Internal Network

A network where: (i) the establishment, maintenance, and provisioning of security controls are under the direct control of organizational employees or contractors; or (ii) cryptographic encapsulation or similar security technology provides the same effect. An internal network is typically organization-owned, yet may be organization-controlled while not being organization-owned.
SOURCE: SP 800-53

A network where
1) the establishment, maintenance, and provisioning of security controls are under the direct control of organizational employees or contractors; or
2) cryptographic encapsulation or similar security technology implemented between organization-controlled endpoints provides the same effect (at least with regard to confidentiality and integrity). An internal network is typically organization-owned, yet may be organization-controlled while not being organization-owned.
SOURCE: CNSSI-4009