Dhcp Client Operation With Other Features; Configure The System For User Port Stacking (Option 230) - Dell Force10 Z9000 Configuration Manual

DHCP Client Operation with Other Features

The DHCP client operates with other Dell Networking OS features, as the following describes.
Stacking
The DHCP client daemon runs only on the master unit and handles all DHCP packet transactions. It periodically synchronizes the
lease file with the standby unit.
When a stack failover occurs, the new master requires the same DHCP server-assigned IP address on DHCP client interfaces. The
new master reinitiates a DHCP packet transaction by sending a DHCP discovery packet on nonbound interfaces.
Virtual Link Trunking (VLT)
A DHCP client is not supported on VLT interfaces.
VLAN and Port Channels
DHCP client configuration and behavior are the same on Virtual LAN (VLAN) and port-channel (LAG) interfaces as on a physical
interface.
DHCP Snooping
A DHCP client can run on a switch simultaneously with the DHCP snooping feature as follows:
• If you enable DHCP snooping globally on a switch and you enable a DHCP client on an interface, the trust port, source MAC
address, and snooping table validations are not performed on the interface by DHCP snooping for packets destined to the DHCP
client daemon.
The following criteria determine packets destined for the DHCP client:
– DHCP is enabled on the interface.
– The user data protocol (UDP) destination port in the packet is 68.
– The chaddr (change address) in the DHCP header of the packet is the same as the interface's MAC address.
• An entry in the DHCP snooping table is not added for a DHCP client interface.
DHCP Server
A switch can operate as a DHCP client and a DHCP server. DHCP client interfaces cannot acquire a dynamic IP address from the
DHCP server running on the switch. Acquire a dynamic IP address from another DHCP server.
Virtual Router Redundancy Protocol (VRRP)
Do not enable the DHCP client on an interface and set the priority to 255 or assign the same DHCP interface IP address to a VRRP
virtual group. Doing so guarantees that this router becomes the VRRP group owner.
To use the router as the VRRP owner, if you enable a DHCP client on an interface that is added to a VRRP group, assign a priority
less than 255 but higher than any other priority assigned in the group.

Configure the System for User Port Stacking (Option 230)

Set the stacking-option variable to provide stack-port detail on the DHCP server when you set the DHCP offer. A stack can be
formed when the units are connected.
Option 230 is the option for user port stacking. Use it to create up to eight stack groups. Define the configuration parameters on the
DHCP server for each chassis based on the chassis MAC address. Configure the following parameters:
• unit number
• priority
• stack group ID
Dynamic Host Configuration Protocol (DHCP)
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