Although IP/Optical convergence is  not a new topic in the industry, the confluence of new market dynamics, the  resulting need for IP network modernization, and new technology innovations are  bringing it to the forefront of architecture evolution discussions.

From a communications perspective, the  landscape is fundamentally changing. Market dynamics associated with the changing  enterprise services mix, 5G, cloud—as well as residential and data center  connectivity—are creating new use cases and exciting revenue growth  opportunities for service providers. Consumer traffic flows are shifting  heavily toward the home to support Small Office Home Office (SOHO), gaming and  e-learning. Enterprises are accelerating their digital transformation and  moving toward Virtualized Network Functions (VNFs) and cloud applications,  including Software-Defined Wide Area Network (SD-WAN), to reduce costs.  Deployment decisions for 5G are beginning to pick up as providers evaluate  xHaul upgrade options and plan their evolution from 4G to 5G.

These market shifts are driving traffic  toward the edge of the network. From an applications perspective, this means  computing power will need to move from being centralized to becoming  distributed. Applications will continue to become virtualized and move closer  to end users, both human and machine, for reduced latency and improved QoE.  This will require cloud service termination and peering points closer to the  edge of the network. As a result, many service providers are in planning  discussions now about the creation of new metro and edge cloud on-ramp access  points. They’re also evaluating new technologies to be ready to support new  traffic flows—and the potentially exponential number of new services—expected over  the next several years.

The need to evolve the network to  capitalize on these new opportunities is driving IP network modernization. Key  elements of IP modernization include the evolution of access and aggregation  networks from L2 to L3 infrastructure, extending Layer 3 control plane into the  access, and transitioning to simplified end-to-end network service delivery using  Ethernet VPN (EVPN) for single service and Segment Routing (SR) for single  transport.  Another important aspect  under evaluation is IP/Optical convergence. In fact, according to a recent  study, 87 percent of providers view IP/Optical convergence as important or  critical for their next-generation networks.*

There are both hardware and software  tactics to IP/Optical convergence, and some or all of these can be employed to  achieve network simplification.  From a  hardware perspective, new technology innovations in coherent DSP and the  miniaturization of electro-optics are facilitating the integration of coherent  optics in router platforms through compact coherent pluggables that fit into  the same form factor as client grey optics, such as 100GbE and 400GbE. Two  popular form factors are being considered:

  • QSFP-DD for  high-capacity Ethernet aggregation and transport with no impact to router  switch density
  • CFP2-DCO for  higher performance and simple operation over existing ROADM infrastructure

As optics will make up more than 80  percent of the router cost moving forward, it’s important to select the  coherent plug whose capacity and performance is right-sized to match the  specific network use case.

Although the coherent QSFP-DD is equivalent  in physical size to client 400GbE optics, there are important differences.  Coherent QSFP-DDs enable DWDM transmission over long distance and the ability  to achieve 60x increase in fiber capacity; they also consume 5W+ more power due  to the more sophisticated DSP used for advanced modulation and electronic  compensation of impairments associated with propagation. For this reason,  coherent QSFP-DD pluggables are only supported on routers that have been  designed to support the additional thermal dissipation requirements.

Modern router and coherent pluggable examples

Image of a modern router and coherent pluggable

The 60x increase in fiber capacity is only achieved when the coherent  pluggable is combined with the appropriate photonic line system. An appropriate  line system design is selected to deliver the right flexibility and cost points  for the specific use case in the network. Integrated intelligence in these  platforms is important to accelerate and simplify service turn-up and  operations.

From a software perspective, a  cornerstone of next-generation architectures will be a centralized, SDN  multi-layer controller that provides a Path Computation Engine (PCE) and  advanced network applications. Streaming data telemetry and network analytics must  be used to guide the PCE and enhance operations. Together, these elements provide  advanced visibility, analysis, and service optimization as well as automated  path computation and provisioning. Open APIs are required to  expose network functionality to developers to  allow for rapid innovation and the introduction of new services. They also  enable easy access and integration with third-party devices which is essential  for practical deployment. Lastly, software convergence involves multi-vendor,  multi-layer management and resource optimization through a unified interface,  including planning, fault correlation, service resiliency and capacity  optimization.

Multi-layer management and resource optimization through a unified interface

A Multi-layer management and resource optimization through a unified interface diagram

We expect IP/Optical convergence to  remain a strategic topic of discussion for many service providers as they  evaluate the benefits of this architecture evolution. In fact, based on a recent  global service provider survey*, the following are selected as the top three  benefits service providers are seeking to achieve through IP/Optical convergence:

  • More streamlined  operation across IP and Optical layers (61 percent of respondents)
  • Full convergence  of IP and Optical functions including a common control plane (47 percent of  respondents)
  • Multi-layer  optimization using software optimization/automation (47 percent of respondents)

The path to IP/Optical convergence, and  realizing the above benefits, will be dependent on a service provider’s current  network reality and environment. But it’s clear that IP/Optical convergence is  set to play a key role in IP network modernization moving forward, holding the  promise of more cost-efficient, resilient, and unified networks.

Ciena’s approach to IP/Optical convergence is  grounded in the Adaptive Network™ vision and starts  with Adaptive  IP™—an automated, open, and lean way of delivering IP  differently, combined with  WaveLogic™ 5 coherent optics that can be use case optimized  to match specific network requirements. Ciena’s intelligent,  self-configurable photonic underlay enables flexible management of IP traffic flows while Ciena’s Manage, Control and Plan (MCP) and Blue Planet® software provide  intelligent network control to simplify and automate  multi-layer and multi-vendor operations using an open, cloud-native approach.

*Heavy Reading,  “IP and Optical Convergence Survey”, May 2021, n = 220