Specifications

CLI Management Guide
TigerAccess™ EE
330 SMC7824M/VSW
In case there is not a DHCP snooping option for a specific port, DHCP snooping switch
finds the snooping default option. If it exists, DHCP snooping switch sends a DHCP
server DHCP messages (Discover/Request) by replacing their options with the snooping
default option.
To specify a DHCP server default option, use the following command.
Command Mode Description
ip dhcp snooping default-option
code
<1-254> format NAME
Specifies a snooping default option format for a switch.
NAME: DHCP option format name
ip dhcp snooping default-option
code
<1-254> policy <keep |
replace>
Configures a policy against DHCP option belonging to
a DHCP message (default: replace)
keep: forwards a DHCP message to DHCP server
without any modification.
replace: deletes the DHCP message’s option and adds
the snooping default option if both of them are same.
However, if they are different each other,
replace op-
tion just adds the snooping default option.
no ip dhcp snooping default-
option code
<1-254>
Global
Removes the DHCP snooping default option for a
given port.
8.6.7.12 DHCP User Class ID
The switch can send the packets based on the policy or value of DHCP user class ID in
the DHCP message sent by the client. The user class ID on DHCP option 77 field identi-
fies the type of client sending the DHCP Discover/Request message.
If switch receives DHCP message from a client, it forwards the same packet to the server
with keep policy of DHCP option 77. Otherwise, it adds user class ID to the packet on the
configured port and forwards it to the server when the packet has no user class ID and
the policy of DHCP option 77 is replace. DHCP server can use DHCP option 77 field to
specify IP addresses of a particular pool based on user class ID of DHCP client.
To use DHCP option 77 fucntion, DHCP snooping must be enabled in the system of
switch. In case DHCP snooping is disabled in the system, the configured DHCP option 77
is automatically deleted.
To configure a user class id of DHCP option 77 on a specified port, use the following
command.
Command Mode Description
ip dhcp snooping user-class-id
port PORT class-id CLASS-ID
Global
Configures DHCP user class ID of DHCP option 77 per
port.
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