Cisco Catalyst 3750-E - Enabling Dhcp Snooping on Private Vlans; Enabling the Cisco Ios Dhcp Server Database; Enabling the Dhcp Snooping Binding Database Agent

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Catalyst 3750-E and 3560-E Switch Software Configuration Guide
OL-9775-08
Chapter 22 Configuring DHCP Features and IP Source Guard
Configuring DHCP Features
Enabling DHCP Snooping on Private VLANs
You can enable DHCP snooping on private VLANs. If DHCP snooping is enabled, the configuration is
propagated to both a primary VLAN and its associated secondary VLANs. If DHCP snooping is enabled
on the primary VLAN, it is also configured on the secondary VLANs.
If DHCP snooping is already configured on the primary VLAN and you configure DHCP snooping with
di
fferent settings on a secondary VLAN, the configuration for the secondary VLAN does not take effect.
You must configure DHCP snooping on the primary VLAN. If DHCP snooping is not configured on the
primary VLAN, this message appears when you are configuring DHCP snooping on the secondary
VLAN, such as VLAN 200:
2w5d:%DHCP_SNOOPING-4-DHCP_SNOOPING_PVLAN_WARNING:DHCP Snooping configuration may not take
effect on secondary vlan 200. DHCP Snooping configuration on secondary vlan is derived
from its primary vlan.
The show ip dhcp snooping privileged EXEC command output shows all VLANs, including primary
and secondary private VLANs, on which DHCP snooping is enabled.
Enabling the Cisco IOS DHCP Server Database
For procedures to enable and configure the Cisco IOS DHCP server database, see the “DHCP
Configuration Task List” section in the “Configuring DHCP” chapter of the Cisco IOS IP Configuration
Guide, Release 12.2.
Enabling the DHCP Snooping Binding Database Agent
Beginning in privileged EXEC mode, follow these steps to enable and configure the DHCP snooping
binding database agent on the switch:
Command Purpose
Step 1
configure terminal Enter global configuration mode.
Step 2
ip dhcp snooping database
{flash[number]:/filename |
ftp://user:password@host/filename |
http://[[username:password]@]{hostna
me | host-ip}[/directory]
/ima
ge-name.tar |
rcp://user@host/filename}|
tftp://host/filename
Specify the URL for the database agent or the binding file by using one
of t
hese forms:
• flash[number]:/filename
(Optional) Use the nu
mber parameter to specify the stack member
number of the stack master. The range for number is 1 to 9.
• ftp://user:password@host/filename
• http://[[username:password]@]{hostname | host-ip}[/directory]
/ima
ge-name.tar
• rcp://user@host/filename
• tftp://host/filename
Step 3
ip dhcp snooping database timeout
seconds
Specify (in seconds) how long to wait for the database transfer process to
finish before stopping the process.
The default is 300 seconds. The range is 0 to 86400. Use 0 to define an
i
nfinite duration, which means to continue trying the transfer indefinitely.