I recently resolved an issue in which a non-Cisco client would not fully associate with Cisco AP's that had the "Ethernet Encapsulation Transform" setting on their radio interfaces set to 802.1H. Changing the setting to RFC1042 resolved the problem.
1) What is the default setting (and has this ever changed)? I find conflicting statements in the documentation.
2) Since the 802.1H setting is apparently optimized for performance of Cisco products (and RFC1042 is optimized for interoperability of non-Cisco equipment), how much is the performance going to be degraded with the Cisco clients by using the RFC1042 setting?
802.1H is Cisco Proprietary and that it is a bit more effecient than RFC1042
Data packets that are not 802.2 packets must be formatted to 802.2 via 802.1H or RFC1042. Cisco Aironet equipment uses 802.1H because it provides optimum interoperability.
802.1H - This default setting provides optimum performance for Cisco Aironet wireless products.
RFC1042 - Use this setting to ensure interoperability with non-Cisco Aironet wireless equipment. RFC1042 does not provide the interoperability advantages of 802.1H but is used by other manufacturers of wireless equipment.