Configuring multiple VMkernel Default Gateways

Until ESXi 6.0, there was only one default gateway for the entire TCP/IP stack. But sometimes you need different gateways for different VMkernel services, such as vMotion or iSCSI.

One option is to add some additional static routes, but this is not supported in ESXi 6.5 (KB 2001426 (https://kb.vmware.com/s/article/2001426)—Configuring static routes for vmkernel ports on an ESXi host).

Another option is to use multiple default gateways, and this is possible starting with ESXi 6.0 and thanks to the multiple TCP/IP stacks. Each TCP/IP stack represents a different network configuration, with specific network parameters, such as a different default gateway. 

You can set the different default gateway using the vSphere Web Client, in the Configure tab of each ESXi host. Just select the TCP/IP configuration menu (in the Networking section), choose one TCP/IP stack, and click on the Edit TCP/IP stack configuration icon:

For more information, see the vSphere 6.5 Networking guide (https://docs.vmware.com/en/VMware-vSphere/6.5/com.vmware.vsphere.networking.doc/GUID-44CAFD7C-6352-4993-A461-A27EE1C7D940.html).

It's also possible to create a custom TCP/IP stack, as described later.