Ask about ethernet package

[Marcio Henrique Leiner <marcio@genoma4.iq.usp.br>]

Hi all,
	I was looking in some tcpdump output, and I have seen the
following package some times:

20:02:16.067095 XX:XX:XX:XX:XX:XX > XX:XX:XX:XX:XX:XX sap f0 rr (r=8,P)
len=42
                         0000 0000 0000 0000 0000 0000 0000 0000
                         0000 0000 0000 0000 0000 0000 0000 0000
                         0000 0000 0000 0000 0000

basicaly are two ethernet interface that send this package. I am wondering
myself if it is or isn't normal. For, with little administration 
experience, that looks a little extrange. Or is it some kind of control
package.