* L2TP APIs: see .../src/vnet/l2tp/{l2tp.api, l2tp_api.c}
* BFD APIs: see .../src/vnet/bfd/{bfd.api, bfd_api.c}
* IPSEC APIs: see .../src/vnet/ipsec/{ipsec.api, ipsec_api.c}
* L2TP APIs: see .../src/vnet/l2tp/{l2tp.api, l2tp_api.c}
* BFD APIs: see .../src/vnet/bfd/{bfd.api, bfd_api.c}
* IPSEC APIs: see .../src/vnet/ipsec/{ipsec.api, ipsec_api.c}