When this variable is set to 'true', DHCP Snooping
will verify that the MAC address in the chaddr field
of the DHCP header matches the source MAC address in
all DHCP packets received on untrusted ports. When
this variable is set to 'false', DHCP Snooping will
omit this check. The value of this variable is
ignored when DHCP Snooping is disabled.