Remember that the definition of Wi-Fi came after completion of the IEEE 802.11 standard. However, the major Wi-Fi manufacturers decided that security was so important to end users that it had to move as fast as possible to deliver a replacement for WEP. Furthermore, they concluded that customers would not be prepared to just throw away all their existing Wi-Fi equipment in order to switch to RSN; they would want to upgrade their products through software. To address this need, Task Group i started to develop a security solution based around the capabilities of existing Wi-Fi products. This led to the definition of the Temporal Key Integrity Protocol (TKIP), as described in Chapter 11. TKIP is allowed as an optional mode under RSN.
The development of TKIP was a great help to allow upgrade of existing systems, but the industry couldn't wait until the lengthy process of standards ratification was completed. Therefore, the Wi-Fi Alliance adopted a new security approach based on the draft RSN but only specifying TKIP. This subset of RSN is called Wi-Fi Protected Access (WPA). Many leading vendors have now produced software upgrades so existing product can be converted to support WPA and most new products are now shipped with WPA capability. The Wi-Fi Alliance has created a test plan for WPA so vendors can ensure interoperability.
Cases in which the industry has run ahead of standards are not that uncommon. This has happened a number of times in modem technology and sometimes has led to two factions of the industry selling incompatible products. Fortunately, the Wi-Fi Alliance has avoided this type of a split and most manufacturers are supporting the Wi-Fi WPA specification.