Sacado del "man traceroute" de Linux:
default
The traditional, ancient method of tracerouting. Used by default.
Probe packets are udp datagrams with so-called "unlikely" destination ports. The "unlikely" port of the first probe is 33434, then for each next probe
it is incremented by one. Since the ports are expected to be unused, the destination host normally returns "icmp unreach port" as a final response.
(Nobody knows what happens when some application listens for such ports, though).
This method is allowed for unprivileged users.
icmp -I
Most usual method for now, which uses icmp echo packets for probes.
If you can ping(8) the destination host, icmp tracerouting is applicable as well.