Description of problem:
Bare Metal UPI cluster

Nodes lose communication with other nodes and this affects the pod communication on these nodes as well. This issue can be fixed with an OVN rebuild on the nodes db that are hitting the issue but eventually the nodes will degrade again and lose communication again. Note despite an OVN Rebuild fixing the issue temporarily Host Networking is set to True so it's using the kernel routing table. This cluster does not use ipsec
Version-Release number of selected component (if applicable):
4.14.7, 4.14.30
How reproducible:
Can't reproduce locally but reproducible and repeatedly occurring in customer environment
Steps to Reproduce:

identify a host node who's pods can't be reached from other hosts in default namespaces ( tested via openshift-dns). observe curls to that peer pod consistently timeout. TCPdumps to target pod observe that packets are arriving and are acknowledged, but never route back to the client pod successfully. (SYN/ACK seen at pod network layer, not at geneve; so dropped before hitting geneve tunnel).

Actual results:
Nodes will repeatedly degrade and lose communication despite fixing the issue with a ovn db rebuild (db rebuild only provides days of respite, no permanent resolve).
 

Expected results:
Nodes should not be losing communication and even if they did it should not happen repeatedly
Additional info:
What's been tried so far
========================

• Multiple OVN rebuilds on different nodes (works but node will eventually hit issue again)

• Flushing the conntrack (Doesn't work)

• Restarting nodes (doesn't work)

Data gathered
=============

• Tcpdump from all interfaces for dns-pods going to port 7777 (to segregate traffic)

• ovnkube-trace

• SOSreports of two nodes having communication issues before an OVN rebuild

• SOSreports of two nodes having communication issues after an OVN rebuild

• OVS trace dumps of br-int and br-ex
  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