[ovs-discuss] OVN using the wrong SNAT for established connections

[Brendan Doyle]

Hi,


So I have a Distributed router port gateway that had the following NAT entry

     nat 2dbfe551-50ff-43f3-b8b0-7d2e857dea8c
         external ip: "253.255.80.24"
         logical ip: "10.117.0.0/23"
         type: "snat"

A VM with IP 10.117.0.3 is using this to mount a filesystem in the 
underlay, all works fine
it's 10.117.0.3 is SNAT'd to 253.255.80.24.

Another NAT entry is added, so we have:

     nat 2dbfe551-50ff-43f3-b8b0-7d2e857dea8c
         external ip: "253.255.80.24"
         logical ip: "10.117.0.0/23"
         type: "snat"
    nat 80572056-3bfd-4b10-abd0-4c084cd73474
         external ip: "253.255.80.30"
         logical ip: "10.117.0.0/24"
         type: "snat"


I expect OVN to now SNAT 10.117.0.3 to 253.255.80.30 based on the 
longest prefix match.
But it does not, it SNAT' to 253.255.80.24. If I umount the filesystems 
originally mounted when
there was only the /23 SNAT entry. i.e the TCP connections are closed. 
Then I see OVN SNAT'ing
to the correct IP with the longest prefix.

It seems that the longest prefix match is not applied if there 
established TCP connections?

What's the expected behavior here?

Brendan.