def METHOD_NAME (self, pkt):
    # use scapy to parse
    scapy_pkt = Ether(pkt)
    # not ARP
    if 'ARP' not in scapy_pkt:
        return []
    # forward only ARP response
    if scapy_pkt['ARP'].op != 2:
        return []
    vlans = VLAN.extract(scapy_pkt)
    # ignore VLAN 0 - hash as empty VLAN
    vlans = vlans if vlans != [0] else []
    return self.services.get( (scapy_pkt['ARP'].pdst, scapy_pkt['ARP'].psrc, tuple(vlans)), [] ) 