Cisco – DHCP assign IP address based on MAC address with Cisco CE 500 platform

what I mainly want to know from someone who has already gone through all this is: Is a "MAC authentication" that still generates EAP packets a valid approach?

Here's a freeradius-users thread which answers most of these questions.

The crux is:

• Using EAP for MAC auth makes no real sense.
• But it isn't bad either if it's at least correctly implemented.
• Users on the freeradius list didn't think Cisco's SG series implements 802.1x EAP MAB correctly, since the EAP Service-Type is missing. As Nick Lowe mentioned, if the EAP Service-Type is missing, it becomes awkward, hackish and potentially unreliable to discriminate between the type of service being used by a client.

is it possible to assign a preconfigured IP address based on a port a device is connected to? What devices do I need for this?

You can use a Cisco switch and an IOS that supports DHCP Server Port-Based Address Allocation on your switch; you also must issue DHCP from your switch. Assume that you have got Fa0/1 and Fa0/2 in Vlan120.

ip dhcp use subscriber-id client-id
ip dhcp subscriber-id interface-name
ip dhcp excluded-address 192.0.2.1 192.0.2.10
!
ip dhcp pool VLAN120
   network 192.0.2.0 255.255.255.0
   default-router 192.0.2.1
   dns-server 192.0.2.5
   reserved-only
   address 192.0.2.101 client-id "Fa0/1" ascii
   address 192.0.2.102 client-id "Fa0/2" ascii

This configuration reserves addresses for fa0/1 and fa0/2. The same address will always be assigned to those ports.