CTC Union GSW-3420FM, User Manual

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(config)# ip dhcp snooping
(config)# no ip dhcp snooping
Port Setting :
(config-if)# ip dhcp snooping trust
(config-if)# no ip dhcp snooping trust
Status by Web :
[Monitor] -> [DHCP] -> [Snooping Table]
Click “
?
” at this web page to get details of the settings.
Status by Command :
# clear ip dhcp snooping statistics [ interface <port_type_list> ]
# show ip dhcp snooping [ table | interface <port_type_list> ]
2. DHCP Relay
DHCP Relay is used to forward and to transfer DHCP messages between the
clients and the server when they are not on the same subnet domain.
The DHCP option 82 enables a DHCP relay agent to insert specific information
into a DHCP request packets when forwarding client DHCP packets to a DHCP
server and remove the specific information from a DHCP reply packets when
forwarding server DHCP packets to a DHCP client. The DHCP server can use
this information to implement IP address or other assignment policies.
Specifically the option works by setting two sub-options: Circuit ID (option 1) and
Remote ID (option2). The Circuit ID sub-option is supposed to include
information specific to which circuit the request came in on. The Remote ID
sub-option was designed to carry information relating to the remote host end of
the circuit.
The definition of Circuit ID in the switch is 4 bytes in length and the format is
"vlan_id" "module_id" "port_no". The parameter of "vlan_id" is the first two bytes
represent the VLAN ID. The parameter of "module_id" is the third byte for the
module ID (in standalone switch it always equal 0, in stackable switch it means
switch ID). The parameter of "port_no" is the fourth byte and it means the port
number.
The Remote ID is 6 bytes in length, and the value is equal the DHCP relay
agents MAC address.
Configuration by Web :
Enable/Disable, VLAN Range :
[Configuration] -> [DHCP] -> [Relay]
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