MAC Address and VIP's

I am confused as to what I am seeing from the F5, when I do a sh arp on my FW for a VIP I see a MAC address of an interface on my F5 that isn't even connected to my network. Can anyone help me out with understanding this?

 

 

Output from my FW

 

 

 

sh arp | inc 172.20.66.24

 

172.20.66.24 0001.d7e9.b245 1543

 

 

 

 

 

 

 

 

 

 

 

 

DOWN 1.2 0:1:d7:e9:b2:45 1000 0