6 Replies Latest reply on Dec 6, 2018 1:52 PM by aj800

    ESXi 6.5 - vSphere Distributed Switch VLAN Trunked and MTU Supported Status warnings

    aj800 Novice

      After downloading, staging and applying patches to the first ESXi host in a vSphere 6.5 host cluster, the host, after exiting Maintenance Mode, showed 2 triggered alarms:
      vSphere Distributed Switch VLAN trunked status
      vSphere Distributed Switch MTU supported status

      Upon further review of vDS settings and details, selecting vDS --> Monitor Tab --> Heath Tab, there was a warning of 10 issues (started at 12, but apparently the 'Out of sync' issue was resolved): 'Unsupported VLAN' and 'MTU Mismatch' for each of the 5 hosts. When selected each host, the panel below shows 4 of 6 vmnics as "unsupported" but there are VMs running on this host that don not seem to have any connectivity issues (at the moment).  How do I resolve this? We are currently running a vDS of 5.5 (we have not upgraded yet and I didn't notice until after the patching was completed), although the vCenter (VCSA) and ESXi hosts are at 6.5.0. This is in a production environment and I would need to correct this as soon as possible so I may continue with the patching to address a critical vulnerability.  Any help is appreciated.

        • 1. Re: ESXi 6.5 - vSphere Distributed Switch VLAN Trunked and MTU Supported Status warnings
          sk84 Hot Shot
          vExpert

          What exactly does it show when you select a host from the list? It should normally show you the VLAN ID that is not supported. The error usually occurs if you have configured a dvPortgroup with a VLAN ID that does not exist on the physical switch port of an uplink. This usually triggers also the MTU warning for the same VLAN ID.

          • 2. Re: ESXi 6.5 - vSphere Distributed Switch VLAN Trunked and MTU Supported Status warnings
            aj800 Novice

            From the list when you select a host (vDS --> Monitor --> Health --> VLAN Tab), it shows under the "VLAN Trunk" column a value of "0" and under the "VLAN Status" column a value of "Not supported" for 4 of the 6 vmnics listed.  The other 2 show "Supported".  The vDS port groups are not assigned Vlan IDs/numbers.

             

            For the MTU tab, it shows "Not supported" for the same 4/6 vmnics.

             

            Is this because the vDS is running 5.5, still, in the 6.5.0 environment, and would upgrading first correct this?

            • 3. Re: ESXi 6.5 - vSphere Distributed Switch VLAN Trunked and MTU Supported Status warnings
              sk84 Hot Shot
              vExpert

              Okay. Normally there is a VLAN ID instead of 0, which is missing on the physical switch port. For example: You have created a port group with VLAN ID 10, but VLAN 10 is not configured on the switchports of some uplinks. In this case, the number 10 would be there.

               

              If this is 0, it usually means that you have portgroups where VLAN is set to "none". So the dvSwitch sends the packets from these port groups untagged to the physical switch port. The dvSwitch healthchecks check this, too, but if there is no Native VLAN configured on a trunk port of the physical switch, these frames are dropped and the healthcheck warns about this.

               

              I therefore suspect that the switchport configuration of some uplinks is different. Especially the Native VLAN configuration.

              • 4. Re: ESXi 6.5 - vSphere Distributed Switch VLAN Trunked and MTU Supported Status warnings
                aj800 Novice

                The Native VLAN on the physical switch (HP Flex10) shows as VLAN 1, which I suppose is the default setting.  There are 3 Vlans, including VLAN 1 going to this environment.  So what is the fix for this if that's the case?

                • 5. Re: ESXi 6.5 - vSphere Distributed Switch VLAN Trunked and MTU Supported Status warnings
                  sk84 Hot Shot
                  vExpert

                  Unfortunately, I'm not familiar with HP switches, especially the Virtual Connect modules. With our Cisco network infrastructure, I simply created a VLAN as a native VLAN on each switchport where an ESXi uplink is connected and the problem was solved. We have no untagged traffic in our infrastructure, so using a "dummy" native vlan was an acceptable workaround.

                   

                  With Cisco it would be:

                   

                  switch# conf t

                  switch(config)# vlan 123

                  switch(config-vlan)# name VMWARE-NATIVE-DUMMY

                  switch(config-vlan)# exit

                  switch(config)# int Ethernet1/35

                  switch(config-if)# switchport trunk allowed vlan add 123

                  switch(config-if)# switchport trunk native vlan 123

                  switch(config-if)# end

                  switch# wr

                  (Interface must be changed)

                  • 6. Re: ESXi 6.5 - vSphere Distributed Switch VLAN Trunked and MTU Supported Status warnings
                    aj800 Novice

                    So, I haven't gotten to the network settings changes or analysis yet since it's a blade server and I'll have to investigate how that was and should be set up vs. how it current is.  I also wanted to upgrade the vDS to see if that made any difference...

                     

                    So I upgraded the vDS from version 5.5.0 to 6.5.0, hoping that might clear something up compatibility-wise.  It did not.  Now, of the 5-host cluster, 3 of the other hosts now show the same Critical Alerts as the original one I had the issue with, but oddly, one of them does not.  That host is running the same OS as the others (minus the one host I had patched) and appears to be configured the same way also.  So now 4 of the 5 hosts show the Alert.  I'll have to review the network settings on both sides but if you or anyone else has any input or recommendations beyond what's already been recommended here, I'm all ears.  Thanks.