3Com 7757 Configuration Manual page 630

630 C 59: DHCP S
HAPTER
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C
NOOPING ONFIGURATION
Configuring the storage format of Option 82
The Switch 7750 supports the HEX or ASCII format for the Option 82 field.
Table 501 Configure a storage format for the Option 82 field
Operation
Enter system view
Configure a storage format
for the Option 82 field
The dhcp-snooping information format command applies only to the default
content of the Option 82 field. If you have configured the circuit ID or remote ID
sub-option, the format of the sub-option is ASCII, instead of the one specified
with the dhcp-snooping information format command.
Configuring the circuit ID sub-option
Table 502 Configure the circuit ID sub-option
Operation
Enter system view
Enter Ethernet port view
Configure the circuit ID
sub-option in Option 82
If you have configured a circuit ID with the vlan vlan-id argument specified,
■
and the other one without the argument in Ethernet port view, the former
circuit ID applies to the DHCP messages from the specified VLAN; while the
latter one applies to DHCP messages from other VLANs.
In a port aggregation group, you can use this command to configure the
■
primary and member ports respectively. When Option 82 is added, however,
the circuit ID sub-option is subject to the one configured on the primary port.
The circuit ID sub-option configured on a port will neither be synchronized in
■
the case of port aggregation.
Configuring the remote ID sub-option
You can configure the remote ID sub-option in system view or Ethernet port view:
In system view, the remote ID takes effect on all interfaces. You can configure
■
Option 82 as the system name of the device or any customized character string
in the ASCII format.
In Ethernet port view, the remote ID takes effect only on the current interface.
■
You can configure Option 82 as any customized character string in the ASCII
format for different VLANs. That is to say, you can add different configuration
rules for packets from different VLANs.
Command
system-view
dhcp-snooping information
format { hex | ascii }
Command
system-view
interface interface-type
interface-number
dhcp-snooping information
[ vlan vlan-id ] circuit-id
string string
Description
-
Optional
By default, the format is hex.
Description
-
-
Optional
By default, the circuit ID
sub-option contains the VLAN
ID and port index related to
the port that receives DHCP
request packets from DHCP
clients