User's Manual

SPEEDLAN 4100 & 4200 Installation and Operation User Guide
Configuring SPEEDLAN 4100 & 4200 5-7
Setup 2 Button - 11 Mb RF Interface Setup
To modify the 11 Mb RF Interface Setup, click the Setup 2 button on the Interface Setup or
Advanced Interface Setup dialog box. This dialog box displays the configuration settings that control
the individual interfaces and how they communicate with each other. On the next page, you will find
a description of the settings, as well as how they affect the brouter's performance of the interfaces.
Transport Methods
The industry compatible method of transmitting and receiving data over wireless networks will cause
data packets to frequently be lost. This is due to the fact that a wireless network does not have the
ability to detect collisions like a wired Ethernet network. On an Ethernet network, collisions can be
detected by the hardware and are automatically retransmitted. Ethernet is referred to as CSMA/CD
(Carrier Sense Multiple Access with Collision Detection). Wireless networks are CSMA/CA (Carrier
Sense Multiple Access with Collision Avoidance). Collisions cannot be detected because wireless
cannot receive and transmit at the same time. This means brouters are not able to listen for
collisions. A brouter that is operating properly in a point-to-point network will loose, due to
collisions, less than 1% of the transmitted packets. This packet loss is not normally a problem with
protocols such as Novell IPX (without the Burst Mode NLM), but may cause networks using most