I have found this in my wireless network card's properties in connection. What is this? Should i enable it?
Cisco Compatible eXtensions (CCX) are a set of Cisco-proprietary additions to the 802.11 family of wireless LAN (WLAN) protocols. In general, if you're connecting to a WLAN that uses Cisco enterprise-class gear, you should enable them. If not, it probably doesn't matter much.
In the 802.11 WLAN market, Cisco usually rolls out new Cisco-proprietary features as soon as they see a market need, and then they later take those new proprietary advances to the IEEE and get them standardized as some future part of the 802.11 family of WLAN protocols.
But since Cisco doesn't make WLAN client cards any more, they have to rely on third-party 802.11 client card vendors to implement these Cisco-specific features on their client cards. To encourage that, Cisco works with 802.11 chipset vendors to get them to support these features, so that the end products support these features. Anyone creating 802.11 client cards can sign up to be part of the CCX program, enable these Cisco-specific features, and pay to have Cisco certify them as CCX-compliant, which might boost their sales to large institutions that have Cisco-based WLANs and want to use these features.
At first, Cisco saw a need for enterprise-class security features for WLANs, before the IEEE was finished creating 802.1X (Extensible Authentication Protocol (EAP) over LANs) for wired LANs, much less 802.11i for 802.1X authentication (and other major security improvements) on WLANs. So Cisco took an early snapshot of 802.1X, selected a single authentication method for it, and found their own way to integrate it with 802.11. The result was Cisco's "LEAP" (Lightweight EAP). So one of the earliest versions of CCX certification was basically showing that your client supported LEAP. Cisco wasn't alone in recognizing that enterprise-class security was needed for WLANs; the Wi-Fi Alliance (known as the Wireless Ethernet Compatibility Alliance or "WECA" at the time) created Wi-Fi Protected Access (WPA) before the IEEE finished creating 802.11i. Later 802.1X and 802.11i were ratified and Cisco deprecated LEAP, but by then Cisco had moved on to other things to focus CCX on.
Overall, CCX includes enhancements in several areas, including, but not limited to:
But again, because these enhancements are often Cisco-proprietary, they only work when your client is connected to a Cisco-based WLAN, so they don't make much difference if you're connecting to a non-Cisco WLAN. Also, note that when I say "Cisco-based", I mean real Cisco enterprise-class gear, not "Cisco-Linksys" consumer-grade gear.