Dell PowerConnect FCS624S Configuration Guide - Page 1397

DHCP relay agent information (DHCP Option 82) 39 As illustrated in Figure 178, the DHCP relay agent (the PowerConnect switch), inserts DHCP option 82 attributes when relaying a DHCP request packet to a DHCP server. FIGURE 178 DHCP Option 82 attributes added to the DHCP packet DHCP client request packet DHCP Snooping + option 82 option Untrusted 82 Trusted DHCP Client Switch DHCP Relay Agent DHCP Server As illustrated in Figure 179, the PowerConnect switch deletes DHCP option 82 attributes before forwarding a server reply packet back to a DHCP client. FIGURE 179 DHCP Option 82 attributes removed from the DHCP packet DHCP Snooping option 82 DHCP Server reply packet option Untrusted 82 Trusted DHCP Client Switch DHCP Relay Agent DHCP Server The DHCP option 82 insertion/deletion feature is available only when DHCP snooping is enabled for the client/server ports. Configuration notes • DHCP snooping and DHCP option 82 are supported on a per-VLAN basis. • DHCP option 82 follows the same configuration rules and limitations as for DHCP snooping. For more information, refer to "Configuration notes and feature limitations" on page 1351. DHCP Option 82 sub-options The Dell implementation of DHCP Option 82 supports the following sub-options: • Sub-Option 1 - Circuit ID • Sub-Option 2 - Remote ID • Sub-Option 6 - Subscriber ID These sub-options are described in the following sections. PowerConnect B-Series FCX Configuration Guide 53-1002266-01 1355