Hi all,
I recently encountered a phenomenon while doing traceroute and I hope everyone can provide some insights. The details are as follows:
When using ICMPv6 echo request packets for traceroute (specifically a variant called Yarrp6 (GitHub - cmand/yarrp: High-speed Internet Topology Prober) that embeds probe information like target IPv6 addresses and TTL in the payload), we captured response packets where the target address in the destination address field of the referenced ICMPv6 header was changed to a Unique Local Address starting with FD. Additionally, we noted that some of the source addresses in the IPv6 headers were these FD addresses, while others were global unicast addresses. What could explain this phenomenon?
I really appreciate any help you can provide!
Lin