Vlan DHCP not working

[ColinP]

Hi i cant get devices on the wireless vlans for teachers and students working - they are not getting DHCP - if i put manual ip address's in they work ok

 

below is my wireshark print out with details of devices

 

17.16.80.210 is the teachers vlan on on HP flex 5700

 

192.168.27.106 is my dhcp server

 

in wire shark i can see that the dhcp relay is working as it gets to the dhcp server and the dhcp server offers back an ip address, but my devices dont recive any address..

 

this has got me stumped

[RobD]

Have you added a IP helper address on the switch?

[Davit2005]

Could you give a small description of your setup, remove any sensitive information.

 

List the traffic path between Device and DHCP server, any firewall and any routing devices between them?

 

What switches and any running config.

[QwertyMash]

Hello,

 

Just to get to basics.

 

Have you give the VLAN Interfaces an IP address?

Have you set IP helper address on the VLANs and pointed it to your DHCP server.

Have you created the pools in DHCP using the correct range and subnets etc?

 

But yeah if you can send us the basics of your config I am sure someone here will crack it

[ColinP]

Switch is a hp flexfabric 5700

we have 4 vlans, with the switch having an interface in each vlan

 

its hp so it is dhcp relay rather than ip helper and it is configured -- i can see dhcp requests from the vlans on the dhcp server coming from the switch ip in each vlan

 

i have the dhcp scopes setup on the server and the server is sending a corresponding ipaddress back to the switch depending on which vlan requested it.

 

I have had this working on my old server 2008 and old core switch, and as far as i can see everything is setup the same

 

setup is

Default Vlan
191.168.24.0	191.168.31.255	191.168.24.1	191.168.31.254	255.255.248.0	21	1	192.168.30.15	Main School Subnet
172.16.80.0	172.16.80.255	172.16.80.1	172.16.80.254	255.255.255.0	24	80	172.16.80.15	Teachers Wi-Fi Subnet
172.16.99.0	172.16.99.255	172.16.99.1	172.16.99.254	255.255.255.0	24	99	172.16.99.15	Guest Wi-Fi Subnet
192.168.16.0	192.168.23.255	192.168.16.1	192.168.23.254	255.255.248.0	21	100	192.168.23.15	iPad & Apple Airplay Subnet

DHCP server is on 192.168.27.106

 

Switch has the following ipaddress's

Default Vlan 192.168.31.210

Vlan80 172.16.80.210

Vlan99 172.16.99.210

vlan100 192.168.23.210

 

On the screenshot above you can see that dhcp relay is forwading to the dhcp and the server resonds with a correct ip address

[ColinP]

for anyone else who might read this i had to add static routes on the DHCP sever and everything works fine.

 

Route add 172.16.80.0 mask 255.255.255.0 192.168.31.210 -p

Route add 172.16.80.0 mask 255.255.255.0 192.168.31.210 -p

Route add 172.16.99.0 mask 255.255.255.0 192.168.31.210 -p

Route add 192.168.42.0 mask 255.255.255.0 192.168.31.210 -p

Route add 192.168.16.0 mask 255.255.248.0 192.168.31.210 -p

[Davit2005]

Strange why you had to do that. If the DHCP servers gateway is on the same switch then it should of worked.

 

Only once have I ever had to add routes and that was on a HP MSM for Webmail etc access to our internal network via the firewall.