Cisco Systems 3560 사용자 설명서
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Catalyst 3560 Switch Software Configuration Guide
OL-8553-06
Chapter 21 Configuring DHCP Features and IP Source Guard
Configuring DHCP Snooping
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You can display DHCP snooping statistics by entering the show ip dhcp snooping statistics user
EXEC command, and you can clear the snooping statistics counters by entering the clear ip dhcp
snooping statistics privileged EXEC command.
EXEC command, and you can clear the snooping statistics counters by entering the clear ip dhcp
snooping statistics privileged EXEC command.
Note
Do not enable Dynamic Host Configuration Protocol (DHCP) snooping on RSPAN VLANs. If
DHCP snooping is enabled on RSPAN VLANs, DHCP packets might not reach the RSPAN
destination port.
DHCP snooping is enabled on RSPAN VLANs, DHCP packets might not reach the RSPAN
destination port.
Configuring the DHCP Server
The switch can act as a DHCP server. By default, the Cisco IOS DHCP server and relay agent features
are enabled on your switch but are not configured. These features are not operational.
are enabled on your switch but are not configured. These features are not operational.
For procedures to configure the switch as a DHCP server, see the “Configuring DHCP” section of the
“IP addressing and Services” section of the Cisco IOS IP Configuration Guide, Release 12.2 from the
Cisco.com page under Documentation > Cisco IOS Software > 12.2 Mainline > Configuration
Guides.
“IP addressing and Services” section of the Cisco IOS IP Configuration Guide, Release 12.2 from the
Cisco.com page under Documentation > Cisco IOS Software > 12.2 Mainline > Configuration
Guides.
Configuring the DHCP Relay Agent
Beginning in privileged EXEC mode, follow these steps to enable the DHCP relay agent on the switch:
To disable the DHCP server and relay agent, use the no service dhcp global configuration command.
See the “Configuring DHCP” section of the “IP Addressing and Services” section of the Cisco IOS IP
Configuration Guide, Release 12.2 from the Cisco.com page under Documentation > Cisco IOS
Software > 12.2 Mainline > Configuration Guides for these procedures:
Configuration Guide, Release 12.2 from the Cisco.com page under Documentation > Cisco IOS
Software > 12.2 Mainline > Configuration Guides for these procedures:
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Checking (validating) the relay agent information
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Configuring the relay agent forwarding policy
Specifying the Packet Forwarding Address
If the DHCP server and the DHCP clients are on different networks or subnets, you must configure the
switch with the ip helper-address address interface configuration command. The general rule is to
configure the command on the Layer 3 interface closest to the client. The address used in the ip
switch with the ip helper-address address interface configuration command. The general rule is to
configure the command on the Layer 3 interface closest to the client. The address used in the ip
Command
Purpose
Step 1
configure terminal
Enter global configuration mode.
Step 2
service dhcp
Enable the DHCP server and relay agent on your switch. By default, this
feature is enabled.
feature is enabled.
Step 3
end
Return to privileged EXEC mode.
Step 4
show running-config
Verify your entries.
Step 5
copy running-config startup-config
(Optional) Save your entries in the configuration file.