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HP Procurve - VLANs and DHCP Helper Address

I've predominately used Cisco and Enterasys, and for the life of me I cannot get this to work properly on an HP Pro Curve 2910al switch.  The scope here:  I've got a Windows 2003 DHCP server.  IP address is  This server has two DHCP scopes - (VLAN 10) and (VLAN 100).  

On the switch level, I have all ports set to use VLAN 10 untagged and VLAN 100 as tagged.  I've setup both VLANs with ip-helper address of  

This is the setup for us to be able to daisy chain a PC behind a Phone, and have the two on separate networks (VLAN 10= data, VLAN100=Voice).  Using a custom DHCP option, I can force the phone to turn on Layer 2 tagging and assign itself to VLAN 100.  

So, when I attach the phone, it hits DHCP and takes an IP in the data range.  It then see's it needs to change it's VLAN and goes through a network re-configure.  It reboots and attempts DHCP (trying to get an address in VLAN 100).  The phone never get's an IP.

Note: There is a default VLAN that I was using to stack the switches.  I've cut back to using a single switch and changed the primary VLAN to VLAN10, which has done nothing.

What is the proper (port) setup to allow DHCP for both subnets?
Avatar of lruiz52
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Please post your config! But it should look something like this;

vlan 10
name "VLAN10"
untagged 1-39,41-42,44
ip address
tagged 47-48
vlan 100
name "VLAN100"
untagged 40,43,45-46
qos priority 7
ip helper-address
ip address
tagged 1-39,41-42,44,47-48
Avatar of JamesonJendreas


My config is as follows:

Vlan 1
no ip address
no untagged 1-48

Vlan 10
Name "Data"
Untagged 1-48
ip address
ip helper-address

Vlan 100
Name "Voice"
Tagged 1-48
ip address
ip hekper-address

primary-vlan 10

So each port is set the same - Untagged for data, Tagged for voice.  This includes the port to which the DHCP server is attached.  My thought is the tagging on that port, but I've tried every combo
Please disregard the typo - I'm not copy/pasting as the laptop I currently have setup to the switch is not on my LAN (I'm setting up a bench network)
remove the IP helper-address from VLAN 10

ensure that the DHCP server either has the 2910 as its default gateway, or has a static route to the network pointing at the 2910
since the dhcp server is on vlan 10, you  dont need the ip helper-address, so you can remove it.  Also add the voice command to vlan 100 and set qos priority 7
Confirmed that the DHCP server can get to the the VLAN 100 (can ping a static device on the network, as well as the 2960 is the gateway).  I removed the IP helper from VLAN 10, but still cannot get an IP in the VLAN 100.  

Phone contacts DHCP, get's it's VLAN info, reboots, then hangs on DHCP
Re: Voice command and QoS - I haven't applied the voice to the VLAN yet, I was working out the DHCP issues first.  I actually have some 40+ switches to setup, so I'm trying to get one up and running properly so that I can just paste into the remaining switches

Thanks for the heads up as well.
dumb questions

have you created a superscope, or a scope just for the .100 subnet ?
can you confirm that there is a line in the config that says "IP routing" ?
Make sure you have correctly configured your DHCP server, especially Default Gateway option for Voice vlan (it should be
I can confirm that IP routing is enabled, and DHCP seems to be configured properly
can you post a full copy of the config
OK - The issue looks like it might be an issue with the DHCP server itself.  I did two things:
1. Run a wireshark on the DHCP server during DHCP request.  I see the phone request DHCP twice.  The second request is coming from the switch in the .100.0 network.
2. If i deactivate the .10.x scope, I do get an IP in the 100.x subnet.
the request from the switch is correct.

Presuming that you DHCP server is on Windows, can you please run the following and post the output

netsh dhcp server dump > dhcp-dump.txt

Open in new window

Great - I'll dump the DHCP info when I get back into the lab.  

Mainly I am concerned about the switch setup, not the DHCP server.  This is a test/lab setup prior to pushing the switches out to sites.  I'm mostly testing proper VLAN and routing setups.  The production environment will be slightly different than what's in the lab - DHCP will be handled by a Cisco router.  My lab setup IS using a Windows 2k3 server for DHCP (I don't have a spare Cisco router handy)
Avatar of ArneLovius
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You got it - Each site (3 total) only have Cisco routers and the HP switches I am rolling out.  DHCP is done at each site by the routers.