ZyXEL NBG-416N Guia Do Utilizador

 Appendix D Wireless LANs

NBG-416N User’s Guide

A Fragmentation Threshold is the maximum data fragment size (between 256 
and 2432 bytes) that can be sent in the wireless network before the AP will 
fragment the packet into smaller data frames.

A large Fragmentation Threshold is recommended for networks not prone to 
interference while you should set a smaller threshold for busy networks or 
networks that are prone to interference.

If the Fragmentation Threshold value is smaller than the RTS/CTS value (see 
previously) you set then the RTS (Request To Send)/CTS (Clear to Send) 
handshake will never occur as data frames will be fragmented before they reach 
RTS/CTS size.

A preamble is used to synchronize the transmission timing in your wireless 
network. There are two preamble modes: Long and Short. 

Short preamble takes less time to process and minimizes overhead, so it should 
be used in a good wireless network environment when all wireless stations 
support it. 

Select Long if you have a ‘noisy’ network or are unsure of what preamble mode 
your wireless stations support as all IEEE 802.11b compliant wireless adapters 
must support long preamble. However, not all wireless adapters support short 
preamble. Use long preamble if you are unsure what preamble mode the wireless 
adapters support, to ensure interpretability between the AP and the wireless 
stations and to provide more reliable communication in ‘noisy’ networks. 

Select Dynamic to have the AP automatically use short preamble when all 
wireless stations support it, otherwise the AP uses long preamble.

Note: The AP and the wireless stations MUST use the same preamble mode in order 

to communicate.

IEEE 802.11g is fully compatible with the IEEE 802.11b standard. This means an 
IEEE 802.11b adapter can interface directly with an IEEE 802.11g access point 
(and vice versa) at 11 Mbps or lower depending on range. IEEE 802.11g has