3Com AirConnect User Manual - page 24

24

C

HAPTER

 1: O

VERVIEW

OF

 D

IGITAL

 W

IRELESS

 N

ETWORKING

them to the wireless client and the wireless client goes back to sleep. A DTIM field, 

also called a countdown field, informs wireless clients of the next window for 

listening to broadcast and multicast messages. The AP sends the messages 

following the 

nth beacon

 where 

n 

is the DTIM interval defined in the AP. When the 

AP has buffered broadcast or multicast messages for associated wireless clients, it 

sends the next DTIM with a DTIM Interval value. This value decreases by '1' with 

each successive beacon. The AP sends broadcast and multicast messages 

immediately following the beacon where the DTIM value is '0.' To prevent a 

PSP-mode wireless client from sleeping through a DTIM notification, select a PSP 

mode value less than or equal to the DTIM value. PSP-mode wireless clients hear 

the beacons and awaken to receive the broadcast and multicast messages.

A TIM is a compressed virtual bitmap identifying the AP associated wireless clients 

in PSP mode that have buffered directed messages. wireless clients issue a poll 

request when APs issue a TIM. A beacon with the broadcast-indicator bit set 

causes the wireless client to note DTIM Count field value. The value informs the 

wireless client of the beacons remaining before next DTIM. This ensures the 

wireless client turns on the receiver for the DTIM and the following BC/MC packet 

transmissions.

HTTP, HTML Web Server

Support

Hypertext Transfer Protocol (HTTP) is the native language of the World Wide Web. 

The HTTP protocol makes requests from browsers to servers and responses from 

servers to browsers. This function provides the user with a Web-based format for 

configuration and firmware download. 

Web pages are written in Hypertext Markup Language (HTML). HTML allows the 

user to create Web pages containing text, graphics, and pointers or links to other 

Web pages or elsewhere on the page or document. Pointers are known as 

Uniform Resource Locators (URLs). A URL is essentially the name of the Web page. 

The URL consists of three parts:

1 Protocol (or Scheme)

2 Fully Qualified Domain Name (FQDN), the machine where the page is located

3 Local name that identifies the page (usually the HTML file name).

The HTML language describes how to format the document, indication which 

fonts to use, much like a copy editor describes which fonts to use, such as the 

location, color, header size and text. 

Management Options

Managing AirConnect includes viewing network statistics and setting 

configuration options. Statistics track the network activity of associated wireless 

clients and data transfers on the AP interfaces. Configuration involves, among 

other things, setting system operating parameters and filters used in bridging.

The AP requires one of the following to perform a custom installation or maintain 

the AirConnect network:

■

Simple Network Management Protocol (SNMP).

■

Wired or wireless LAN workstation with a telnet client.

■

Terminal or PC with RS-232 connection and access to ANSI emulation.