OSPF On A DHCP Client Interface
Here are two scenarios:
- You want to have all your spare CPE routers configured with a standard config, so a field tech can just pick one up and plug it in without configuring it.
- You are running two or more local loops to a CPE router, and you don't want the installer to have to figure out which local loop goes into which port on the router.
What to do? Set the CPE router up as a DHCP client with OSPF running on all interfaces! This way, when it gets plugged in to one or more local loops, it will get its IP from the network and will automatically bring up an OSPF adjacency on each link.
On the upstream router, you will need to configure one or more subintercaces, and a DHCP pool for each interface. Then you can either add a corresponding OSPF network statement for each, or just put in a generic one to cover them all.
ip dhcp pool CUSTOMER_A-LINK_1 network 172.16.2.0 255.255.255.248 ip dhcp pool CUSTOMER_A-LINK_2 network 172.16.2.8 255.255.255.248 interface GigabitEthernet0/1.100 ip address 172.16.2.1 255.255.255.248 interface GigabitEthernet0/1.101 ip address 172.16.2.9 255.255.255.248 router ospf 1 network 172.16.2.0 0.0.0.255 area 0
On the CPE router, you just need to be sure that the WAN ports are set for DHCP, and a network statement covers them.
interface FastEthernet0 ip address dhcp interface FastEthernet1 ip address dhcp router ospf 1 network 0.0.0.0 255.255.255.255 area 0