GMPLS at-a-Glance

GMPLS home

MPLS has been widely recognized as the technology of choice in optical core networks because it can introduce traffic engineering to a variety of networking technologies, e.g., IP, ATM, and Frame Relay.

However, MPLS falls short of providing common control and traffic engineering for wavelength, TDM and fiber switching. The evolution of the optical network, as well as the need to support legacy networks, has generated the requirement for a more comprehensive and enhanced protocol.

Recently, a generalized version of MPLS, known as GMPLS, has been proposed to address this need and serve in a variety of network signaling layers, extending capabilities beyond those networks that are only packet or cell-based. For example, GMPLS claims to extend MPLS functionality by establishing and provisioning paths for:

• TDM paths, where time slots are the labels (SONET).

• FDM paths, where electromagnetic frequency is the label (light waves).

• Space division multiplexed paths, where the label indicates the physical position of data (Photonic Cross-connect).

GMPLS promises a seamless interconnection and convergence of new and legacy networks by allowing end-to-end provisioning, control and traffic engineering even when the start and the end nodes belong to heterogeneous networks.

GMPLS is an extension of the existing MPLS that supports TDM, wavelength and spatial switching. On of the main architectural enhancements proposed by GMPLS is the complete separation of the control and data planes of these various networking layers. While the technology used by the control plane remains IP-based, the data plane (traffic plane) can now diversify to include more varieties of traffic (TDM, Lambda, packet, etc). This architectural change will allow for high performance, intelligent networking while simplifying networks by combining transport and multiservice switching into a single layered network.

In summary, there are four functional elements to the proposed GMPLS:

• FSC Fiber Switch Capable
  

• LSC Lambda Switch Capable

• PSC Packet Switch Capable

• TDM Time-Division Multiplex Capable

New generation platforms supporting these four functional categories will give service providers an opportunity to migrate a new network architecture that will:

1. Allow overlay networks (TDM, Packet, Cell, Lambda) to evolve to a single layered architecture with a common control plane.

2. Allow end-to-end provisioning of services extending from the access network to the core.

3. Allow service providers to build multi-vendor networks with many of the integration and flow through issues simplified.

GMPLS at-a-Glance

New Network Architectures:

Two network models have been proposed:

1. Overlay Model: this assumes carriers will not expose their core network characteristics to the edge and/or the long haul sides. To facilitate this requirement, the OIF has proposed the optical UNI interface that allows provisioning/connection requests to be initiated from a "client" to the GMPLS-based "network". This model assumes separate routing domains.

2. Peer Model: this assumes service providers want to integrate their next generation GMPLS-based systems with existing legacy network elements to leverage the existing installed base. In this model an all-encompassing routing domain is used.

The ideal GMPLS-based system should allow service providers to build overlay or peer networks and there should support GMPLS and the OIF UNI interface.

Polaris Networks GMPLS Solution:

Polaris Networks, with its new generation optical transport switch solution, takes a leading position in the implementation of GMPLS:

1. Polaris supports the four aforementioned GMPLS functional elements (this is necessary since the system is multiservice (TDM, Packet, Cell and Lambda) aware. Using Polaris' solution can effectively open their networks to allow control and provisioning of any type of service.

2. In addition to the four categories, Polaris has also implemented further proprietary extensions to include ATM traffic management and path/flow trace capabilities. The ATM extension will allow service providers with cell-based backbones to gracefully migrate their networks to GMPLS.

3. Support for both the overlay networks as well as peer networks (OIF UNI), giving service providers the flexibility and choice of how to introduce GMPLS into their networks while allowing them to leverage their existing base.