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Hi all,

I'm trying to setup a VLAN environment in my production and for now I setup a testing lab. Below the H/W details

1 HP Switch 5412zl with firmware  K.13.09 -
1 HP Switch 2824 with firmware I.10.43 -
1 Domain controller with DHCP and DNS W2K3 R2 SP2 -
1 client on DHCP with XP SP2 - DHCP
1 client with static IP for Procurve PCM B.02.322 with IDM A.02.25 -

The VLAN info is as follows:

manually set up on both switches

VLAN1 - on 5412zl -
VLAN1 - on 2824 -
VLAN100 - the procurve static IP client -
VLAN200 - the domain controller -
VLAN150 - the DHCP client -

All looks good except the client doesn't get a DHCP address. If I move the client on a static IP say, then everyone sees everyone in any VLAN. Which for now I want this to happen.

Once I put the client on VLAN150 on DHCP, the request gets to VLAN200 DHCP server (I put an IP helper-address in VLAN150 to point to the domain controller/DHCP/DNS on VLAN200 So the DHCP address appears as leased in the DHCP server - see the DHCPLeaseserver.bmp for details

In the client system log I can see an error (is logged every second in the system log) - see the dhcpclienterror.bmp -  I can see a NACK message. I understand what NACK means. If I press F5 to refresh, I can see that the address lease expiration increases every second, so I assume that there is a loop (sort of) The client asks for a DHCP address, the server gets the request, releases an IP, the client doen't get the IP, so the client asks again, the server gets the request, and releases a new address (which it happenes to be the same IP, but the expiration time reflects the new lease), and so on.

in the DHCP log in the server I can see some activity logged every second, see DHCPLogSample.txt

I also attached the sh conf on both switches.

In my current setup the domain controller is on port 8 on the 2848 switch.
on 2848 the uplink to 5412zl is on port 20
5412zl uplink is on port B24
the Procurve machine is on port B12
the DHCP client is on port B4.

Let me know if you need more info.

What's missing in my setup so the client can get a DHCP address?

Thank you very much for your help!
Avatar of ck459
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Your ip addresses on the VLANs are the same on both switches. I think your DHCP request is taking the 5412 for example to reach the DHCP server, while the DHCP server is taking the path back via the 2824.... (as both these switches are configured for intervlan routing.)
For normal ip routing this could work, but an for an IP helper it is critical that the reply from the DHCP request arrives on the same switch where the request from the client was received.
Try doing the intervlan routing only on one switch, and it should work.  (just remove the vlan ip addresses from the 2824 switch)
if you want redundant setup with ip addresses on both the 5412 and 2824, you need to look at VRRP. with VRRP you will have a physical ip address on each VLAN interface which is different, and a VRRP virtual IP address that is the same on each switch. You might need a special license on the HP procurves to run VRRP.
Avatar of sblanken


Hi Kurt, thank you for your comment. Unfortunately, after I disabled the IPs for the VLAN 100/150/200 on the 2824 switch, I was still not able to get a DHCP address. There was no DHCP traffic anymore, the server didnt get any request. If I put the client on static IP in 192.168.150.x range (the DHCP VLAN range) then everyone sees everyone, once I turned the IP back on DHCP, the client request didnt reach the DHCP server anymore and the client didnt get an IP.

Anyways, I decided to simplify my lab. Now I have only 1 switch 5412zl, 1 server VLAN and 1 client VLAN

VLAN1  default settings  I erased my startup config and started from scratch
VLAN200  server
VLAN 150  client

My server is on port B2 and IP is
My client is on port B3 and when I assigned static IP everything was fine, DNS was OK, WINS was OK, it was able to find the server by IP and by name.
When I moved the client back on DHCP, the client and the server started the same thing as before, the client DHCP request reaches the server, the server assigns an IP but the client never gets it back, except the NACK.
There is an IP Helper address on VLAN150 that points to the DHCP server on VLAN 200

I really dont know what Im doing wrong. Any suggestions are appreciated!

PS: I attached the current 5412zl config as of 07/18/08

Strange, Your config looks ok to me. Looks like a host or DHCP server issue.
Could you check the following :
From the windows 2003 server, go to DHCP, under administrative tools.

Under the DHCP tree, expand domain (, and select Address leases. Look there for the MAC address of the network card that is having difficulties obtaining IP automatically. You may find that this entry will contain BAD ADDRESS or something similar under Lease Expiration column. Delete this entry.

Go back to the PC at fault and run ipconfig /release, followed by ipconfig /nenew, under in the DOS console.

make sure no other DHCP server is active (shouldn't be the case, but you never know). Even a DHCP server on the 5412 switch. If the DHCP service on that switch is active, try shutting it down.
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