How to resolve Out-of-Sync dvSwitch Issue?

 Symptoms

• You see this banner alert in the Networking view:

The vNetwork Distributed Switch configuration on some hosts differed from that of the vCenter Server.

• When viewing a list of hosts attached to the distributed switch, or from the manage hosts wizard under the vDS Status column, you see a yellow warning icon and the message:

Out of sync

• You have recently rebooted one or more ESX/ESXi hosts.
• You have recently restarted the vCenter Server service, or rebooted the vCenter Server.

Cause

Although vNetwork Distributed Switches are a component within vCenter server, most of the switch's underlying functionality is handled at the ESX/ESXi host level. As such, relevant vDS configuration information is stored locally on the host and are periodically synchronized with vCenter Server.

If network connectivity is interrupted between the vCenter Server and one or more hosts, a synchronization interval may be missed resulting in this alert being displayed. This type of interruption can occur during vCenter Service restarts, vCenter Server reboots as well as ESX/ESXi host reboots or network maintenance.

Resolution

If vCenter Server or an ESX/ESXi host has been recently restarted, this message is benign and can be safely ignored. Within several minutes, the host's vNetwork Distributed Switch information should synchronize with vCenter Server, and the warning clears.

 

To manually synchronize the host vDS information from the vSphere Client:

1. In the Inventory section, click Home > Networking. 
2. Select the vDS displaying the alert and then click the Hosts tab.
3. Right-click the host displaying the Out of sync warning and then click Rectify vNetwork Distributed Switch Host.

To manually synchronize the host vDS information from the vSphere web client (vSphere 5.5):

1. Click affected host from the Host inventory tab.
2. Click the Manage tab.
3. Click Networking.
4. Click Virtual Switches.
5. Click the out-of-sync Virtual Distributed Switch in the list of virtual switches.
6. A new button with an icon of a server and a red icon of a switch appears, click this button to synchronize the referenced distributed virtual switch.
   
   The synchronization task appears in the Running Tasks window. You can monitor the progress of the synchronization there.

If vCenter Server or an ESX/ESXi host has not been restarted recently and the alert does not clear on it's own, there may be other problems in the environment inhibiting the synchronization of vDS data. If the problem persists, Ensure there are no intermittent network connectivity issues with the ESX/ESXi host or to vCenter Server.

In my case i was not able to resolve  this issue even after following the above solution then finally i removed the host from dvSwitch and added it again and then finally issue was resolved.

 Source:-

http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=2042692&src=vmw_so_vex_ragga_1012