Troubleshoot VXLAN, VTEP, and VNI configuration and connectivity
There are a couple different ways to test connectivity for these components. I like to start out by testing connectivity using the GUI first, then command line second. Once these components are configured, you can test connectivity via the vSphere Web Client by navigating to Networking & Security -> Logical Switches and double click the logical switch to test connectivity.
From there, click on the Monitor tab and then then select Hosts -> Ping. you will be presented with the following screen. Select both the Source and Destination host and leave VXLAN standard as the size of the test packet. By default VXLAN needs a size of 1600 MTU. Go ahead and click start test, and the test will send and receive 3 packets and display the latency and whether or not the test was successful.
You can also use the command line to test connectivity. Log into the two hosts that you would like to test connectivity to and from via SSH, and run the following commands. the -s will specify the size of the packet, remember VXLAN requires 1600 MTU so we will test a jumbo frame slightly larger than 1500 MTU (You can’t do 1600 as the header information is about 28k). You can find all of your vmkernel information under Networking & Security -> Installation -> Logical Network Preparation. Notice I have specified the interface vmk3.
~ # vmkping ++netstack=vxlan -s 1570 -d -I vmk3 192.168.250.52 PING 192.168.250.52 (192.168.250.52): 1570 data bytes 1578 bytes from 192.168.250.52: icmp_seq=0 ttl=64 time=2.017 ms 1578 bytes from 192.168.250.52: icmp_seq=1 ttl=64 time=3.062 ms 1578 bytes from 192.168.250.52: icmp_seq=2 ttl=64 time=0.962 ms
As you can see, my communication is successful. If the communication between the two hosts is unsuccessful you need to start troubleshooting why. Again, it’s important to remember that you need to have jumbo frames enabled end to end with a size of 1600 minimum. You can confirm that this is the issue if you run a vmkping with a smaller packet size, as shown below. If the below ping works with the smaller (1470) size, but not 1570, then you have a jumbo frame issue.
~ # vmkping ++netstack=vxlan -s 1470 -d -I vmk3 192.168.250.52 PING 192.168.250.52 (192.168.250.52): 1470 data bytes 1478 bytes from 192.168.250.52: icmp_seq=0 ttl=64 time=1.258 ms 1478 bytes from 192.168.250.52: icmp_seq=1 ttl=64 time=1.021 ms 1478 bytes from 192.168.250.52: icmp_seq=2 ttl=64 time=1.420 ms
You also want to ensure that the VLAN is configured correctly. As show in the previous image under Networking & Security -> Installation -> Logical Network Preparation you will see my VLAN is 0. Make sure that they are both on the same VLAN, and that the physical network is trunking those VLANs. If everything looks good ok here, check out the following articles to ensure that everything is configured correctly.
Manage and Report on a Logical Switch using CLI
Manage and Report on NSX installation using CLI
Manage and report on NSX infrastructure using CLI