Re: [RFC PATCH v2 0/3] l3mdev icmp error route lookup fixes

[Michael Jeanson]

On 2020-09-23 12 h 04, Michael Jeanson wrote:
> > It should work without asymmetric routing; adding the return route to
> > the second vrf as I mentioned above fixes the FRAG_NEEDED problem. It
> > should work for TTL as well.
> >
> > Adding a second pass on the tests with the return through r2 is fine,
> > but add a first pass for the more typical case.
>
> Hi,
>
> Before writing new tests I just want to make sure we are trying to fix 
> the same issue. If I add a return route to the red VRF then we don't
> need this patchset because whether the ICMP error are routed using the
> table from the source or destination interface they will reach the 
> source host.
>
> The issue for which this patchset was sent only happens when the 
> destination interface's VRF doesn't have a route back to the source 
> host. I guess we might question if this is actually a bug or not.
>
> So the question really is, when a packet is forwarded between VRFs 
> through route leaking and an icmp error is generated, which table should 
> be used for the route lookup? And does it depend on the type of icmp 
> error? (e.g. TTL=1 happens before forwarding, but fragmentation needed 
> happens after when on the destination interface)

As a side note, I don't mind reworking the tests as you requested even 
if the patchset as a whole ends up not being needed and if you think 
they are still useful. I just wanted to make sure we understood each other.

Cheers,

Michael