Packet Optical Networking

The core of the network is the workhorse that must handle the enormous amounts of data that are consumed by video, cloud computing and other popular bandwidth-intensive Web 2.0 applications. Yet, most core networks are still too inefficient and limited in bandwidth. Network operators need to rapidly adapt and increase network capacity. They also need to reduce their cost of deploying, operating and scaling optical core networks in order to keep margins strong. With the demand to shorten time-to-revenue and reduce operational expenses, increased network flexibility and lower operational complexity have become important areas of focus for cable operators. Next-generation architectures need to be defined which can cope with these challenges.

A new crucial milestone in optical networking has been reached with the evolution of Dense Wavelength Division Multiplexing (DWDM) technology to support a more flexible and dynamic agile optical core network infrastructure. DWDM networks are now evolving from a virtual fiber infrastructure into a true service provisioning solution.

The speed of data transported over a single wavelength has reached 100Gbit/s and will further scale. At the same time, new modulation schemes provide enhanced optical performance and reach. In combination with a new generation of optical components and devices, this technology simplifies network planning and therefore increases operational efficiency.

Next-generation Reconfigurable Add/Drop Multiplexer (ROADM) technology offers more dynamic and flexible options in operating optical networks. With this technology, new services can be provisioned without performing complex network engineering tasks. The additional integration of OTN and packet switching functionality has seen DWDM technology finally evolve into an intelligent and agile transport solution. The integration of packet-based forwarding and Ethernet service capabilities in particular contribute to the agility of optical transport technology, making multi-layer packet optical technology the ideal choice for innovative network infrastructures.

Figure 1 Multi-layer network architecture

Control Plane for Optical Transport Networks

An intelligent control plane starts to play an important role with the evolution of optical networks to a more flexible and dynamic multilayer service provisioning solution. A control plane offers a number of benefits. Control plane enabled agile optical networks support new, dynamic services including bandwidth-on-demand applications and customer-initiated service requests. The control plane also improves network efficiency and resiliency when applied for dynamic service restoration. Finally, the control plane helps to reduce operating expenses by simplifying service turn-up and network maintenance.

Generalized Multiprotocol Label Switching (GMPLS) is a standardized control plane technology for agile optical networks. It delivers effective traffic-engineering features and allows scalable growth. GMPLS also provides the necessary bridges between the IP/MPLS and optical layer. It enhances network agility by automating service turn-up and maintenance with auto-discovery, path computation and automatic provisioning capabilities to establish a service across the network.

Figure 2 Packet Optical Integration

The fundamental service offered by the GMPLS control plane is dynamic end-to-end connection provisioning. GMPLS is therefore elementary for a service-based network management approach. It operates on a multi-layer model and provides the basic automation procedures required for connection management. Network operators need to specify the service end points and the service profile parameters only. The control plane then determines the optimal path across the network and initiates the actions necessary to establish the connection across the corresponding nodes.

Multi-Layer Control Plane Applications

Packet optical networks implementing a multi-layer control plane that supports hierarchical network layer coordination enables operators to simplify network planning and operations while offering new, innovative services to their customers. The control plane also helps to establish a more accurate and reliable provisioning process. Sample applications include rapid service rollout, restorable services as well as service rerouting and network optimization.

  • Service Velocity: The multi-layer control plane provides a huge reduction in the provisioning process. New services can be established in real-time or can be set up automatically, for example, when requested by the IP/MPLS client layer.
  • Restorable Services: Unprotected services can be restored immediately after failure in meshed packet optical networks. The control plane determines a new valid path and re-provisions the service automatically. In combination with protected services this provides efficient prevention against multiple network failures.
  • Service Rerouting and Network Optimization: The adoption of a multi-layer control plane also supports network operators with automated network engineering and capacity management capabilities. Services can now be rerouted quickly, with fewer and less complex planning tasks. This capability simplifies ongoing network maintenance and optimization significantly.

Summary

DWDM networks have evolved from a virtual fiber infrastructure into a more flexible and dynamic agile optical core network solution supporting true multilayer service provisioning. Network operators need powerful, commercially viable and scalable solutions. A feature-rich GMPLS control plane implementation enables dynamic end-to-end connection provisioning and is elementary for a servicebased network management approach.

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