From the FWSM config guide

"

An EtherType ACE controls any EtherType identified by a 16-bit hexadecimal number.

EtherType access lists support Ethernet V2 frames.

802.3-formatted frames are not handled by the access list because they use a length field as opposed to a type field.

BPDUs, which are handled by the access list, are the only exception: they are SNAP-encapsulated, and the FWSM is designed to specifically handle BPDUs. "

http://www.cisco.com/en/US/docs/security/fwsm/fwsm32/configuration/guide/traffc_f.html

Syed Iftekhar Ahmed