You should be aware of important concepts that are required to understand how Data ONTAP implements an iSCSI network.
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What iSCSI is
The iSCSI protocol is a licensed service on the storage system that enables you to transfer block data to hosts using the SCSI protocol over TCP/IP. The iSCSI protocol standard is defined by RFC 3270.
What iSCSI nodes are
In an iSCSI network, there are two types of nodes: targets and initiators. Targets are storage systems, and initiators are hosts. Switches, routers, and ports are TCP/IP devices only, and are not iSCSI nodes.
How the storage system checks initiator node names
The storage system checks the format of the initiator node name at session login time. If the initiator node name does not comply with storage system node name requirements, the storage system rejects the session.
Default port for iSCSI
The iSCSI protocol is configured in Data ONTAP to use TCP port number 3260.
What target portal groups are
A target portal group is a set of network portals within an iSCSI node over which an iSCSI session is conducted.
What iSNS is
The Internet Storage Name Service (iSNS) is a protocol that enables automated discovery and management of iSCSI devices on a TCP/IP storage network. An iSNS server maintains information about active iSCSI devices on the network, including their IP addresses, iSCSI node names, and portal groups.
What CHAP authentication is
The Challenge Handshake Authentication Protocol (CHAP) enables authenticated communication between iSCSI initiators and targets. When you use CHAP authentication, you define CHAP user names and passwords on both the initiator and the storage system.
How iSCSI communication sessions work
During an iSCSI session, the initiator and the target communicate over their standard Ethernet interfaces, unless the host has an iSCSI HBA or a CNA.
How iSCSI works with
HA pairs
HA pairs provide high availability because one system in the HA pair can take over if its partner fails. During failover, the working system assumes the IP addresses of the failed partner and can continue to support iSCSI LUNs.
