As u may know, I play around with segment-routing. However, I have issues with the MTU. If I encap from the gateway to the clients and do iperf3 tests, I need to somehow adjust the MTU on the "client-(router)"-side.
I can set the MTU differently on the client directly, on the route to the gateway, or on the interface that goes to the gateway.
I thought via
ra_mtu I could advertise a max-mtu? Somehow the clients do not respect those settings? That would be the easiest solution for me.
Doesn't PMTUD work in your case?
It may require permissive firewall rules for ICMP.
Actually, I always thought it should... Debugging this, I already saw errors that were signaling "Package To Big". It seems that they do not arrive at the corresponding target. I will inspect that in more detail, but currently I was searching for a workaround.
I think i will put all that segment-routing stuff, to some wiki artikel.
BTW, if someone reads that here, I would prefer
inline ecanspulation. I had to rewrite my xdp stuff to inline, since IPQ40XX SOCs suddenly went crazy (with outer encapsulation). ^^
Okay, I have to correct me. Use encap whenever possible, but if u need to use inline, you have to de-encapsulate the packets yourself, if the endpoint is not in the segment-list itself (e.g. you want to send it to your clients). You can do this with XDP, like I did here.