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    Treating All Packets as Originating at Trusted Sources

    By default, the DHCP relay treats all packets destined for DHCP servers as if the packets originated at an untrusted source; if the packets have a gateway IP address (giaddr) of 0 and if option 82 information is present, these packets are dropped.

    • To enable the trust-all method on the DHCP relay:
      host1(config)#set dhcp relay trust-all

    In the trust-all method, the DHCP relay treats the packets as if they are from trusted sources and forwards the packets to the DHCP server. When you enable this command:

    • If the DHCP packets contain option 82 and a giaddr field of 0, the DHCP relay inserts its giaddr into the packets and then forwards the packets.
    • If the DHCP relay is configured to add option 82, it does not add an additional option 82 if one is already present in the DHCP packets.

    Published: 2014-08-20