39InRow RC/RD/RP (600 mm) User’s Guide
DHCP response options
Each valid DHCP response contains options that provide the TCP/IP settings that the cooling unit needs
to operate on a network, and other information that affects the cooling unit’s operation.
Vendor specific information (option 43). The cooling unit uses this option in a DHCP response to
determine whether the DHCP response is valid. This option contains up to two APC-specific options in a
TAG/LEN/DATA format: the APC Cookie and the Boot Mode Transition.
• APC cookie. Tag 1, Len 4, Data “1APC”
Option 43 communicates to the cooling unit that a DHCP server is configured to service the
cooling unit. By default, this DHCP response option must contain the APC Cookie for the
cooling unit to accept the lease.
Following, in hexadecimal format, is an example of a Vendor Specific Information option that
contains the APC cookie:
Option 43 = 0x01 0x04 0x31 0x41 0x50 0x43
• Boot mode transition. Tag 2, Len 1, Data 1/2
This option 43 setting enables or disables Remain in DHCP & BOOTP mode after
accepting TCP/IP settings, which, by default, is disabled.
– A data value of 1 enables Remain in DHCP & BOOTP mode after accepting TCP/IP
settings. Whenever the cooling unit reboots, it will request its network assignment first from a
BOOTP server, and then, if necessary, from a DHCP server.
– A data value of 2 disables the Remain in DHCP & BOOTP mode after accepting TCP/IP
settings. The TCP/IP Configuration setting switches to DHCP when the cooling unit accepts
the DHCP response. Whenever the cooling unit reboots, it will request its network assignment
from a DHCP server only.
Following, in hexadecimal format, is an example of a Vendor Specific Information option that contains
the APC cookie and the disable Boot Mode Transition setting:
Option 43 = 0x01 0x04 0x31 0x41 0x50 0x43 0x02 0x01 0x01
To disable the requirement of an APC cookie, see “DHCP” on page38.