IP Routing Features
Configuring DHCP Relay
drop: Configures the routing switch to unconditionally drop any client DHCP packet received with existing Option 82 field(s). This means that such packets will not be forwarded. Use this option where access to the routing switch by untrusted clients is possible.
If the routing switch receives a client DHCP packet without an Option 82 field, it adds an Option 82 field to the client and forwards the packet. The added Option 82 field includes the switch circuit ID (inbound port number*) associated with the client DHCP packet, and the switch remote ID. The default switch remote ID is the MAC address of the switch on which the packet was received from the client. To use the incoming VLAN’s IP address instead of the switch MAC address for the remote ID, use the IP option (below).
keep: For any client DHCP packet received with existing Option 82 field(s), configures the routing switch to forward the packet
*For more on identifying the inbound port number, refer to “Circuit ID” in the bulleted list on page <zBlue>33.
[ validate ]: This option operates when the routing switch is configured with append, replace, or drop as a forwarding policy. With validate enabled, the routing switch applies stricter rules to an incoming Option 82 server response to determine whether to forward or drop the response. For more information, refer to “Validation of Server Response Packets” on page 7 36.
[ ip mac ]
This option specifies the remote ID suboption the routing switch will use in Option 82 fields added or appended to DHCP client packets. The choice of type depends on how you want to define DHCP policy areas in the client requests sent to the DHCP server. (Refer to “Option 82 Field Content” on page
ip: Specifies the IP address of the VLAN on which the client DHCP packet enters the switch.
mac: Specifies the routing switch’s MAC address. (The MAC address used is the same MAC address that is assigned to all VLANs configured on the routing switch.) This is the default setting.
Notes on Default Remote ID Selection: Executing the Option 82 command without specifying either ip or mac configures the remote ID as the MAC address of the switch on which the packet was received from the client. The command options for viewing the routing switch MAC address are listed at the end of the “Remote ID” description that begins on page <zBlue>32.