60-7
Catalyst 4500 Series Switch, Cisco IOS Software Configuration Guide - Cisco IOS XE 3.9.xE and IOS 15.2(5)Ex
Chapter 60 Configuring DHCP Snooping, IP Source Guard, and IPSG for Static Hosts
Configuring DHCP Snooping
•
Configuring DHCP Snooping with an Ethernet Channel Group, page 60-12
•
Enabling the DHCP Snooping Database Agent, page 60-13
•
Limiting the Rate of Incoming DHCP Packets, page 60-13
•
Configuration Examples for the Database Agent, page 60-15
Note
For DHCP server configuration information, refer to “Configuring DHCP” in the
Cisco IOS IP and IP
Routing Configuration Guide
at:
http://www.cisco.com/en/US/docs/ios/12_2/ip/configuration/guide/1cfdhcp.html
Default Configuration for DHCP Snooping
DHCP snooping is disabled by default.
shows all the default configuration values for each
DHCP snooping option.
If you want to change the default configuration values, see the
section.
Enabling DHCP Snooping
Note
When DHCP snooping is enabled globally, DHCP requests are dropped until the ports are configured.
Consequently, you should probably configure this feature during a maintenance window and not during
production.
To enable DHCP snooping, perform this task:
Table 60-1
Default Configuration Values for DHCP Snooping
Option
Default Value/State
DHCP snooping
Disabled
DHCP snooping information option
Enabled
DHCP snooping information option
allow-untrusted
Disabled
DHCP snooping limit rate
Infinite (functions as if rate limiting were disabled)
DHCP snooping trust
Untrusted
DHCP snooping vlan
Disabled
Command
Purpose
Step 1
Switch(config)#
ip dhcp snooping
Enables DHCP snooping globally.
You can use the
no
keyword to disable DHCP snooping.
Step 2
Switch(config)#
ip dhcp snooping
vlan
number
[
number
] |
vlan
{
vlan range
}]
Enables DHCP snooping on your VLAN or VLAN
range.
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