What is edge networking?
Edge networking consists of the access and aggregation elements of the transport network. In our context, we are referring to the mobile edge network and transport over a fiber optic plan. The mobile edge network is from the cell site to the core. The mobile edge mainly consists of a Distributed RAN, or D-RAN, and also consists of a D-RAN blended with Centralized RAN, or C-RAN. In a 5G C-RAN topology, the electronics or distribution and central units are separated from the radio at the cell site and centralized at a remote location within the latency limits of the RAN.
This transport segment is the fronthaul. If the distribution and central units are also separated, this transport segment is the midhaul. The D-RAN is where all the RAN elements are co-located at the cell site: the radio, distribution, and central units. The transport segment from the cell site to the core is the backhaul. Edge networking takes place in the backhaul and midhaul segments and in addition to the RAN elements, there are also a compute and storage devices referred to as the Mobile Edge Compute, MEC, or Multi Axis Edge Computing.
Types of edge networking topology
The edge networking traffic is transported between the RAN, MEC, and core devices. This traffic uses layer 3 Internet Protocol (also referred to as IP) or to a lesser extent layer 2 carrier Ethernet Protocol is used. Groups of these cell sites are combined at aggregation sites for traffic consolidation and fiber relief to the core. The interconnection between the access and aggregation sites varies based on fiber availability. The edge networking topology can be hub and spoke with dedicated 10Gb Ethernet spokes at each cell site or in the preferred ring topology.
In a ring topology, all the cell site capacities are cumulative on the fiber ring and statistically multiplexed yielding ring rates at 100 Gb Ethernet, ultimately scaling to 400 Gb Ethernet. Ring topology has its attributes as it is easier to deploy short fiber segments between cell sites than home runs from each cell site to the aggregation site. Also, ring topology offers fiber path resiliency for higher service availability.
In summary, edge networking has two critical points: access at the cell site and aggregation at cell sites in that general region. Information is transported between RAN, MEC, and core elements in the midhaul and backhaul and predominantly uses IP routers in a hub and spoke or ring type of topology at up to 400 Gb per second line rates.
Edge networking and RAN virtualization
Fujitsu recently co-sponsored a global survey with Heavy Reading. Quoting from the global operator survey, Operator Strategies for 5G Transport, “Cloud/virtualized RAN tops the list of priority initiatives network operators expect to implement over the next three years.” Almost 60% of global operators surveyed expect to implement RAN virtualization. Local hub sites and cell sites are expected as primary locations and later deployments at edge data centers.
Just under half of the operators surveyed plan on implementing network slicing. Network slicing within these networks provides a single agile virtual network for disparate service delivery applications. Operators also responded in the survey with the top three services being disparate offerings: Wholesale services such as enhanced Mobile Broadband (eMBB), enterprise services like Machine-to-Machine Type Connectivity, and verticals in healthcare, finance, and smart cities needing Ultra-Reliable Low-Latency Connectivity (URLLC). With regard to capacities, 5G per cell site backhaul capacity is at 10 Gb per second.
Edge aggregation and backhaul networks
The Heavy Reading survey also found just over two thirds of operators expect that at least 100 Gb of capacity will be required in the backhaul and aggregation, and nearly as many expect greater than 100 Gb per second will be needed for edge access. Although 10 Gb per second to an individual cell site will be sufficient for backhaul, operators expect to carry traffic from multiple cell sites, such as ring topologies.
These survey results provide strong support that 100 Gb per second and even 400 Gb per second will play major roles in edge aggregation and backhaul networks over the next several years.
Fujitsu edge networking solutions
Fujitsu’s Smart Edge optical solutions toolbox consists of an extensive edge router portfolio and optical ecosystem optimized for edge networking and network slicing in both indoor and outdoor form factors. The edge networking portfolio consists of the OcNOS (Open Compute Network Operating System) access and aggregation whitebox routers. Whitebox routers are the next-generation transport elements, which are disaggregated. In this context of disaggregation, network software is separated from the switching or routing hardware and partitioned into functional components that can be more efficiently operated. Programmability, automation, and agility with better control of their networks are immediate benefits of disaggregation for operators, besides potential cost savings. These platforms flexibly adapt diverse traffic flows, supporting a growing variety of use cases, such as urban and rural mobile transport.
Utilizing OcNOS whitebox routers
The result is an open transport portfolio that can easily integrate into the open management and orchestration standards for end-to-end operation with Virtual RAN, MEC, and core elements. Compact, modular, low power design, yet high capacity for sites where footprint is at a premium. Precise frequency and phase/time synchronization is also fully integrated. As data demands grow, the OcNOS portfolio provides smooth scaling line capacity from 1 Gb Ethernet to 400 Gb Ethernet on the same platform. The cell site routers provide 5G eCPRI along with data service access and fiber-relief at throughputs up to 800 Gb per second and aggregation routers with up to 4.8 Tb per second throughput for hub/spoke and ring topologies. The OcNOS service provider whitebox routers offer best of breed performance along with the Virtuora Network Controller for end-to-end management and control.
