Enabling Dhcp Snooping Globally; Configuring Dhcp Snooping - Cisco WS-SUP32-GE-3B - Supervisor Engine 32 Software Configuration Manual

Chapter 34

Configuring DHCP Snooping

Configuring DHCP Snooping
These sections describe how to configure DHCP snooping:
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Enabling DHCP Snooping Globally

Enable this feature during a maintenance window, because after you enable DHCP snooping globally,
Note
the switch drops DHCP requests until you configure the ports.
To enable DHCP snooping globally, perform this task:
Command
Step 1
Router(config)# ip dhcp snooping
Router(config)# no ip dhcp snooping
Step 2
Router(config)# do show ip dhcp snooping |
include Switch
This example shows how to enable DHCP snooping globally:
Router# configure terminal
Enter configuration commands, one per line.
Router(config)# ip dhcp snooping
Router(config)# do show ip dhcp snooping | include Switch
Switch DHCP snooping is enabled
Router(config)#
When DHCP snooping is disabled and DAI is enabled, the switch shuts down all the hosts because all
Note
ARP entries in the ARP table will be checked against a nonexistent DHCP database. When DHCP
snooping is disabled or in non-DHCP environments, use ARP ACLs to permit or to deny ARP packets.
OL-11439-03
Enabling DHCP Snooping Globally, page 34-7
Enabling DHCP Option-82 Data Insertion, page 34-8
Enabling the DHCP Option 82 on Untrusted Port Feature, page 34-8
Enabling DHCP Snooping MAC Address Verification, page 34-9
Enabling DHCP Snooping on VLANs, page 34-9
Configuring the DHCP Trust State on Layer 2 LAN Interfaces, page 34-11
Configuring DHCP Snooping Rate Limiting on Layer 2 LAN Interfaces, page 34-12
Configuring the DHCP Snooping Database Agent, page 34-12
Configuration Examples for the Database Agent, page 34-13
Displaying a Binding Table, page 34-16
Catalyst Supervisor Engine 32 PISA Cisco IOS Software Configuration Guide, Release 12.2ZY
Purpose
Enables DHCP snooping globally.
Disables DHCP snooping.
Verifies the configuration.
End with CNTL/Z.
Configuring DHCP Snooping
34-7