Software and dependent hardware iSCSI adapters depend on VMkernel networking. If you use the software or dependent hardware iSCSI adapters, you must configure connections for the traffic between the iSCSI component and the physical network adapters.

Configuring the network connection involves creating a virtual VMkernel interface for each physical network adapter and associating the interface with an appropriate iSCSI adapter.

If your host has more than one physical network adapter for software and dependent hardware iSCSI, use the adapters for multipathing.

You can connect the software iSCSI adapter with any physical NICs available on your host. The dependent iSCSI adapters must be connected only with their own physical NICs.

Note

Physical NICs must be on the same subnet as the iSCSI storage system they connect to.

Networking with iSCSI
Networking with iSCSI.

The iSCSI adapter and physical NIC connect through a virtual VMkernel adapter, also called virtual network adapter or VMkernel port. You create a VMkernel adapter (vmk) on a vSphere switch (vSwitch) using 1:1 mapping between each virtual and physical network adapter.

One way to achieve the 1:1 mapping when you have multiple NICs, is to designate a separate vSphere switch for each virtual-to-physical adapter pair. The following examples show configurations that use vSphere standard switches, but you can use distributed switches as well. For more information about vSphere distributed switches, see the vSphere Networking documentation.

1:1 adapter mapping on separate vSphere standard switches
The graphic shows NIC and port pairs connected through separate vSwitches.
Note

If you use separate vSphere switches, you must connect them to different IP subnets. Otherwise, VMkernel adapters might experience connectivity problems and the host will fail to discover iSCSI LUNs.

An alternative is to add all NICs and VMkernel adapters to a single vSphere standard switch. In this case, you must override the default network setup and make sure that each VMkernel adapter maps to only one corresponding active physical adapter.

1:1 adapter mapping on a single vSphere standard switch
The graphic shows two physical NIC and iSCSI port pairs connected through a single vSwitch.

The following table summarises the iSCSI networking configuration discussed in this topic.

Networking configuration for iSCSI

iSCSI Adapters

VMkernel Adapters (Ports)

Physical Adapters (NICs)

Software iSCSI

vmhba32

vmk1

vmnic1

vmk2

vmnic2

Dependent Hardware iSCSI

vmhba33

vmk1

vmnic1

vmhba34

vmk2

vmnic2