev. 2 and IEEE 802.3 specifications and operates in full
duplex. The radio interface conforms to IEEE 802.11b specifications for
wireless LAN. The WLAN interface operates at speeds of up to 11 Mbps
using direct sequence radio technology. The wireless access point supports
multiple-cell operations with fast roaming between cells. With the direct
sequence system, each cell operates independently. Adding cells to the
network can increase the coverage area and total system capacity. The
access point supports wireless devices operating in Continuously Aware or
Power Save modes.
Media Access Control
All WLAN devices, like all Ethernet devices, have a unique, hardware-
encoded Media Access Control (MAC) address. Wireless LAN algorithms
employ carrier sense and collision avoidance techniques (CSMA/CA) to
ensure network access to all devices and error checking (CRC) for accuracy
of data transmissions. The method of access control used in WLAN is called
the Distributed Coordination Function (DCF).

18
Network Functions of the Access Point
(continued)
Data Transfer Rates
The actual rate at which data transmission occurs varies according to the
strength of the signal transmitting the data. Distance and environment can
effect the strength of the signal that can be transmitted and received. The
signal strength determines the type of modulation technique used to encode
data, which effects the volume of data (i.e. the number of bits) that can be
encoded in a given space of the carrier signal. The IEEE 802.11b standard
specifies that WLAN devices adapt the rate of transmission to use the best
rate achievable. Each wireless device first determines if conditions diminish
signal strength and then chooses one of four possible bit rates (1, 2, 5.5, or
11 Mbps) based on this learned information.

USB Configuration Utility
When the Wireless AP USB Configuration Utility and Wireless AP SNMP
(Simple Network Management Protocol) Utility have been installed you can
configure settings for the access point. Before you can use the SNMP Utility,
you must configure the device IP address. The IP address of the device must
be on the same subnet and use the same subnet mask as the computer
using the SNMP Utility.
Using the USB Configuration Utility
To use the USB Configuration Utility and change the IP settings of the
Access Point, follow these steps:
1. To launch the USB Configuration Utility, go to your Start menu, open
Programs, find the Wireless AP folder and open it. You will see two new
icons have been placed in this folder. Scroll to the Wireless AP USB
Utility and click on it to launch the program.
2. The Admin Password screen will ask you for a password. The default
password is “public” (all lower case), type this in the space and click OK.
3. The USB Configuration Utility management interface will appear
displaying system information about the Wireless Access Point. To
access any of the menus listed just click on the tab. If you intend to use
the SNMP Utility to manage and configure the device you must first
change the IP settings.
4. Click the IP Config tab to change the IP settings of the device.

20
USB Configuration Utility (continued)
Note: Once you have assigned or obtained an IP Address for the DWL-
900AP, through the USB Configuration Utility, we recommend that you
manage your network using the SNMP Utility (please refer to the chapter
in this manual entitled “SNMP Management Utility”.) If you choose to
manage your network using the USB Utility, you will need to connect the
DWL-900AP to a computer on your network, using the USB cable, each
time you have a management session on your network.
5. Change the IP settings of the access point. You may elect to use a
DHCP server to determine the IP settings, or set them according to
the requirements of your IP addressing scheme.
To configure the device as a DHCP client, select Enable from the DHCP
Client: pull-down menu.
To manually assign the IP settings, you must Disable the DHCP client
function and set the IP address and subnet mask. If necessary, you can
assign a Gateway IP address for the device here as well.