when using Cisco GGSN&PGW combined gateway as an L2TP access concentrator for test apn the option "authentication msisdn-auth" for the APN works for 3G subscribers but it does not work for LTE subscribers because of PGW rejecting PAP authentication proposal from LNS during IPCP, if authentication type is set to none on the UE. Authentication is performed by RADIUS AAA server which either puts subscriber to the configured VRF or gives Tunnel attributes for L2TP by default if no profile is configured on AAA. We also tried nai-construction directive at the APN level and configured "aaa constructed-nai msisdn password cisco" at the context level. But without success. Why the behavior is different in our case for utran and eutran subscribers?
