You can reduce the impact of failures in your iSCSI network by ensuring that iSCSI connections are made through several NICs on the host or though network switching.
Oracle recommends using the normal IP configuration facilities to route connections to different ports on the Controller through different host NICs. For example, if the host has two NICs available for iSCSI connections to a Controller, you can set up routing to send all traffic to one port on each Controller through one NIC, and traffic to the other port on each Controller through the other NIC.
The best way to ensure that your iSCSI paths use different physical connections depends on factors such as the number of available NICs in the host and the existing configuration of your IP network. Oracle recommends using normal IP routing configuration techniques such as subnet configuration and explicit route configuration to distribute connections over multiple NICs. You can also use NIC bonding to provide redundancy on Ethernet connections between the host and the switch.