Troubleshooting Tips - Cisco Catalyst 4500 Series Software Configuration Manual

Chapter 59 Configuring the Cisco IOS DHCP Server
Command or Action
Step 16
Switch(dhcp-config)# network
network-number [mask | /prefix-length]
[secondary]
Step 17
Switch(config-dhcp-subnet-secondary)#
override default-router address [address2
... address8]
Step 18
Switch(config-dhcp-subnet-secondary)#
override utilization high
percentage-number
Step 19
Switch(config-dhcp-subnet-secondary)#
override utilization low
percentage-number
Step 20
Switch(config-dhcp-subnet-secondary)# end

Troubleshooting Tips

If you are using secondary IP addresses under a single loopback interface and using secondary subnets
under a DHCP pool, use one DHCP pool to configure networks for all the secondary subnets instead of
using one pool per secondary subnet. The network network-number [mask | /prefix-length] [secondary]
command must be configured under a single DHCP address pool rather than multiple DHCP address
pools.
The following is the correct configuration:
ip dhcp pool dhcp_1
network 172.16.1.0 255.255.255.0
network 172.16.2.0 255.255.255.0 secondary
network 172.16.3.0 255.255.255.0 secondary
network 172.16.4.0 255.255.255.0 secondary
!
interface Loopback111
ip address 172.16.1.1 255.255.255.255 secondary
Catalyst 4500 Series Switch, Cisco IOS Software Configuration Guide - Cisco IOS XE 3.9.xE and IOS 15.2(5)Ex
Purpose
(Optional) Specifies the network number and mask of a secondary
DHCP server address pool.
• Any number of secondary subnets can be added to a DHCP
server address pool.
During execution of this command, the configuration mode
•
changes to DHCP pool secondary subnet configuration mode,
which is identified by (config-dhcp-subnet-secondary)#
prompt. In this mode, the administrator can configure a
default device list that is specific to the subnet.
See Troubleshooting Tips section if you are using secondary
•
IP addresses under a loopback interface with DHCP
secondary subnets.
(Optional) Specifies the default device list that is used when an IP
address is assigned to a DHCP client from a particular secondary
subnet.
If the subnet-specific override value is configured, this
•
override value is used when assigning an IP address from the
subnet; the network-wide default device list is used only to
set the gateway device for the primary subnet.
If this subnet-specific override value is not configured, the
•
network-wide default device list is used when assigning an IP
address from the subnet.
(Optional) Sets the high utilization mark of the subnet size.
This command overrides the global default setting specified
•
by the utilization mark high command.
(Optional) Sets the low utilization mark of the subnet size.
This command overrides the global default setting specified
•
by the utilization mark low command.
Exits DHCP secondary subnet configuration mode and returns to
privileged EXEC mode.
Configuring DHCP Address Pools
59-15