On Wed, 7 Nov 2018 12:09:51 +0100
Jiri Benc <jb...@redhat.com> wrote:
> On Tue, 6 Nov 2018 22:38:56 +0100, Stefano Brivio wrote:
> > - patch 1/11 adds a socket lookup for UDP tunnels that use, by design,
> > the same destination port on both endpoints -- i.e. VxLAN and GENEVE
>
> This is not necessarily true with lwtunnels (collect_md mode of VXLAN
> and GENEVE). While any sane setup will use the same dst ports, there's
> really nothing that enforces it. Of course, in that case we have no way
> to map the ICMP error back to the tunnel.
Right, thanks for pointing that out. I will expand on that in the
comments to __udp{4,6}_lib_err_encap().
> Generally speaking, I'm not sure how ICMP error handling should work
> for external control planes. Are we sure they want PMTU discovery and
> route redirection done by the kernel? (I am not sure, neither way.)
I'm not sure either, even though I have a slight preference on
making this work by default, rather than not even giving lwtunnels a
chance by dropping ICMP messages, as it currently stands.
By the way, if needed, it's easy to disable or make it configurable:
- in geneve_udp_encap_err_lookup():
if (gs->collect_md)
return -ENOENT;
- in vxlan_err_lookup():
if (vxlan_collect_metadata(gs))
return -ENOENT;
but I would rather deal with this at a later moment, and only if the
need arises.
--
Stefano
