enable dhcp_relay
config dhcp_relay hops 4 time 0
config dhcp_relay option_82 state enable
config dhcp_relay option_82 check disable
config dhcp_relay option_82 policy replace
config dhcp_relay option_82 circuit_id default
config dhcp_relay option_82 remote_id default
config dhcp_relay add ipif System АААА
config dhcp_relay add ipif System ВВВВ

disable dhcp_local_relay
config dhcp_local_relay option_82 circuit_id default
config dhcp_local_relay option_82 remote_id default
config dhcp_local_relay option_82 ports 1-10 policy keep

config dhcp_relay option_82 check enable

config dhcp_relay option_82 policy keep

config dhcp_relay delete ipif System АААА
config dhcp_relay delete ipif System ВВВВ
config dhcp_relay add vlanid 1004 АААА
config dhcp_relay add vlanid 1004 ВВВВ

This is a flag (check) whether the relay agent check the option82 in the packet. If this status is enabled, the relay agent will drop the packet which contains option82.

This option (policy) takes effect only when the check status is disabled. The relay agent does this operation because the packet cannot contain two option82. The operation of different policies listed at Table:

Policy                The packet contains option82                                              The packet dose not contain option82                       
Replace               Use own option82 replace the old option 82 in the packet                  Use own option82 replace the old option82 in the packet
Drop                  Drop the packet                                                           Use own option82 replace the old option82 in the packet
Keep                  Keep the old option82                                                     Use own option82 replace the old option82 in the packet