Configuring Dhcp Snooping To Support Option 82 - 3Com 5500-EI PWR Install Manual

If an S5500-EI Ethernet switch is enabled with DHCP snooping, the clients connected to it cannot
dynamically obtain IP addresses through BOOTP.
You need to specify the ports connected to the valid DHCP servers as trusted to ensure that DHCP
clients can obtain valid IP addresses. The trusted port and the port connected to the DHCP client
must be in the same VLAN.
To enable DHCP snooping on an S5500-EI switch that belongs to an XRN fabric, do not configure
the ports connecting to the DHCP clients and DHCP server to belong to different units of the fabric;
otherwise, the switch cannot record DHCP snooping entries although the clients can obtain IP
addresses.
You are not recommended to configure both the DHCP snooping and selective Q-in-Q function on
the switch, which may result in the DHCP snooping to function abnormally.

Configuring DHCP Snooping to Support Option 82

Enable DHCP snooping and specify trusted ports on the switch before configuring DHCP snooping to
support Option 82.
Complete the following tasks to configure the DHCP snooping to support Option 82:
Enabling DHCP-snooping Option 82 support
Configuring a handling policy for DHCP packets with Option 82
Configuring the storage format of Option 82
Configuring the circuit ID sub-option
Configuring the remote ID sub-option
Configuring the padding format for Option 82
Enabling DHCP-snooping Option 82 support
Follow these steps to enable DHCP-snooping Option 82 support:
To do...
Enter system view
Enable DHCP-snooping Option
82 support
Task
Use the command...
system-view
dhcp-snooping information
enable
4-6
Remarks
Required
Optional
Optional
Optional
Optional
Optional
Remarks
—
Required
Disabled by default.