11-04-2008 01:22 PM - edited 03-06-2019 02:18 AM
I am trying to enable the snooping database agent with the following command on a cisco 2960.
ip dhcp snooping database tftp://192.168.100.109/c/sw1.txt.
On the tftp server with the above address, I created the sw1.txt file in the root of the c: directory. I launched the tftp server service, but the file is not being updated. Is my format for the directory/file correct?
11-04-2008 01:38 PM
Hello Murray,
I would use:
tftp://192.168.100.109/sw1.txt
on the tftp server configure the default directory as c:\
Hope to help
Giuseppe
11-05-2008 06:53 AM
Hi, Giuseppe
Sorry, still no go. I have used two tftp servers: Tftpd32 and Quick TFTP Server Pro, setting the default path for both to c:\. I created the sw1.txt file in this path and then configured the switch with: ip dhcp snooping database tftp://192.168.100.109/sw1.txt. I can ping this workstation from the switch so I know that I have connectivity. However, the database is still not being written to the tftp server.
11-05-2008 07:21 AM
Hi, Giuseppe
I issued the following command and the output is as follows:
ncorpsw18#sh ip dhcp snoop data
Agent URL : tftp://192.168.100.109/sw1.txt
Write delay Timer : 300 seconds
Abort Timer : 300 seconds
Agent Running : No
Delay Timer Expiry : Not Running
Abort Timer Expiry : Not Running
Last Succeded Time : None
Last Failed Time : None
Last Failed Reason : No failure recorded.
Total Attempts : 0 Startup Failures : 0
Successful Transfers : 0 Failed Transfers : 0
Successful Reads : 0 Failed Reads : 0
Successful Writes : 0 Failed Writes : 0
Media Failures : 0
11-06-2008 01:20 AM
Hello Murray,
the output shows that the switch has never tried to transfer the dhcp bindings to the TFTP server:
Total Attempts : 0 Startup Failures : 0
Successful Transfers : 0 Failed Transfers : 0
assure you have a non empty dhcp snooping table
use
sh ip dhcp snooping binding
see
you can force a write with:
ip dhcp snooping database write-delay seconds
Hope to help
Giuseppe
11-06-2008 12:19 PM
There are two entries in the binding. I set the write-delay to 30 seconds and still no go. I have connectivity and I know the tftp server is working because I can redirect a sh command and create a file on the tftp server.
I wonder if there is a debug command that I could use...
03-06-2009 04:39 AM
same configuration, same effect here.
i can ping the tftp server and upload/download files, but the nice switch doesn't even try to write the snooping-database.
03-06-2009 09:44 AM
Hi, r.
I thought that I had posted a follow-up to this thread, maybe it was in another thread. What I ended up doing was removing completely dhcp snooping from the switch and then adding it back on. I believe the order is important. The last step was configuring the uplink interface to be in dhcp snooping trust.
03-06-2009 09:53 AM
Hi,r.
re-read your post. Here is a sample path.
ip dhcp snooping database tftp://10.10.100.14/sw31.txt
Now, on the tftp server, I have a folder named: c:\dhcpsnoop. Note, that my database path on the switch doesn't reference this path. That is because I use WinAgents TFTP Server. In that software, I define the root path (\) as c:\dhcpsnoop. I would think other TFTP servers would be configured the same. So, you should not have to specify the path/directory on the switch, just provide the IP address and the database name.
03-06-2009 10:00 AM
hmm, i can't find the difference makes it fail:
ASW-07#show run | inc snoo
ip dhcp snooping vlan 1,307,607,807,1107,1407,1507,1607,1807,2007,2107,2207
ip dhcp snooping database tftp://192.168.1.101/DHCP.DAT
ip dhcp snooping database write-delay 15
ip dhcp snooping
int gig 1/0/23
ip dhcp snooping limit rate 192
ip dhcp snooping trust
ASW-07#copy run tftp://192.168.1.101/test.cfg
Address or name of remote host [192.168.1.101]?
Destination filename [test.cfg]?
!!
17559 bytes copied in 2.349 secs (7475 bytes/sec)
ASW-07#copy tftp://192.168.1.101/test.cfg flash:
Destination filename [test.cfg]?
Accessing tftp://192.168.1.101/test.cfg...
Loading test.cfg from 192.168.1.101 (via Vlan1607): !
[OK - 17559 bytes]
17559 bytes copied in 0.797 secs (22031 bytes/sec)
03-06-2009 10:25 AM
Here is my complete config:
ip dhcp snooping vlan 2
no ip dhcp snooping information option
ip dhcp snooping database tftp://10.10.100.14/sw31.txt
ip dhcp snooping
Then on the uplink interface:
interface GigabitEthernet0/1
switchport mode trunk
ip dhcp snooping trust
I have dhcp snooping running at one site on over 100 switches.
So, my config is very similar to yours, except that you use a limit rate and write-delay.
You obviously can communicate with the tftp server since you can copy your flash. I just know that the dhcp is very particular about the path. I suggest experimenting with the location of "dhcp.dat" on your TFTP server. Put it in the install folder of your server, in the root directory, etc. I suggest that you make the path modifications on the TFTP server, not on the switch. Just provide the IP and name of the database file on the switch.
Here are some good commands:
sh ip dhcp snoop bind
sh ip dhcp snoop binding
sh ip dhcp snoop data
renew ip dhcp snoop data tftp://10.10.100.14/sw31.txt
sh ip dhcp snooping database
sh ip dhcp snooping database detail
clear ip dhcp snoop bind
clear ip dhcp snooping database statistics
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