can i do tcpdump on VMs and compute node

asked 2015-12-05 10:26:50 -0500

aksan gravatar image

I want to know whether VMs are communicating to each other thorugh VXLAN or not. Can i do tcpdump on VMs and hypervisor to verify that? What are my other options?

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answered 2015-12-06 00:43:29 -0500

Prateek K gravatar image

updated 2015-12-06 00:44:52 -0500

Why not, go ahead and use tcpdump on VM's as well. If you want to see the vxlan segmentation then tcpdump on VM wont help as the VM gets a clean packet without any segmentation.

As far as your question is concern you can use tcpdump on VM as well provided it has the package. If it doesn't have you can always download and install. A VM is nothing but a system running an OS of your choice.

Now as far as network debugging is concerned you can star seeing the OVS flows and bridges. It is OVS who is the commander here. He is the soul master here.

Some helpful commands to see the tables and ports of OVS:-

ovs-vsctl show

ovs-ofctl dump-flows <bridge>

If you also want to capture the packets having vxlan segmentation you can do so by having tcpdump on the tap devices where are there on the compute node. These tap devices are acutally the interfaces that you see on the VM's. To see tap device use this command:-

brctl show - To show the linux bridges.

Hope you will debug it and see how things are flowing. Let me know if there is anything else you want to debug

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Asked: 2015-12-05 10:26:50 -0500

Seen: 1,459 times

Last updated: Dec 06 '15