GMPLS
Page 422 7450 ESS MPLS Guide
GMPLS
The Generalized Multi-Protocol Label Switching (GMPLS) User to Network Interface (UNI)
permits dynamic provisioning of optical transport connections between IP routers and optical
network elements in order 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 Alcatel-Lucent
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 thus 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.
Example Applications
This section summarizes some of the use cases that the GMPLS UNI may be used to address.
Use Case 1: Dynamic Connection Setup with Constraints
This use case aims to solve inefficiencies between IP and transport teams within an operator for
connectivity setup; for example:
• Process complexity, with complex database exchange, parsing and filtering
• Long-winded organizational communication prior to path establishment
It therefore aims to optimize IP/Optical transport team interactions by removing complex
processes, and reduces per-connection provisioning in the optical core.
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