A Cost-Effective, Scalable Network Architecture Approach
According to a recent Cisco Annual Internet Report (AIR), more than 70 percent of the global population – approximately 5.7 billion people – will have mobile connectivity by the year 2023.This connectivity includes 2G, 3G, 4G, and 5G. More than 66 percent of the global population will be Internet users. More users equate to more devices, all with an insatiable appetite for bandwidth to service their new business and consumer applications.
Some of the many bandwidth needs include video, online gaming, and virtual or augmented reality, challenging service providers with the need for high-density, high-bandwidth connections with low-latency performance requirements. Service providers therefore need to provide the bandwidth to support these requirements, but also meet stringent Service Level Agreements (SLAs) they demand.
Mr. Joachim Horn, Chief Technology and Information Advisor of PLDT and Smart Communications, the Philippines’ leading digital service provider, notes the realities of these challenges.
“With services being always on and customers expecting a consistent and superior level of experience, we are forced to relook at how we plan and design networks. We can no longer plan networks based on average load; we need to plan based on peak load.”Joachim Horn
Chief Technology and Information Advisor of PLDT
For operators to capitalize on this growth and generate new revenue, they must re-architect their network with an eye on efficiency and scalability, while reducing their Total Cost of Ownership (TCO). Efforts to make 5G scalability requirements cost effective is a primary focus of network operators. The effort requires keeping close track of production costs per Gigabyte on the network, and it needs to be considerably lower very soon.
Evolution of the same architecture isn’t enough. Technology continues to evolve with Application Specific Integrated Circuits (ASIC) development following Moore’s Law and Dennard Scaling Law, while optical continues to push Shannon’s limits. From an operational perspective, we see a strong push towards software with automation enabled by Software Defined Networking (SDN), telemetry, machine learning, and artificial intelligence. Network architectures continue to see evolution around multiple layers of the network, from packet to Optical Transport Networking (OTN) to Dense Wavelength Division Multiplexing (DWDM) layers. Each layer evolves around capacity and flexibility, along with added complexities.
Service providers must support the following objectives:
Meeting these objectives require focus on four key areas:
With these objectives in mind, providers must ask themselves if they can meet the demands of tomorrow with an evolution of their current network. Do they need to re-examine technology trends and rethink how to build their network to meet the objectives?
“For PLDT to meet the requirements of 5G, a new transport network was built (and) this transport network has huge capacity, commensurate with the invested resources on the radio network which is needed to commit to a consistent and superior customer experience,” adds Mr. Horn of PLDT. “The network needs to be more efficient and simplified, redundant layers removed, and the number of hops need to be reduced to allow for the most direct traffic path. At the same time, the network needs to allow for flexible placement of edge compute nodes for 5G low latency use cases. End-to-end network slicing capability is also key to support 5G services.”
Traditionally, the focal point for network designs was at the specific network layer required to deliver the service rather than the service itself. Networks were built with the layer focus due to where we were in the technology life cycle and meeting SLAs for the associated service:
Figure 1. Enabling high-capacity, service-focused network with total simplification
Networks today are hierarchical and Multilayered (ML) with each layer acting individually and operating on its own life cycle. These ML networks focus on the layer rather than the services due to technology limitations and the multiple services that require termination on different layers of the network. These network layers consist of OTN/TDM Switching, Packet Routing / Switching and DWDM / ROADM Switching to deliver these services as depicted in Figure 2b below.
These ML networks introduce complexity and redundant functions. The functions must be operationalized and have direct impacts on capital costs. Providers need simplified operations and cost-effective ways of delivering new and existing services with strong service-level agreements as well as enabling 5G and the associated new revenue generating opportunities.
Figure 2(a). Today’s hierarchical multi-layer network looks like this
Figure 2(b). Services terminate at different layers of the network. Each layer provides redundant functions, management, control, and life cycle management.
Technology is advancing, enabling innovation to address the challenges of today and meet future network requirements. These advancements include::
Figure 3(a). As interface data rates increase, a requirement for coherent technology at shorter reaches moves deeper into the network.
Figure 3(b). As coherent moves deeper into the network, adoption rates increase and within three years might be on par with 100Gig interface quantities.
SDN exists to address some of the complexities in operations, but the layers built into the network determine the complexity that SDN must overcome. Multilayer networks add an extra dimension of complexity from an operational life cycle perspective – the planning, protection, and managing of the network. As an example, existing Multi-haul solutions (currently deployed across Access, Metros, Long Haul, and Sub Sea systems) have greater flexibility to deliver higher capacity at optimal distances with greater than 6000 different set points. ROADMs have delivered on flexibility at the cost of complexity.
Figure 4. Projected technology enhancements through 2023
To deliver a network optimized around services that scale well beyond today’s capacity and performance requirements means taking advantage of innovations in technology. The 5G network architecture uses the following approaches to meet these needs:
The 5G Transport network provides simplification and enablement of true optimization as well as advanced service delivery. It supports not only the low-latency demands of new services and stringent 5G requirements, but also provides a future-proof, single-layered network.
Figure 5. Moving from a layer-centric approach to a service-focused network
As we continue to increase the data rates of the interface, we must contend with Shannon’s limits, which we’re already pushing up against. To overcome this, one of two things must take place:
Shortening the distance between endpoints occurs with a Hop-to-Hop (H2H) architecture. H2H allows true network capacity optimization with network simplification by collapsing network layers and eliminating the complexity and redundant nature of Multi-Layer networks.
Figure 6. Transition from the multi-layer network to the service-focused network in a Hop-to-Hop architecture or the 5G transport network
Figure 7 below provides a general comparison of three models for a network, with relative costs defined for the three different architectures:
Even though H2H requires more interfaces than either HC or OB, we see relative cost savings based on converging the layers, moving to simplified filtering structures, and using industry standard 400Gig ZR/+ interfaces. Based on modeling of real service provider networks for the different scenarios we see a relative savings in the order of 40% over a Hollow Core network and an approximate savings of 34% over an optimal bypass network. From the traffic-routing diagrams in Figure 8, you can see the simplification an H2H network brings to traffic routing, which provides overall simplification for the network and life cycle management.
Figure 7. Generalized depiction of Hollow Core, Optimal Bypass, and H2H networks with relative comparisons of architectures.
A 5G Transport architecture provides:
Figure 8. Model showing traffic routing and relative cost models for, from left to right, Hollow Core network, Optimal Bypass, and H2H.
Multi-layer networks have demonstrated their ability to meet the industry demands of today’s telecommunication service offerings. While demand for bandwidth continues to grow, the multi-layered approach of today’s networks restricts the service providers’ ability to advance their network. As technology has evolved to enable new ways of delivering services that meet the stringent service level agreements, service providers are re-examining the network architecture to create a more simplified network with reduced total cost of network ownership.
The 5G Transport architecture provides a simplified network by removing redundant layers, legacy technologies, and overlapping functionality. It provides unprecedented capacity and scalability, allowing customers such as PLDT to enhance customer experience. Segment Routing (SR) simplifies the underlay, making it easier to automate through a centralised SDN function and providing a more efficient operation. 5G networking of the future provides end-to-end network slicing and low latency while drastically enhancing customer experience and reducing the cost to serve.