H3C Technologies H3C S12500 Series Switches - Manual (Page 43)

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Self-defined options
Some options, such as Option 43, have no unified 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:
• Auto-Configuration Server (ACS) parameters, including the ACS URL, username, and password.
• Service provider identifier acquired by the customer premises equipment (CPE) from the DHCP
server and sent to the ACS for selecting vender-specific configurations and parameters.
• Preboot Execution Environment (PXE) server address for further obtaining the bootfile or other
control information from the PXE server.
1. Format of Option 43
Figure 17 Option 43 format
Network configuration parameters are carried in different sub-options of Option 43 as shown
in
Figure 17 . The sub-option fields are described as follows:
{
Sub-option type—Type of a sub-option. The field value can be 0x01, 0x02, or 0x80. 0x01
indicates an ACS parameter sub-option. 0x02 indicates a service provider identifier sub-option.
0x80 indicates a PXE server address sub-option.
{
Sub-option length—Length of a sub-option excluding the sub-option type and sub-option length
fields.
{
Sub-option value—Value of a sub-option. The value format varies with sub-options.
2. Format of the sub-option value field of Option 43
{
As shown in Figure 18 , the value field of the ACS parameter sub-option is filled in with variable
ACS URL, username, and password separated with a space (0x20) in between.
Figure 18 ACS parameter sub-option value field
{
The value field of the service provider identifier sub-option contains the service provider
identifier.
{
Figure 19 shows the format of the value field of the PXE server address sub-option. The value of
the PXE server type can only be 0. The server number field indicates the number of PXE servers
URL of ACS (variable)
User name of ACS (variable)
20
Password of ACS (variable)
20