## Operating Modes

A wireless client operates in either infrastructure mode or peer-to-peer mode.

### Infrastructure Mode: A wireless LAN (WLAN) with Access Points

In infrastructure mode, wireless clients send and receive information through access points. When a wireless client communicates with another, it transmits to the access point. The access point receives the information and rebroadcasts it. Then the other device receives the information.

Access points are strategically located to provide optimal coverage for wireless clients. A large WLAN uses multiple access points to provide coverage over a wide area. Access points can connect to a LAN through a wired Ethernet connection. Access points send and receive information from the LAN through this wired connection.

### Peer-to-Peer Mode: A WLAN without Access Points

In peer-to-peer mode, also called Ad Hoc Mode, wireless clients exchange information with other wireless clients without using an access point. In contrast to infrastructure mode, this type of WLAN only contains wireless clients.

You can use peer-to-peer mode to connect computers in a home or small office, or to set up a temporary wireless network for a meeting.

### Identifying Devices on a WLAN

All the devices on a WLAN use a Network Name, or Service Set Identifier (SSID) to identify the WLAN. There are several kinds of SSIDs, each having a slightly different meaning. In peer-to-peer mode, an Independent Basic Service Set Identifier (IBSSID) identifies a WLAN. In infrastructure mode, an Extended Service Set Identifier (ESSID) identifies a WLAN. For simplicity, this guide uses the term Network Name (SSID) in place of ESSID and IBSSID. In either infrastructure or peer-to-peer mode, the SSID indicates the WLAN you are communicating with. All the devices on a WLAN must use the same SSID to communicate with the other wireless devices on that WLAN. When installing an access point or wireless adapter in a wireless client, the software asks you to specify an SSID.

All adapters and access points in a WLAN use a Network Name, or Service Set Identifier (SSID) to identify the WLAN. The SSID indicates what WLAN you are communicating with. In software and documentation, the terms SSID and Extended Service Set Identifier (ESSID) are used interchangeably.

The Broadcast SSID feature allows stations to associate with the access point when they send probe packets using a broadcast SSID. If enabled, anyone can associate with the access point using a null SSID. By default, this feature is disabled and the access point responds only to stations that use the correct Network Name (SSID).

A Basic Service Set Identifier (BSSID) uniquely defines each wireless device. The BSSID is the Ethernet Media Access Control (MAC) address of the wireless adapter installed in the wireless client. The MAC address is permanently set when the adapter is manufactured. MAC addresses determine the device sending or receiving data. A MAC address is a 48-bit number written as six hexadecimal bytes separated by colons. For example:

> 00:A0:F8:24:9A:C8

To find the MAC address of an Intel® PRO/Wireless LAN device, see the product label at the bottom of the device.

## Site Requirements

Because the client adapter is a radio device, it is susceptible to Radio Frequency (RF) obstructions and other sources of interference that can reduce throughput and range. Follow these guidelines to ensure the best possible performance:

- Install the client adapter in an area where large steel structures such as shelving units, bookcases, and filing cabinets will not obstruct radio signals to and from the client adapter.
- Do not install the client adapter near microwave ovens. Microwave ovens operate on the same frequency as the client adapter and can cause signal interference.

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