37-15
Cisco 7600 Series Router Cisco IOS Software Configuration Guide, Release 12.2SX
OL-4266-08
Chapter 37 Configuring DHCP Snooping
Configuring DHCP Snooping
When configuring the DHCP snooping database agent, note the following information:
•
With releases earlier than Release 12.2(18)SXF5, the DHCP snooping database stores a maximum
of 512 bindings. If the database attempts to add more than 512 DHCP bindings, all bindings are
removed from the database.
•
With Release 12.2(18)SXF5 and later releases, the DHCP snooping database stores at least 8,000
bindings.
•
Store the file on a TFTP server to avoid consuming storage space on the router storage devices.
•
When a switchover occurs, if the file is stored in a remote location accessible through TFTP, the
newly active supervisor engine can use the binding list.
•
Network-based URLs (such as TFTP and FTP) require that you create an empty file at the configured
URL before the router can write the set of bindings for the first time.
Configuration Examples for the Database Agent
These sections provide examples for the database agent:
•
Example 1: Enabling the Database Agent, page 37-15
•
Example 2: Reading Binding Entries from a TFTP File, page 37-17
•
Example 3: Adding Information to the DHCP Snooping Database, page 37-18
Example 1: Enabling the Database Agent
The following example shows how to configure the DHCP snooping database agent to store the bindings
at a given location and to view the configuration and operating state:
Router#
configure terminal
Router(config)#
ip dhcp snooping database tftp://10.1.1.1/directory/file
Router(config)#
end
Router#
show ip dhcp snooping database detail
Agent URL : tftp://10.1.1.1/directory/file
Write delay Timer : 300 seconds
Abort Timer : 300 seconds
Agent Running : No
Delay Timer Expiry : 7 (00:00:07)
Abort Timer Expiry : Not Running
Last Succeded Time : None
Last Failed Time : 17:14:25 UTC Sat Jul 7 2001
Last Failed Reason : Unable to access URL.
Total Attempts : 21 Startup Failures : 0
Router#
renew ip dhcp snooping database
[
validation
none
] [
url
]
(Optional) Requests the read entries from a file at the given
URL.
Router#
ip dhcp snooping binding
mac_address
vlan
vlan_ID ip_address
interface
ifname
expiry
lease_in_seconds
(Optional) Adds bindings to the snooping database.
Router#
no ip dhcp snooping binding
mac_address
vlan
vlan_ID ip_address
interface
ifname
(Optional) Deletes bindings from the snooping database.
Command
Purpose
