To support DHCP based address assignment in L2 aggregation network, 7210 supports DHCP snooping. 7210 can copy packets designated to the standard UDP port for DHCP (port 67) to its control plane for inspection, this process is called DHCP snooping.
DHCP snooping can be performed in two directions:
From the client to the DHCP server (Discover or Request messages) to insert Option 82 information; For these applications, DHCP snooping must be enabled on the SAP toward the subscriber.
From the DHCP server (ACK messages), to remove the Option 82 field toward the client. For these applications, DHCP snooping must be enabled on both the SAP toward the network and the SAP toward the subscriber.