Proxim 7550 Manual page 45

Configure the PC Card to use the Shared Key option if you have
802.11b products on your network that support the optional
Shared Key Authentication feature. However, if you select the
Shared Key option, all 802.11b devices on the network must
have the same Encryption Keys.
The Harmony 802.11b Access Point supports Shared Key
Authentication when set to either Use WEP for Authentication
or Use WEP for Authentication and Encryption. The Harmony
802.11b PC Card only supports Shared Key Authentication
when WEP is enabled. Therefore, if you want the Harmony
802.11b PC Card to use both Shared Key Authentication and
WEP, you must also configure the Harmony 802.11b Access
Point to Use WEP for Authentication and Encryption.
Refer to the Harmony 802.11b Access Point Model 8550 User's
Guide for information on the Access Point's WEP features.
Fragmentation Threshold
In harsh environments with interference and other negative radio
phenomena, an 802.11b device may have no difficulty receiving
small packets but large packets may be frequently corrupted.
In this case, you may want the transmitting 802.11b device to
break up a large packet into several smaller packets to increase
the likelihood that data will be successfully received by another
node. This process is known as "fragmentation."
You may configure a Harmony 802.11b PC Card to fragment
packets of a certain size or larger.
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