Chapter 9
| General Security Measures
DHCPv4 Snooping
– 339 –
Related Commands
ip dhcp snooping (331)
ip dhcp snooping trust (340)
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
no dhcp snooping information option circuit-id
string - An arbitrary string inserted into the circuit identifier field.
(Range: 1-32 characters)
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
■
access node identifier - ASCII string. Default is the MAC address of the
switch’s CPU. This field is set by the ip dhcp snooping information option
command,
■
eth - The second field is the fixed string “eth”
■
slot - The slot represents the stack unit for this system.
Table 59: 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
To Next Page
Loading...
Need help?
General