GMPLS Unified Network Layer

Carriers are integrating IP and optical network technologies to improve service efficiency and develop advanced services. But first, they need to overcome extremely complex multi-layer architecture. This architecture is "poorly pieced together to deliver IP services over a network designed to support voice and fixed circuits. Finally, they also need a control platform that extends from the third-layer IP address to the First-layer optical transport layer.
The general Multi-Protocol Label Switching (GMPLS) is developed to meet this need. It expands the network intelligence in a unified control plane: from the network edge to the network core, then return to the edge.
As a recommended IETF standard, GMPLS is still under development and is not expected to be deployed on a large scale within one or two years. However, this technology is not entirely new because it is based on the many achievements made in the development and standardization of Multi-Protocol Label Switching (MPLS. MPLS simplifies the network architecture by replacing the need for ATM and frame relay devices to monitor traffic engineering.
MPLS creates a virtual tag switching path (LSP) on a network composed of a tag switching router (LSR) to improve IP availability and service quality. The main extension of GMPLS to MPLS is its ability to establish connections at the first layer.
GMPLS can be deployed in either of the following ways: overlay model or peer model ). In the coverage model (also known as UNI), a router is a Client Connected to the optical region and only deals with adjacent optical nodes. In the coverage model, the actual physical optical path is determined by the optical network, not by this router.
In the peer-to-peer model, the IP/MPLS layer is fully equivalent to the optical transport layer. Specifically, the IP router can determine the entire connection path, including the path through the optical device.
The goal of the Peer-to-Peer Model and the coverage model GMPLS is to extend the MPLS range from the router to the optical domain. In optical fields, the forwarding decisions are made based on the time slot, wavelength, or physical port, rather than based on the group boundary. GMPLS supports this type of cross-origin equivalence by supporting new LSR (including dense wavelength division multiplexing, add/drop multiplexing, and optical cross-connection. The most important aspect of GMPLS is how it affects request and distribution tags, how bandwidth is allocated, and how it notifies network failures.
GMPLS uses the Internal Gateway Protocol (IGP) Extension to support different link types: Normal, ungrouped, and forwarded connections that are input to the link status database. If the nodes at both ends of the link can receive and transmit packets, GMPLS determines them as normal links. If not, they become non-grouped links. If an LSR creates and maintains a tag exchange path (LSP), it can declare this LSP to IGP as a forwarding connection.
The key to this method is the LSP hierarchy defined by GMPLS. This enables the nested LSP to support the establishment of transmission trunk lines. This feature is similar to MPLS's support for the tag stack feature. In the tag stack function, many smaller LSPs can be clustered into a larger LSP. The running mode of GMPLS is basically the same as that of the LSP represented by the virtual physical path.
In the layered system established by GMPLS, the LSP starting and ending with a group exchange node is at the bottom, above it are LSP connected to the TDM switching node, LSP connected to the optical wavelength switch, and LSP connected to the optical fiber switching node.
GMPLS will help service providers dynamically supply bandwidth and capacity, improve network recovery capabilities and reduce operating costs. GMPLS may also bring new revenue-generating services such as optical VPN. Another expected benefit is GMPLS's support for open standards, which will allow carriers to use the most advanced equipment when building their networks.
The demand for GMPLS will grow with the increase of IP transmission streams and services. However, challenges still exist. Vendors need to establish business cases that support introducing GMPLS. If enterprises want to achieve maximum efficiency, they must overcome their own organizational barriers to separating optical transport from IP management domains.

Translated from Network World)