The iSeries™ iSCSI attached server solution provides an integrated DHCP server. The server is used to deploy boot parameters to the hosted system iSCSI HBA when the Dynamically delivered to the remote system via DHCP option is specified in the i5/OS™ remote system configuration object and AUTO or DHCP mode is specified in the hosted server iSCSI HBA.
The integrated DHCP server is not a general purpose server. It is intended to exclusively deploy boot parameters to the hosted server iSCSI HBA. The server is automatically configured with the parameters provided in the remote system configuration when an network server description (NWSD) is varied on.
The DHCP server will only respond to the hosted server's iSCSI HBA DHCP client. All of the iSCSI HBA DHCP client requests use an IBM® defined vendor id. The server is programmed to respond to requests that use the default vendor id. Any other requests from other devices in the network will be ignored by the DHCP server.
Providing the MAC addresses of the hosted server iSCSI HBAs in the remote system configuration object is very important. In addition to the vendor id previously described, the integrated DHCP server uses the MAC address to properly deploy boot parameters. MAC address is part of the specific scope required to ensure proper parameter deployment.
The scope provided by the vendor id and MAC address can be changed. While
this is considered an advanced function, provisions have been put in place
to allow the advanced and sophisticated users to more specifically configure
this setting, when required. The default vendor id can be configured to other
values. Configuration screens are available in the hosted server iSCSI HBA
adapter CTRL-Q set up utility and the corresponding remote system configuration
object. This advanced function is compliant with the RFC 2132 specification.
For more details on advanced configurations see iSCSI install read me first
When an incoming DHCP request is received by the integrated DHCP server and all of the required scope is matched, the integrated DHCP server provides to the DHCP client the IP addresses for the boot target device. The boot target device is the network server host adapter (NWSH) where the boot virtual disk is configured. The server also provides the IP address for the initiator or DHCP client. The initiator is the iSCSI HBA in the hosted server that will be used to boot over iSCSI.
In addition, the integrated DHCP server provides the globally unique iSCSI Qualified Names (IQNs) that represent the target and initiator devices to the hosted system iSCSI HBA.
Both of these sets of IP addresses and IQNs are in the iSeries configuration objects used to define the hosted server. The target IP address is defined in the NWSH object. The initiator IP address and initiator IQN are defined in the remote system configuration object. The target IQN is automatically configured and defined in the NWSD object. For more information about these objects refer to Network server description.
The integrated DHCP server is a key and integral component when implementing hot spares. The DHCP boot mode enables automatic deployment of the required parameters defined in the iSeries software objects, eliminating the need to manually configure a server when boot parameters (IP addresses and IQNs) change.
