The purpose of a VPN-ID is to uniquely identify a VPN.
The Global VPN Identifier format is:
3 octet VPN Authority, Organizationally Unique Identifier
followed by 4 octet VPN index identifying VPN according
to OUI
VPNIdOrZero
binary
This textual convention is an extension of the
VPNId textual convention that defines a non-zero-length
OCTET STRING to identify a physical entity. This extension
permits the additional value of a zero-length OCTET STRING.
The semantics of the value zero-length OCTET STRING are
object-specific and must therefore be defined
as part of the description of any object that uses this
syntax. Examples of usage of this extension are
situations where none or all VPN IDs need to be
referenced.