Unable to ping a local vxlan vmkernel interface

[walter12rom]

This issue is killing me. Am I unable to ping a local vmkernel interface? What's wrong with my life? The ping command works fine with all vmkernel interfaces on the default stack but it doesn't with vmk5, which is the one under vxlan stack. There is any NSX firewall between the hypervisor and local interfaces? I've seen issues related but they are always referring to ping an external host. Any idea? Thanks in advance!!

[junian_dani]

Hi,

Could you reach the default gateway of VTEP vmkernel? In your case, it will be 10.0.0.254.

[bayupw]

VXLAN uses separate TCP/IP stack or netstack instances.

If you check it out through the esxcli network ip netstack get command, you will see that there should be at least two netstacks - defaultTCPipStack and VXLAN. 

As the VTEP VXLAN is a vmkernel, use the vmkping command as opposed to regular ping command and specify the vxlan stack using below command

     vmkping ++netstack=vxlan <vmknic IP> -d -s <packet size>

See this KB: Testing VMkernel network connectivity with the vmkping command (1003728) | VMware KB

Make sure your switches is configured with at least 1600 MTU (depends on the MTU that you have configured during VXLAN configuration, 1600 is the default)

To validate this, ping using MTU smaller than 1500 e.g. 1470 then try again using MTU highter thatn 1500 e.g. 1570.

If the ping works with the smaller (1470) size, but not 1570, then you have MTU issue in your physical switch.

[walter12rom]

No Junian Dani I can't, I can't even reach my own IP address.

[walter12rom · Accepted solution]

I had previously tried a shot with this command vmkping -I vmk5 10.0.0.2 but it didn't work. It seems like the only way to use vxlan stack and vxlan vmkernel interface is vmkping ++netstack=vxlan 10.0.0.2 -d -s 1600. This command was successful.

PING 10.0.0.2 (10.0.0.2): 1600 data bytes

1608 bytes from 10.0.0.2: icmp_seq=0 ttl=64 time=0.187 ms

1608 bytes from 10.0.0.2: icmp_seq=1 ttl=64 time=0.180 ms

1608 bytes from 10.0.0.2: icmp_seq=2 ttl=64 time=0.179 ms

So my first problem is solved now. Now I have to stay working because I'm still unable to ping my second host. Thanks guys!