Dear NANOG folks, As you know, traceroute is unable to enumerate routers on the reverse path. Given that paths through the public internet are usually asymmetric, knowing the reverse path would be beneficial e.g. for troubleshooting purposes (https://youtu.be/L0RUI5kHzEQ?t=2312). We have implemented a reverse traceroute tool (https://github.com/hsanet/reverse-traceroute), both client and server for both IPv4 and IPv6. We are also in the process of specifying the protocol at the IETF (https://datatracker.ietf.org/doc/html/draft-heiwin-intarea-reverse-tracerout...). We also gave a talk on reverse traceroute at DENOG14 (https://youtu.be/Y7NtqLEtgjU). If you would like to play with reverse traceroute, the easiest option is to work with the client and use one of the public server instances (https://github.com/HSAnet/reverse-traceroute/blob/main/ENDPOINTS). If you would be willing to host a public server instance yourself, please reach out to us. Also, if you find this work useful, please start discussing the work at the IntArea WG at the IETF. If you have any questions or comments, just drop us a line, file an issue on github and/or use the IntArea mailing list. Thanks a bunch, Rolf