Using Dhcp Snooping With Option 82 - HP 3500yl Series Access Security Manual

N o t e
HP Switch(config)# show dhcp-snooping
DHCP Snooping Information
DHCP Snooping
Enabled Vlans
Verify MAC
Option 82 untrusted policy : drop
Option 82 Insertion
Option 82 remote-id
Authorized Servers
---------------------
111.222.3.4
10 0 0 11
Figure 11-5. Example of Authorized Servers for DHCP Snooping

Using DHCP Snooping with Option 82

DHCP adds Option 82 (relay information option) to DHCP request packets
received on untrusted ports by default. (See "Configuring DHCP Relay" in the
Management and Configuration Guide for more information on Option 82.)
When DHCP is enabled globally and also enabled on a VLAN, and the switch
is acting as a DHCP relay, the settings for the DHCP relay Option 82 command
are ignored when snooping is controlling Option 82 insertion. Option 82
inserted in this manner allows the association of the client's lease with the
correct port, even when another device is acting as a DHCP relay or when the
server is on the same subnet as the client.
DHCP snooping only overrides the Option 82 settings on a VLAN that has
snooping enabled, not on VLANS without snooping enabled.
Configuring Advanced Threat Protection
: Yes
: 4
: No
: Yes
: subnet-ip
DHCP Snooping
11-9