Date: Sun, 05 Dec 2021 20:53:33 UTC
On Sun, Dec 05, 2021 at 08:20:08PM +0200, John Hay wrote: > Something I have observed is that if you use FreeBSD 13 as a router with 2 > subnets on the same interface, it will generate redirects when hosts send > packets to the other subnet via the FreeBSD router. I think it is wrong. No, it's correct. > The host does not have a more direct way to get to the other subnet. The other host can arp for an address in a non-connected network on the interface because it's the same L2 domain. Hence the ICMP redirect is send out to provide the shortcut (skipping the router). > RFC792 > on page 13 does not talk about interfaces, but networks, "If G2 and the > host identified by the internet source address of the datagram are on the > same network...". "network" == "layer 2 domain".