Here is a list of all namespaces with brief descriptions:

[detail level 123]

Nvapi	Forward declarations
▼NVOM	The VPP Object Model (VOM) library
▼NACL
Nacl_ethertype_cmds
Nbinding_cmds
Nlist_cmds
Narp_proxy_binding_cmds
Narp_proxy_config_cmds
Nbond_group_binding_cmds
Nbond_interface_cmds
Nbridge_domain_arp_entry_cmds
Nbridge_domain_cmds
Nbridge_domain_entry_cmds
Ndhcp_client_cmds
Ngbp_bridge_domain_cmds
Ngbp_contract_cmds
Ngbp_endpoint_cmds
Ngbp_endpoint_group_cmds
Ngbp_ext_itf_cmds
Ngbp_recirc_cmds
Ngbp_route_domain_cmds
Ngbp_subnet_cmds
Ngbp_vxlan_cmds
Nhw_cmds
Nigmp_binding_cmds
Nigmp_listen_cmds
Ninterface_cmds	Forward declaration of the stats and events command
Ninterface_span_cmds
Nip_punt_redirect_cmds
Nip_unnumbered_cmds
Nl2_binding_cmds
Nl2_emulation_cmds
Nl2_vtr
Nl2_vtr_cmds
Nl2_xconnect_cmds
Nl3_binding_cmds
Nlldp_binding_cmds
Nlldp_global_cmds
Nnat_binding_cmds
Nnat_static_cmds
Nneighbour_cmds
Npipe_cmds
▼Nroute	Types belonging to Routing
Nip_mroute_cmds
Nip_route_cmds
Nroute_domain_cmds
Nsub_interface_cmds
Ntap_interface_cmds
Nvxlan_gbp_tunnel_cmds
Nvxlan_tunnel_cmds