On 5/28/25 1:28 AM, Robert Elz wrote:
By making that be a LL addr, we know the redirect came from on our local link, and if it is also the addr to which we sent the packet to be forwarded, then it probably is coming from that router, and is a valid instruction to send further packets to the addr given in the redirect (which will be another LL addr on the same link.)
The reason why I asked here about the defaultroute and one of the things we found debugging the earlier instance this year: we observed asymmetric behavior for nexthop and ICMP6 source. That is the NetBSD machine is sending to one next hop and the ICMP6 comes back with a different IP6 address and therefore refused. If you are absolutely sure that your router is always going to use the global address for its processing, there should be nothing magical about link-local addresses. That's not the observed behavior.
Joerg