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.
