<P> AP device operates inside the provider's core network and does not directly interface to any customer endpoint . It might, for example, provide routing for many provider - operated tunnels that belong to different customers' PPVPNs . While the P device is a key part of implementing PPVPNs, it is not itself VPN - aware and does not maintain VPN state . Its principal role is allowing the service provider to scale its PPVPN offerings, for example, by acting as an aggregation point for multiple PEs . P - to - P connections, in such a role, often are high - capacity optical links between major locations of providers . </P> <Table> <Tr> <Td> </Td> <Td> This section needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . (August 2016) (Learn how and when to remove this template message) </Td> </Tr> </Table> <Tr> <Td> </Td> <Td> This section needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . (August 2016) (Learn how and when to remove this template message) </Td> </Tr> <Dl> <Dt> Virtual LAN </Dt> </Dl>

Which of the following networking devices or services might not be compatible with vpn connections