Cisco 7604 User Manual

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Cisco 7600 Series Router Cisco IOS Software Configuration Guide, Release 12.2SX
OL-4266-08
Chapter 37 Configuring DHCP Snooping
Configuring DHCP Snooping
Configuring DHCP Snooping Rate Limiting on Layer 2 LAN Interfaces
To configure DHCP snooping rate limiting on a Layer 2 LAN interface, perform this task:
When configuring DHCP snooping rate limiting on a Layer 2 LAN interface, note the following
information:
• We recommend an untrusted rate limit of not more than 100 packets per second (pps).
• If you configure rate limiting for trusted interfaces, you might need to increase the rate limit on trunk
ports carrying more than one VLAN on which DHCP snooping is enabled.
• DHCP snooping puts ports where the rate limit is exceeded into the error-disabled state.
This example shows how to configure DHCP packet rate limiting to 100 pps on Fast Ethernet port 5/12:
Router# configure terminal
Router(config)# interface FastEthernet 5/12
Router(config-if)# ip dhcp snooping limit rate 100
Router(config-if)# do show ip dhcp snooping | begin pps
Interface Trusted Rate limit (pps)
------------------------ ------- ----------------
FastEthernet5/12 no 100
Router#
Configuring the DHCP Snooping Database Agent
To configure the DHCP snooping database agent, perform one or more of the following tasks:
Command Purpose
Step 1
Router(config)# interface { type
1
slot/port |
port-channel
number }
1. type = ethernet, fastethernet, gigabitethernet, or tengigabitethernet
Selects the interface to configure.
Note Select only LAN ports configured with the
switchport command or Layer 2 port-channel
interfaces.
Step 2
Router(config-if)# ip dhcp snooping limit rate
rate
Configures DHCP packet rate limiting.
Step 3
Router(config-if)# no ip dhcp snooping limit rate
Disables DHCP packet rate limiting.
Step 4
Router(config-if)# do show ip dhcp snooping |
begin pps
Verifies the configuration.
Command Purpose
Router(config)# ip dhcp snooping database { _url |
write-delay
seconds | timeout seconds }
(Required) Configures a URL for the database agent (or file)
and the related timeout values.
Router(config)# no ip dhcp snooping database
[write-delay | timeout]
Clears the configuration.
Router# show ip dhcp snooping database [detail]
(Optional) Displays the current operating state of the
database agent and statistics associated with the transfers.
Router# clear ip dhcp snooping database statistics
(Optional) Clears the statistics associated with the database
agent.

Cisco 7604 Specifications

General

Brand	Cisco
Model	7604
Category	Network Router
Language	English