Help with a DHCP server

[302283180]

Hi,
I cannot figure out why my DHCP server is not able to provide IPs to end-clients on a vlans controlled by a multi-layer switch. When the end clients are assigned static IPs they can talk to the DHCP server (ping or browse to the http service), but dynamic addressing does not succeed. The router has a helper redirection to the DHCP and the DHCP has a pool per vlan. What could i be missing?

Any guidance would be much appreciated. pkt attached.
Thank you, M.

[Georg Pauwen · Accepted solution]

Hello,

there are a couple of issues:

--> no DHCP pools configured on the DHCP server

--> duplicate IP addressing and redundant subinterfaces on router

--> no 'ip-helper' addresses on the Vlan interfaces of the Layer 3 switch

I attached the revised file.

[302283180]

Wow Georg, top! i get it. I had started removing the redundant subinterfaces from the router as they were actually stopping the traffic from the vlans further than the router. The very crucial bit was the helpers earlier, on the layer 3 ... makes sense, top! thank you!

[Georg Pauwen]

Hello,

the helper addresses are crucial, and easy to miss. Good luck, and happy new year !

[302283180]

Happy new year to you too!
One final question, do i really need to duplicate the DHCP pool setup on both interfaces (even if the FastEthernet one is turned off)?

[302283180]

I have answered the question by trying again without the FastEthernet dhcp pools, only the gigabit ones and it seems to work as the interface is not (yet) used. Thanks again for your great help Georg, i learned a lot today.