Reference Guide

• 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.
DHCP Client on a Management Interface
These conditions apply when you enable a management interface to operate as a DHCP client.
• The management default route is added with the gateway as the router IP address received in the DHCP ACK
packet. It is required to send and receive traffic to and from other subnets on the external network. The route is
added irrespective when the DHCP client and server are in the same or different subnets. The management
default route is deleted if the management IP address is released like other DHCP client management routes.
• ip route for 0.0.0.0 takes precedence if it is present or added later.
• Management routes added by a DHCP client display with Route Source as DHCP in the show ip
management route
and show ip management-route dynamic command output.
• Management routes added by DHCP are automatically reinstalled if you configure a static IP route with the ip
route command that replaces a management route added by the DHCP client. If you remove the statically
configured IP route using the
no ip route command, the management route is reinstalled. Manually delete
management routes added by the DHCP client.
• To reinstall management routes added by the DHCP client that is removed or replaced by the same statically
configured management routes, release the DHCP IP address and renew it on the management interface.
• Management routes added by the DHCP client have higher precedence over the same statically configured
management route. Static routes are not removed from the running configuration if a dynamically acquired
management route added by the DHCP client overwrites a static management route.
• Management routes added by the DHCP client are not added to the running configuration.
NOTE: Management routes added by the DHCP client include the specific routes to reach a DHCP server in a
different subnet and the management route.
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
The received stacking configuration is always applied on the master stack unit.
option #230 "unit-number:3#priority:2#stack-group:14"
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