reverse_icmp6_type(uint8_t type)
{
    switch (type) {
    case ICMP6_ECHO_REQUEST:
        return ICMP6_ECHO_REPLY;
    case ICMP6_ECHO_REPLY:
        return ICMP6_ECHO_REQUEST;
    default:
        OVS_NOT_REACHED();
    }
}
reverse_icmp6_type(uint8_t type)
{
    switch (type) {
    case ICMP6_ECHO_REQUEST:
        return ICMP6_ECHO_REPLY;
    case ICMP6_ECHO_REPLY:
        return ICMP6_ECHO_REQUEST;
    default:
        OVS_NOT_REACHED();
    }
}