[VPN] describes a method by which a Service Provider (SP) may provide a VPN service to its customers. In that method, BGP is used to carry customer routes across the SP's backbone. That method allows a variety of different protocols to be used as the routing protocol between the Customer Edge (CE) router and the Provider Edge (PE) router. [VPN-OSPF] specifies additional procedures to be used when the CE/PE router protocol is OSPF. In these additional procedures, customer OSPF routes from a CE router are translated into BGP routes by a PE router. Then they are sent via BGP to another PE router, which translates them back into OSPF routes and distributes them to another CE router. This translation may lose some of the information needed to prevent loops. This document proposes that one of the OSPF options bits be used to ensure that when a VPN route is sent from a PE to a CE, the route will be ignored by any PE which receives it back from a CE.