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Catalyst 2975 Switch Software Configuration Guide
OL-19720-02
Chapter 20 Configuring DHCP Features and IP Source Guard Features
Configuring DHCP Snooping
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:
•
Checking (validating) the relay agent information
•
Configuring the relay agent forwarding policy
Enabling DHCP Snooping and Option 82
Beginning in privileged EXEC mode, follow these steps to enable DHCP snooping on the switch:
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.
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.
Command
Purpose
Step 1
configure terminal
Enter global configuration mode.
Step 2
ip dhcp snooping
Enable DHCP snooping globally.
Step 3
ip dhcp snooping vlan
vlan-range
Enable DHCP snooping on a VLAN or range of VLANs. The range is
1 to 4094.
You can enter a single VLAN ID identified by VLAN ID number, a series
of VLAN IDs separated by commas, a range of VLAN IDs separated by
hyphens, or a range of VLAN IDs separated by entering the starting and
ending VLAN IDs separated by a space.
Step 4
ip dhcp snooping information option
Enable the switch to insert and to remove DHCP relay information
(option-82 field) in forwarded DHCP request messages to the DHCP
server. This is the default setting.
Step 5
ip dhcp snooping information option
allow-untrusted
(Optional) If the switch is an aggregation switch connected to an edge
switch, enable the switch to accept incoming DHCP snooping packets
with option-82 information from the edge switch.
The default setting is disabled.
Note
Enter this command only on aggregation switches that are
connected to trusted devices.
Step 6
interface
interface-id
Specify the interface to be configured, and enter interface configuration
mode.
Содержание 2975 - Catalyst LAN Base Switch
Страница 36: ...Contents xxxvi Catalyst 2975 Switch Software Configuration Guide OL 19720 02 ...
Страница 40: ...xxxviii Catalyst 2975 Switch Software Configuration Guide OL 19720 02 Preface ...
Страница 62: ...1 22 Catalyst 2975 Switch Software Configuration Guide OL 19720 02 Chapter 1 Overview Where to Go Next ...
Страница 398: ...13 30 Catalyst 2975 Switch Software Configuration Guide OL 19720 02 Chapter 13 Configuring VLANs Configuring VMPS ...
Страница 424: ...15 18 Catalyst 2975 Switch Software Configuration Guide OL 19720 02 Chapter 15 Configuring VTP Monitoring VTP ...
Страница 628: ...26 8 Catalyst 2975 Switch Software Configuration Guide OL 19720 02 Chapter 26 Configuring UDLD Displaying UDLD Status ...
Страница 660: ...28 8 Catalyst 2975 Switch Software Configuration Guide OL 19720 02 Chapter 28 Configuring RMON Displaying RMON Status ...
Страница 888: ...38 32 Catalyst 2975 Switch Software Configuration Guide OL 19720 02 Chapter 38 Troubleshooting Troubleshooting Tables ...