There are two methods to achieve path redundancy if using iSCSI (RFC3720) in clustered Data ONTAP: by using ifgrps to aggregate more than one physical port in partnership with an LACP-enabled switch, or by configuring hosts to use MPIO over multiple distinct physical links. Both of these methods allow a storage controller and host to use aggregated bandwidth and both can survive the failure of one of the paths from host to storage controller. However, MPIO is already a requirement for using block storage with clustered Data ONTAP, and using MPIO has the further advantage of no additional switch configuration or port trunking configuration being required. Also, using an ifgrp for path management when using iSCSI is not supported, again, you will want to use MPIO with iSCSI. But, using an ifgrp as a port for an iSCSI LIF is supported.