Red Hat Bugzilla – Bug 1475440
[DOCS] Packet Flow Docs can't be right, as TCP dumps on br0 don't show packets.
Last modified: 2017-09-10 20:26:26 EDT
Document URL: https://docs.openshift.com/container-platform/3.5/architecture/additional_concepts/sdn.html#sdn-packet-flow
Section Number and Name: Packet Flow
Describe the issue: If a TCP dump is taken on br0 and a pod tries to talk to another pod (no packets are captured).
Suggestions for improvement: We need to update the packet flows to accurately show how traffic moves from one interface to another so that troubleshooting on the correct interfaces can be done when there are performance and networking related issues.
This diagram is more up to date. Expect for the references vxlan0
Create the following KCS:
How to capture all OpenShift Pod traffic on a node's openvswitch br0 interface.
There are other ways to capture tcp data but this is one way using the mirror feature of ovs.
(In reply to Eric Rich from comment #0)
> Describe the issue: If a TCP dump is taken on br0 and a pod tries to talk to
> another pod (no packets are captured).
I think that's just an artifact of how Open vSwitch works; it must not be possible to use tcpdump on an Open vSwitch bridge. The documentation is correct about the logical flow of traffic.
(In reply to Ryan Howe from comment #1)
> This diagram is more up to date. Expect for the references vxlan0
There aren't really any differences between the two docs.
I guess the use of "vxlan0" (in both docs) is not quite accurate; it's referred to by that name in the OVS rules, but the actual network interface ends up being called "vxlan_sys_4789".
Thanks for that, Dan. I've made a PR:
Eric, as the reporter, would you say this fulfills this BZ? Is there something missing or is this not what you intended? Thanks.
Commit pushed to master at https://github.com/openshift/openshift-docs
Merge pull request #5018 from bfallonf/packetflow_1475440
Bug 1475440 Corrected vxlan naming info
Link to released docs: