Hi
It depends on which OS you are running the traceroute from. On Unix/Linux Systems, default packet type created is a UDP packet. The first packet will be addressed to udp/33435 and each subsequent packet will be addressed to an incremented port number. This allows traceroute to keep track of which return ICMP packets correspond to which outbound packets.
But on Windows, traceroute is implemented by sending ICMP Echo packets.
