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DHCP over Vlans working on cisco not on HP 2650

Ryan1979
Advisor

DHCP over Vlans working on cisco not on HP 2650

We have a cisco 3750 stack with about 10 vlans on it acting a ‘router’ to route vlans to a single DHCP server with a scope for every vlan.

This works great for the cisco 2950 edge network switches (which we were using previously) and is really easy to setup however for the procurve 2650’s all I seem to be able to do is get a DHCP from the management scope, not the vlans scopes. I have setup 2 vlans (the default –vlan1) and also vlan 18. Vlan 18 is assigned ports 1-48 and they are untagged. Ports 49 and 50 are the fibre ports (only 49 is currently connected) and are on vlan 1 and vlan 18 with tagging on both. I have also on the HP 2650 setup a ip helper address (which I didn’t think I needed to do on the edge switches). Any thoughts or ideas would be greatly appreciated.

15 REPLIES
Mohieddin Kharnoub
Honored Contributor

Re: DHCP over Vlans working on cisco not on HP 2650

Hi

Usually in multiple vlans environment, you need to add a ip helper-address, and one more thing, you need to be sure that in your DHCP scope for Vlan18, that the router parameter should be the Vlan18 ip address on the routing switch.

Also, i prefer you untagg port 49-50 for Vlan1 and keep it tagged for Vlan18.

If you connect a pc to any port 1-48 that is untagged to Vlan18, and assign a static ip address, try to ping your DHCP server, and your gateway (vlan18 ip address on the routing switch).

If that didn't help, attach the config of this switch configuration here, so we can worked out together.

Good Luck !!!
Science for Everyone
Ryan1979
Advisor

Re: DHCP over Vlans working on cisco not on HP 2650

Thanks for your help Mohieddin

I already have a ip helper-address assigned and I have also previously added the router for the switch in the DHCP advanced options. If I use a cisco switch (like a 2950) I dont have a problem, only with the HP.

Dumb question,. How do i export the switch config for you?

Thanks in advance
Ryan1979
Advisor

Re: DHCP over Vlans working on cisco not on HP 2650

here is the startup config, I hope thats all u need thought its very small.

Thanks in advance
Ryan1979
Advisor

Re: DHCP over Vlans working on cisco not on HP 2650

This is also the 3750 cisco switch config to show the vlans etc.

Ryan1979
Advisor

Re: DHCP over Vlans working on cisco not on HP 2650

Oh and lastly, Static IP on the 18 subnet I still can not ping the gateway or the DHCP server.
psycho.chicken
Regular Advisor

Re: DHCP over Vlans working on cisco not on HP 2650

is your dhcp server on this switch, or out one of teh 49 or 50 ports on another switch?
psycho.chicken
Regular Advisor

Re: DHCP over Vlans working on cisco not on HP 2650

what is teh dhcp servers default gateway? it should be the vlan ip of the vlan it belongs to...
Ryan1979
Advisor

Re: DHCP over Vlans working on cisco not on HP 2650

the default gateway is a windows 2003 server on 10.12.7.252. It is hanging off the core switch.

Port 49/50 are fibre links to the core gig switch.
psycho.chicken
Regular Advisor

Re: DHCP over Vlans working on cisco not on HP 2650

the dhcp server's default gateway should be it's vlan's IP

example

my vlans are
10.3.10.1 /24
10.3.10.1 /24

so any client that gets a 10.3.10.x also gets 10.3.10.1 as it's default gateway

on the switch that has ip routign enabled it's default gateway should be your router

i thin what's happening is the ping request is makign it to the dhcp server, but not back...

try correcting the default gateway's
psycho.chicken
Regular Advisor

Re: DHCP over Vlans working on cisco not on HP 2650

the core should be the ONLY thing with the gateway of last resort, an external router...

all the other switches should have their default gateway's pointign to the core

All clients should point to their vlan's ip...
psycho.chicken
Regular Advisor

Re: DHCP over Vlans working on cisco not on HP 2650

make sure you have the ports TAGGED on both sides for all vlans on any uplinks

make sure the ports with pc's and/or servers are UNTAGGED with the correct vlan you want them in...

i have forgotten to TAG a uplink with one vlan id and it really goofs troubleshooting up...
Ryan1979
Advisor

Re: DHCP over Vlans working on cisco not on HP 2650

I wrote it wrong.

The DHCP ip address is 10.12.7.252, the default gateway for the network is 10.12.7.253, and the default gateway for each vlan is 10.12.vlanid.254. The DHCP server router address is 10.12.vlanid.254.

It is not getting to the DHCP server becuase if it was I would be able to set a static IP and ping it, and I can not do this.

psycho.chicken
Regular Advisor

Re: DHCP over Vlans working on cisco not on HP 2650

can you post both your configs...

copy paste...
psycho.chicken
Regular Advisor

Re: DHCP over Vlans working on cisco not on HP 2650

lol i wrote my vlans wrong too...
10.3.10.1 /24 vlan10
10.3.20.1 /24 vlan20
10.3.30.1 /24 vlan30
10.3.0.200 /24 vlan90 (servers)
etc...


vlan 10 ip helper-address 10.3.0.70 (in vlan 90)
vlan 20 ip helper-address 10.3.0.70
dhcp-relay

can you ping anything else?
Ryan1979
Advisor

Re: DHCP over Vlans working on cisco not on HP 2650

solved