IOS XR Configuration

BEWARE! that configuration in IOS XR is hierarchical. What does it mean? Check the picture of basic configuring for OSPF. You specify the same thing on different levels. For example the network point-to-multipoint is above the area. That means that all interfaces in all areas that does not have anything configured will have this type. Then below the area 0 there is network broadcast command. This means that all interfaces within the area without any configuration for this will have this type. Then the interface Gig0/0/0/0.411 has the network point-to-point configuration. This overrides everything and this interface will have point-to-point type. So it is like tree which goes UP and configuration apply/is valid from the bottom to up. So this is especially important to know how this inheritance hierarchy works when we deal with BGP and VPNv4.

Also note that we didnt configure the ospf just under the interfaces, however we could. But then the OSPF configuration would be spread among the whole running config. This is nice because all ospf config is under the global „router ospf 1“. This is true about all the processes you want to configure in the ASR. For example LDP, etc. The physical properties of the interfaces like speed you configure under the interface itself, however the global properties you configure under the processes in global config.

hierarchy XR