This IP address matches the address of the interface a route was learned from, again not intended for interface-independent protocols like IBGP, with 0.0.0.0 meaning the attribute is unused. An admin uses it as an alternative to the interface index when identifying the ingress interface by its configured address. For example, setting csRtPolicyTermFromIntfAddr to a specific point-to-point link address scopes this term to routes learned over that particular link.