DHCP relay

[JVANH]

This may be a dumb question, but I'm gonna ask anyway.
If I setup a single DHCP server with a scope that encompasses a subnet like 10.0.0.0/16 and I segment my network using VLANs to something like 10.0.1.0/24, 10.0.2.0/24, etc. And if I use DHCP Relay to broadcast DHCP packets to all VLANS.

What prevents me from having a device assigned an IP address that is out of it’s VLANs subnet. Like on VLAN 10.0.2.0/24 a device gets IP 10.0.3.25? Or do I need to setup multiple DHCP servers one for each VLAN?

 

[biv343]

You would need to have multiple scopes for each subnet. When the packet is relayed to the DHCP server (or subnet that the DHCP server resides on), the server will receive a source address identifying which subnet the request is for. The DHCP server will then look for an available scope that meets those criteria.

You'll need a scope for 10.0.2.0/24, 10.0.3.0/24, etc.

 

[goodingsd]

If your DHCP server has a /16 scope and different VLAN's - /24 subnets - are forwarding to DHCP server it won't work. Why ? Because the forwarded DHCP broadcast includes the source VLAN information that ID's which scope to hand out addresses from. This source information is the forwarding VLAN's default gateway.

 

[xyCruiseryx]

a subnet like 10.0.0.0/16 and I segment my network using VLANs to something like 10.0.1.0/24, 10.0.2.0/24, etc.

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You´ve got a IP-Subnet Error the network: 10.0.0.0/16 get a range from 10.0.0.1 till 10.0.255.254. Your other Vlans are in the range...or did´nt i understand what you meaning ??