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Software Configuration Guide—Release 15.0(2)SG
OL-23818-01
Chapter 45 Configuring DHCP Snooping, IP Source Guard, and IPSG for Static Hosts
Configuring DHCP Snooping
Switch# 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
Successful Transfers : 0 Failed Transfers : 21
Successful Reads : 0 Failed Reads : 0
Successful Writes : 0 Failed Writes : 21
Media Failures : 0
First successful access: Read
Last ignored bindings counters :
Binding Collisions : 0 Expired leases : 0
Invalid interfaces : 0 Unsupported vlans : 0
Parse failures : 0
Last Ignored Time : None
Total ignored bindings counters:
Binding Collisions : 0 Expired leases : 0
Invalid interfaces : 0 Unsupported vlans : 0
Parse failures : 0
Switch#
The first three lines of output show the configured URL and related timer configuration values. The next
three lines show the operating state and the amount of time left for expiry of write delay and abort timers.
Among the statistics shown in the output, startup failures indicate the number of attempts the read or
create of the file has failed upon bootup.
Note Because the location is based off in the network, you must create a temporary file on the TFTP server.
You can create a temporary file on a typical UNIX workstation by creating a 0 byte file “file” in the
directory “directory” that can be referenced by the TFTP server daemon. With some server
implementations on UNIX workstations, the file should be provided with full (777) permissions for write
access to the file.
DHCP snooping bindings are keyed on the MAC address and VLAN combination. If an entry in the
remote file has an entry for a given MAC address and VLAN set, for which the switch already has a
binding, the entry from the remote file is ignored when the file is read. This condition is referred to as
the binding collision.
An entry in a file may no longer be valid because the lease indicated by the entry may have expired by
the time it is read. The expired leases counter indicates the number of bindings ignored because of this
condition. The Invalid interfaces counter refers to the number of bindings that have been ignored when
the interface referred by the entry either does not exist on the system or is a router or DHCP snooping
trusted interface if it exists, when the read happened. Unsupported VLANs refers to the number of
entries that have been ignored because the indicated VLAN is not supported on the system. The Parse
failures counter provides the number of entries that have been ignored when the switch is unable to
interpret the meaning of the entries from the file.