Normal Original BZ/Issue:
https://bugzilla.redhat.com/show_bug.cgi?id=2238969
https://issues.redhat.com/browse/FD-3153
Description of problem:
This BZ is related to:
- https://bugzilla.redhat.com/show_bug.cgi?id=2238494: this BZ refers to E/W traffic only.
- https://bugzilla.redhat.com/show_bug.cgi?id=1833813: this BZ tested only the case when the external network MTU was smaller than the internal network MTU.
The traffic between an external network and the internal one is routed using an OVN router. The external network is defined as gateway network.
In this BZ the condition is MTU external > MTU internal. In this case, Neutron does not set the gateway LRP:options:gateway_mtu, because the external MTU is greater. However:
- When the traffic (for example a ping) with MTU bigger than internal network MTU is sent from an external device, the
Version-Release number of selected component (if applicable):
How reproducible:
Steps to Reproduce:
1. Deploy an OpenStack environment, using any OVN (geneve, vxlan) backend type: https://rhos-ci-jenkins.lab.eng.tlv2.redhat.com/view/QE/view/OSP17.1/
2. By default, any deployment using Jenkins will provide a flat external network named "public" with MTU=1500.
3. Create an internal network with smaller TMY:
$ openstack network create --mtu 1200 private
$ openstack subnet create --network private --subnet-range 10.0.120.0/28 sprivate
4. Create a router connecting both networks:
$ openstack router create router1
$ openstack router set --external-gateway public router1
$ openstack router add subnet router1 sprivate
5. Create a server and a floating ip:
$ openstack server create --network net1 --flavor cirros --image cirros server1
$ openstack floating ip create public
$ openstack floating ip set --port <VM_port> <FIP>
6. From the undercloud environment, ping the FIP with MTU=1400:
$ ping <FIP> -M want -s 1400
Actual results:
The packet is fragmented when reaching the VM TAP device.
Expected results:
No packet is received in the VM TAP device.
Additional info:
