Brocade 6910 Ethernet Access Switch Configuration Guide (Supporting R2.2.0.0) - Manual (Page 273)

Brocade 6910 Ethernet Access Switch Configuration Guide 217
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10
DHCP Snooping
ip dhcp snooping information option circuit-id
This command enables the use of DHCP Option 82 information circuit-id suboption. Use the no
form to disable this feature.
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
Disabled
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.
• port - The port which received the DHCP request. If the packet arrives over a trunk, the
value is the ifIndex of the trunk.
• vlan - Tag of the VLAN which received the DHCP request.
Note that the sub-type and sub-length fields can be enabled or disabled using the ip dhcp
snooping information option command.
• The ip dhcp snooping information option circuit-id command can be used to modify the default
settings described above.
TABLE 54 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