The Generalized Multi-Protocol Label Switching (GMPLS) User to Network Interface (UNI) allows dynamic provisioning of optical transport connections between IP routers and optical network elements to reduce the operational time and administrative overhead required to provision new connectivity. The optical transport connections typically originate and terminate in an IP/MPLS controlled domain and traverse an intermediate optical transport network. The GMPLS UNI model is based on an overlay approach, whereby the IP/MPLS control plane is transported transparently over the intermediate transport network, which itself is controlled by a GMPLS control plane.
The UNI provides a clear demarcation point between the domains of responsibility of the parties involved in managing the overlying IP/MPLS network and the underlying optical network. For example, these parties could be two divisions in a service provider organization, or a subscriber/client of the service provider and the service provider itself.
The UNI has a client part, the UNI-C, and a network part, the UNI-N. In the Nokia solution, the UNI-C is an SR OS system, such as a 7750 SR or a 7950 XRS, while the UNI-N is an optical device; for example, an 1830 PSS.
Control plane related information is exchanged between the UNI-C and the UNI-N using a dedicated out of band communication channel. Note that the adjacent optical network element and the router assume that they are connected to a trusted peer, and therefore assume a secure communication. This is achieved by physically securing the link carrying the control channel between the two.
Based on standardized UNI messaging (RFC 4208), the UNI-C indicates to the UNI-N which far-end peer UNI-C node (corresponding to a remote router) to make an optical transport connection to. This path request can include additional path attributes to indicate requirements such as bandwidth, priority and diversity/resiliency parameters.