Brocade Communications Systems Brocate Ethernet Access Switch 6910 - Manual (Page 272)

222 Brocade 6910 Ethernet Access Switch Configuration Guide
53-1002581-01
DHCP Snooping
10
• 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.
Example
This example sets the DHCP Snooping Information circuit-id suboption string.
Console(config)#interface ethernet 1/1
Console(config-if)#ip dhcp snooping information option circuit-id string 6910
Console(config-if)#
ip dhcp snooping trust
This command configures the specified interface as trusted. Use the no form to restore the default
setting.
Syntax
[no] ip dhcp snooping trust
Default Setting
All interfaces are untrusted
Command Mode
Interface Configuration (Ethernet, Port Channel)
Command Usage
• A trusted interface is an interface that is configured to receive only messages from within the
network. An untrusted interface is an interface that is configured to receive messages from
outside the network or fire wall.
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