Hi Chris,
you can set filters with snoop:
test(M)-> snoop filter ?
cisco-hdlc snoop cisco hdlc protocol packet
delete delete snoop filter
ethernet snoop specified ethernet
frame-relay snoop frame relay protocol and multilink fragment packet
id snoop filter id
ip snoop ip packet
off turn off snoop filter
on turn on snoop filter
ppp snoop ppp protocol and multilink fragment packet
tcp snoop tcp packet
udp snoop udp packet
in your case you can select "ethernet".
Hope it helps,
Nadia