xStack DES-3800 Series Layer 3 Stackable Fast Ethernet Managed Switch CLI Manual
316
config dhcp_relay option_82 state
Purpose
Used to configure the state of DHCP relay agent information option 82
of the switch.
Syntax
config dhcp_relay option_82 state [enable | disable]
Description
This command is used to configure the state of DHCP relay agent
information option 82 of the switch. The relay agent will insert and
remove DHCP relay information (option 82 field) in messages between
DHCP server and client. When the relay agent receives the DHCP
request, it adds the option 82 information, and the IP address of the
relay agent (if the relay agent is configured), to the packet. Once the
option 82 information has been added to the packet it is sent on to the
DHCP server, which receives the packet, and if the server is capable of
option 82, it can implement policies like restricting the number of IP
addresses that can be assigned to a single remote ID or circuit ID. The
DHCP server will then echo the option 82 field in the DHCP reply. The
DHCP server unicasts the reply to the back to the relay agent if the
request was relayed to the server by the relay agent. The Switch then
verifies that it originally inserted the option 82 data. Finally, the relay
agent removes the option 82 field and forwards the packet to the switch
port that is connected to the DHCP client that sent the DHCP request.
Parameters
enable
– Choose this parameter to enable the addition of option 82
information to a packet.
disable-
Choose
disable
the relay agent from inserting and removing
DHCP relay information (option 82 field) in messages between DHCP
servers and clients, and the check and policy settings will have no
effect.
Restrictions
Only Administrator or Operator-level users can issue this command.
Example usage:
To configure DHCP relay option 82 state:
DES-3800:admin#config dhcp_relay option_82
state enable
Command: config dhcp_relay option_82 state
enable
Success.
DES-3800:admin#
config dhcp_relay option_82 check
Purpose
Used to configure the checking mechanism of DHCP relay agent information
option 82 of the switch.
Syntax
config dhcp_relay option_82 check [enable | disable]
Description
This command is used to configure the checking mechanism of
DHCP/BOOTP relay agent information option 82 of the switch. The relay
agent will check the validity of the packet’s option 82 field. If the switch
receives a packet that contains the option 82 field from a DHCP client, the
switch drops the packet because it is invalid. In packets received from DHCP
servers, the relay agent will drop invalid messages.
Parameters
enable
– Choose this parameter to enable validity checking of option 82
within packets.