Preamble Type; Figure 29 Wep Authentication Steps - ZyXEL Communications P-330W - V1.90 User Manual

Chapter 6 Wireless

Figure 29 WEP Authentication Steps

Open system authentication involves an unencrypted two-message procedure. A wireless
station sends an open system authentication request to the AP, which will then automatically
accept and connect the wireless station to the network. In effect, open system is not
authentication at all as any station can gain access to the network.
Shared key authentication involves a four-message procedure. A wireless station sends a
shared key authentication request to the AP, which will then reply with a challenge text
message. The wireless station must then use the AP's default WEP key to encrypt the
challenge text and return it to the AP, which attempts to decrypt the message using the AP's
default WEP key. If the decrypted message matches the challenge text, the wireless station is
authenticated.
When your P-330W's authentication method is set to open system, it will only accept open
system authentication requests. The same is true for shared key authentication. However, when
it is set to auto authentication, the P-330W will accept either type of authentication request and
the P-330W will fall back to use open authentication if the shared key does not match.

6.4.2 Preamble Type

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 clients support it.
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P-330W User's Guide