If you have a Cisco ASR or smaller service router, you probably noticed that the device have a dedicated management interface.
This special interface is a mapped to a Vritual Routing and Forwarding (VRF) instance. VRF allow multiple routing tables to coexist within the same router.
You will first ensure that you have the VRF instance declared in the configuration :
vrf definition Mgmt-intf
Then you must set the VRF on the physical interface :
vrf forwarding Mgmt-intf
And configure the IP address as you usually do on the physical interface :
ip address <ip_addr> <netmask>
See the full configuration below (example) :
interface GigabitEthernet0 vrf forwarding Mgmt-intf ip address 192.168.0.1 255.255.255.0 negotiation auto
You probably want to set a gateway for this VRF interface if your OOB access is directly through the Internet as followed :
ip route vrf Mgmt-intf 0.0.0.0 0.0.0.0 <gw_ip_addr>
If you want to troubleshoot, you will notice that the traditional ping command won’t work since this interface is a virtual layer on top of the physical interface. You will have to adjust your command as followed to ping through the VRF :
ping vrf Mgmt-intf <ip_addr>
Additionally, you can show the VRF route as followed :
show ip route vrf Mgmt-intf