iSCSI multipathing will depend on the type of storage and the network topology in use. There are two methods:
Multipathing for iSCSI using port binding: This is achieved by having two VMkernel interfaces configured with an active adapter each, but no standby adapters. Once done, these VMkernel (vmk) interfaces should be bound to the software iSCSI adapter. Read the recipe Binding VMkernel interfaces to the software iSCSI adapter for more details.
Multipathing for iSCSI without port binding: Read the When not to use port binding section in the VMware KB: 2038869 for more details (http://kb.vmware.com/kb/2038869).
In this recipe, we will learn how to prepare the vSphere network for iSCSI multipathing by creating multiple VMkernel interfaces by using the same set of physical NICs in alternating active/unused pairs. This method is used to achieve iSCSI multipathing using the port binding method.