R21xx-HP FlexFabric 11900 Layer 3 IP Services Configuration Guide

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Figure 16 ACS parameter sub-option value field
{ Service provider identifier sub-option value field—Contains the service provider identifier.
{ PXE server address sub-option value field—Contains the PXE server type that can only be 0,
the server number that indicates the number of PXE servers contained in the sub-option and
server IP addresses, as shown in Figure 17.
Figure 17 PXE server ad
dress sub-option value field
Relay agent option (Option 82)
Option 82 is the relay agent option. It records the location information of the DHCP client. When a
DHCP relay agent or DHCP snooping device receives a client's request, it adds Option 82 to the request
message and sends it to the server.
The administrator can use Option 82 to locate the DHCP client and further implement security control
and accounting. The DHCP server can use Option 82 to provide individual configuration policies for the
clients.
Option 82 can contain up to 255 sub-options and must have one sub-option at least. Option 82 supports
two sub-options: sub-option 1 (Circuit ID) and sub-option 2 (Remote ID).
Option 82 has no standard definition. Its padding formats vary with vendors.
Circuit ID has the following padding formats:
• String padding format—Contains a character string specified by the user.
• Normal padding format—Contains the VLAN ID and interface number of the interface that
received the client's request.
• Verbose padding format—Contains the access node identifier specified by the user, and the VLAN
ID, interface number and interface type of the interface that received the client's request.
Remote ID has the following padding formats:
• String padding format—Contains a character string specified by the user.
• Normal padding format—Contains the MAC address of the DHCP relay agent interface or the
MAC address of the DHCP snooping device that received the client's request.