Chapter 9
| General Security Measures
DHCPv4 Snooping
– 292 –
ip dhcp snooping
information option
circuit-id
This command specifies DHCP Option 82 circuit-id suboption information. Use the
no
form to use the default settings.
Syntax
ip dhcp snooping information option circuit-id string
string |
{
tr101
{
node-identifier
{
ip
|
sysname
} |
no-vlan-field
}
no dhcp snooping information option circuit-id
[
tr101 no-vlan-field
]
string - An arbitrary string inserted into the circuit identifier field.
(Range: 1-32 characters)
tr101
node-identifier
- The remote ID generated by the switch is based on
TR-101 syntax (R-124, Access_Node_ID).
ip
- Specifies the switch’s IP address as the node identifier.
sysname
- Specifies the system name as the node identifier.
tr101
no-vlan-field
- Do not add “:VLAN” in TR101 field for untagged
packets.
Default Setting
VLAN-Unit-Port
Command Mode
Interface Configuration (Ethernet, Port Channel)
Command Usage
◆
DHCP provides a relay mechanism for sending information about the switch
and its DHCP clients to the DHCP server. DHCP Option 82 allows compatible
DHCP servers to use the information when assigning IP addresses, to set other
services or policies for clients. For more information of this process, refer to the
Command Usage section under the ip dhcp snooping information option
command.
◆
Option 82 information generated by the switch is based on TR-101 syntax as
shown below:
The circuit identifier used by this switch starts at sub-option1 and goes to the
end of the R-124 string. The R-124 string includes the following information:
■
sub-type - Distinguishes different types of circuit IDs.
■
sub-length - Length of the circuit ID type
Table 57: Option 82 information
82 3-69 1 1-67 x1 x2 x3 x4 x5 x63
opt82 opt-len sub-opt1 string-len R-124 string
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