Bug 2108212

Summary:	[OSP17] During OVN migration workload VMs became not reacheable via IPv6
Product:	Red Hat OpenStack	Reporter:	Roman Safronov <rsafrono>
Component:	openstack-neutron	Assignee:	Miro Tomaska <mtomaska>
Status:	ON_DEV ---	QA Contact:	Eran Kuris <ekuris>
Severity:	medium	Docs Contact:	James Smith <jamsmith>
Priority:	high
Version:	17.0 (Wallaby)	CC:	bcafarel, chrisw, ekuris, jamsmith, lsvaty, mburns, mtomaska, pgrist, scohen
Target Milestone:	z2	Keywords:	Automation, Triaged
Target Release:	17.1	Flags:	mtomaska: needinfo? (jamsmith)
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:
Fixed In Version:		Doc Type:	Known Issue
Doc Text:	If you use IPv6 to connect to instances during migration to the OVN mechanism driver, connection to the instances might be disrupted for up to several minutes when the ML2/OVS services are stopped. To avoid this, use IPv4 instead. + The router advertisement daemon `radvd` for IPv6 is stopped during migration to the OVN mechanism driver. While `radvd` is stopped, router advertisements are no longer broadcast. This broadcast interruption results in instance connection loss over IPv6. IPv6 communication is automatically restored once the new ML2/OVN services start. + To avoid the potential disruption, use IPv4 instead.	Story Points:	---
Clone Of:		Environment:
Last Closed:		Type:	Bug
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description Roman Safronov 2022-07-18 15:29:19 UTC

Description of problem:
Workload VM stops to respond to IPv6 address during OVN migration

Version-Release number of selected component (if applicable):
RHOS-17.0-RHEL-9-20220714.n.1

How reproducible:
happened on most osp17 ovs2ovn downstream jobs, 4 out of 5, except dvr2dvr 

Steps to Reproduce:
1.Deploy HA environment (3 controllers + 2 compute nodes) with ML2/OVS backend
2.Create a workload, internal network, router, security groups allowing ping/ping6 and ssh. Connect internal network to the external through the router.
3.Run infinite IPv6 ping to VM ipv6 addresses and IPv4 ping to the VM IPv4 address
4. Start ML2/OVS to ML2/OVN migration procedure according to the official documentation
  https://access.redhat.com/documentation/en-us/red_hat_openstack_platform/16.2/html/migrating_the_networking_service_to_the_ml2ovn_mechanism_driver/migrating-ml2ovs-to-ovn

Actual results:
The VM IPv4 address (FIP) responds to ping from the external network - this is CORRECT
The VM IPv6 address stops responding to ping6 from the external network, very high packet loss reported (see below) - BAD

--- 2001:db8:cafe:1:f816:3eff:fe91:7627 ping statistics ---
2356 packets transmitted, 186 received, 92.1053% packet loss, time 2407621ms



Expected results:
The VM IPv4 address (FIP) responds to ping from the external network
The VM IPv6 address responds to ping6 from the external network


Additional info:

Comment 20 Eran Kuris 2023-06-18 11:41:54 UTC

Raising the blocker flag as its an automation blocker