This IpAddress is the next-hop gateway address for a specific route entry, keyed by routingIndex (note the object name itself has a typo, 'Gatweway,' inherited directly from the vendor's original MIB). This is the actual next-hop IP that traffic matching routingDest/routingMask gets forwarded to, so an admin diagnosing a black-holed route checks whether this gateway address is reachable and correctly configured. A routingGatweway pointing to an IP that no longer exists on the network (e.g., after a router replacement) would explain traffic silently dropping for that destination.