User's Manual

SPEEDLAN 8500 Series Installation and Operation User Guide
5-8 Configuring SPEEDLAN
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 IDUs are not able to listen for collisions. A
IDU 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 other protocols to experience
poor performance. SectorPRC helps to alleviate this problem by placing multiple packets into one
larger packet, which saves bandwidth by eliminating the extra overhead. The transport methods are
described:
This actually
controls the "Link
Integrity" lights on
the front panel of
the IDU, and it is
turned ON by
default. Wave
W
ireless highly
recommends that
you leave it
enabled.