Description of problem:

While enabling ipv6 in MicroShift we are facing connectivity issues for almost all pods. When starting the system, without any applications and just MicroShift pods, some of them fail to reach the apiserver and see their packets being retransmitted without responses.

The underlying issue is that pods csi-snapshot-controller and service-ca (and always those two) fail to reach the apiserver because their addresses are deemed unreachable by the neighbor solicitation/advertisement messages in the host. The rest of the system pods (such as the router, for example) have no trouble reaching the apiserver. New pods (as if they were from an application) also have the same networking issues.

An example of this may be found in the attached tcpdump capture from MicroShift's start process. There is an additional file with information for the different IP addresses, routes and ovnk output for reference.

If the failing pods are manually pinged (using ping6) the neighbor solication/advertisement messages succeed on the second try and the neighbors are updated temporarily until they fail again. During that time the pod is able to reach apiserver without issues. Another tcpdump output is attached for this.

The latest changes in MicroShift are shared from a development branch for ipv6.

Version-Release number of selected component (if applicable):

4.17

How reproducible:

100%

Steps to Reproduce:

1. Install MicroShift from https://github.com/pacevedom/microshift/tree/USHIFT-3478

2. Configure MicroShift to use ipv6 clusterNetwork and serviceNetwork (see attachment with configuration)

3. Start MicroShift.

Actual results:

Connectivity issues between pods and apiserver.

Expected results:

Same behavior for all pods, being able to reach apiserver.

Additional info:

Please fill in the following template while reporting a bug and provide as much relevant information as possible. Doing so will give us the best chance to find a prompt resolution.

Affected Platforms:

Is it an

1. internal CI failure
2. customer issue / SD
3. internal RedHat testing failure

If it is an internal RedHat testing failure:

• Please share a kubeconfig or creds to a live cluster for the assignee to debug/troubleshoot along with reproducer steps (specially if it's a telco use case like ICNI, secondary bridges or BM+kubevirt).

If it is a CI failure:

• Did it happen in different CI lanes? If so please provide links to multiple failures with the same error instance
• Did it happen in both sdn and ovn jobs? If so please provide links to multiple failures with the same error instance
• Did it happen in other platforms (e.g. aws, azure, gcp, baremetal etc) ? If so please provide links to multiple failures with the same error instance
• When did the failure start happening? Please provide the UTC timestamp of the networking outage window from a sample failure run
• If it's a connectivity issue,
• What is the srcNode, srcIP and srcNamespace and srcPodName?
• What is the dstNode, dstIP and dstNamespace and dstPodName?
• What is the traffic path? (examples: pod2pod? pod2external?, pod2svc? pod2Node? etc)

If it is a customer / SD issue:

• Provide enough information in the bug description that Engineering doesn’t need to read the entire case history.
• Don’t presume that Engineering has access to Salesforce.
• Do presume that Engineering will access attachments through supportshell.
• Describe what each relevant attachment is intended to demonstrate (failed pods, log errors, OVS issues, etc).
• Referring to the attached must-gather, sosreport or other attachment, please provide the following details:
  • If the issue is in a customer namespace then provide a namespace inspect.
  • If it is a connectivity issue:
    • What is the srcNode, srcNamespace, srcPodName and srcPodIP?
    • What is the dstNode, dstNamespace, dstPodName and dstPodIP?
    • What is the traffic path? (examples: pod2pod? pod2external?, pod2svc? pod2Node? etc)
    • Please provide the UTC timestamp networking outage window from must-gather
    • Please provide tcpdump pcaps taken during the outage filtered based on the above provided src/dst IPs
  • If it is not a connectivity issue:
    • Describe the steps taken so far to analyze the logs from networking components (cluster-network-operator, OVNK, SDN, openvswitch, ovs-configure etc) and the actual component where the issue was seen based on the attached must-gather. Please attach snippets of relevant logs around the window when problem has happened if any.

• When showing the results from commands, include the entire command in the output.  
• For OCPBUGS in which the issue has been identified, label with “sbr-triaged”
• For OCPBUGS in which the issue has not been identified and needs Engineering help for root cause, label with “sbr-untriaged”
• Do not set the priority, that is owned by Engineering and will be set when the bug is evaluated
• Note: bugs that do not meet these minimum standards will be closed with label “SDN-Jira-template”
• For guidance on using this template please see
  OCPBUGS Template Training for Networking  components