def _description(pkt):
    """Return description of packet."""
    eth_type = pkt('eth_type')
    if eth_type == 2054:
        arp_op = pkt('arp_op')
        if arp_op == 1:
            return 'ARP:REQ'
        if arp_op == 2:
            return 'ARP:REPLY'
        return 'ARP:%s' % arp_op
    if eth_type == 2048:
        ip_proto = pkt('ip_proto')
        if ip_proto == 1:
            return 'ICMPv4'
        if ip_proto == 2:
            return 'IGMPv4'
        if ip_proto == 6:
            return 'TCPv4'
        if ip_proto == 17:
            return 'UDPv4'
        return 'IPv4:%s' % ip_proto
    if eth_type == 34525:
        ip_proto = pkt('ip_proto')
        if ip_proto == 58:
            return 'ICMPv6'
        if ip_proto == 6:
            return 'TCPv6'
        if ip_proto == 17:
            return 'UDPv6'
        return 'IPv6:%s' % ip_proto
    if eth_type == 35020:
        return 'LLDP'
    return 'ETH:%s' % eth_type
