R21xx-HP FlexFabric 11900 Layer 3 IP Services Configuration Guide

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• Option 150—TFTP server IP address option. It specifies the TFTP server IP address to be assigned to
the client.
For more information about DHCP options, see RFC 2132 and RFC 3442.
Custom DHCP options
Some options, such as Option 43, Option 82, and Option 184, have no standard definitions in RFC
2132.
Vendor-specific option (Option 43)
DHCP servers and clients use Option 43 to exchange vendor-specific configuration information.
The DHCP client can obtain the following information through Option 43:
• Autoconfiguration server (ACS) parameters, including the ACS URL, username, and password.
• Service provider identifier, which is acquired by the CPE from the DHCP server and sent to the ACS
for selecting vender-specific configurations and parameters.
• Preboot execution environment (PXE) server address, which is used to obtain the boot file or other
control information from the PXE server.
1. Format of Option 43:
Figure 15 Option 43 format
Network configuration parameters are carried in different sub-options of Option 43 as shown
in Figure 15.
{ Sub-option type—The field value can be 0x01 (ACS parameter sub-option), 0x02 (service
provider identifier sub-option), or 0x80 (PXE server address sub-option).
{ Sub-option length—Excludes the sub-option type and sub-option length fields.
{ Sub-option value—The value format varies with sub-options.
2. Sub-option value field formats:
{ ACS parameter sub-option value field—Contains the ACS URL, username, and password
separated by spaces (0x20) as shown in Figure 16.