Virtualization Technology News and Information
VNF's Long Tail and the Need for Hybrid VM and CNF Environments

By Thomas Eklund, VP of Marketing and Strategy, Kaloom, Inc.

Since ETSI published its NFV white paper in October 2012, virtual network functions (VNFs) have proliferated among virtual machines (VMs) creating virtualized, or software defined, networks that can run on white box commodity hardware allowing them to be more pliable and cost-effective. Handling specific network functions such as routing, switching, firewall and load balancing, VNFs can be connected or combined as building blocks, called service function chaining, to create a fully virtualized networking environment.

Today, containerized open source orchestration systems such as Kubernetes are often a preferred method for greenfield deployments because of their lighter compute and storage footprints, portability, faster time to deployment, and other benefits. Containers, or Cloud-Native Network Functions (CNFs), are the new kid on the block and are beginning to replace VNFs in VMs with CNFs in containers to rapidly, efficiently deliver microservices across cloud and data center architectures.

However, many organizations have invested a lot of time and money in VM-based VNF solutions and architectures that are proven to work, and they are understandably reluctant to suddenly leap entirely from VMs into the new world of containers. Additionally, there may be other good reasons to keep certain networking functions in VM-based VNFs. This creates a need for networking solutions and architectures that can run both VM- and container-based  services and applications.

Hybrid 4G and 5G Networks

The need for solutions with these hybrid capabilities is drawn into focus with the deployment of 5G networks, which utilizes containers while existing 4G infrastructures continue utilizing VM-based VNFs. Because 5G is being deployed where the business case supports the need for, and expense of, new infrastructure investments, that means 4G environments will persist in certain areas for some time. Hybrid 4G and 5G infrastructures can be supported with a unified VNF and CNF data center networking architecture.

The rollout of 5G and its much higher speeds will enable new applications such as AR, VR, IoT/IIoT, autonomous vehicles, and many others. However, the performance requirements of these apps also create a greater need for more distributed edge data centers that put high-performance edge computing closer to the end user. 5G will require an order of magnitude increase in the number of data centers or central office environments than existing networks and many argue that 5G networks must utilize container-based microservices to support all of its different use cases and its services-based architecture.

5G and the Edge- It's Complicated

Infrastructure at the edge was already complicated enough before the advent of 5G. As shown in the below graphic, in a report on the challenges of Apps at the Telco Edge, IHS Markit states, "Our conclusion is that there are many edges, and we chose a fairly common definition of 20 milliseconds (ms) (round trip time = RTT) from the edge compute location to the end user, device, machine, or application. The two main drivers for deploying applications at the edge are latency and bandwidth efficiency."


Separately, in a blog on 5G, IHS Markit states, "The vision of one network handling and managing several networks is appealing in its elegant simplicity, but the steps needed to achieve such a vision are complex and manifold, requiring extensive time and resources to develop and implement."

In addition to much faster speeds, 5G specifications include many new features including native support for end-to-end network slicing, vEPC and user plane function (UPF) which defines and allows separation of the control plane from the data plane, supporting SDN and NFV. Another key element among 5G's specifications is support for cloud-native, or container-based, applications, and functionality.

Unifying VM- and Container-based Architectures

In telecommunications, the "Central Office" has traditionally been the place where networks converge to deliver services from a variety of switches and other equipment to enterprises and consumers via the local loop, or network edge. There are at least two well-established open source efforts working on virtualizing and simplifying this environment: OPNFV's Virtual Central Office (VCO); and the ONF's central office re-architected as a data center (CORD). These projects work to virtualize this environment, combining NFV and SDN to bring commodity data center economics and cloud agility to the telco central office. But what about enterprises, cloud, and data center operators?

These projects and others have added support for multi-vendor hybrid VNF and CNF environments to simplify and unify architectures to deliver similar tools and functionality to telcos, operators, enterprises, and their end-user customers.

Building on the success of VCO Demo 1.0 (covering enterprise and residential services) and VCO Demo 2.0 (adding mobile services), the joint effort is now exploring "VCO demo 3.0 that expands into areas such as full 5G, cloud native, and edge." Similarly, the ONF has created E-CORD which "builds on the CORD platform to create a cloud-native solution for delivering services to enterprise customers." Additionally, LFN recently released its Neon version of the OpenDaylight SDN controller which, among other things, "advances support for edge, cloud native, and downstream projects like ONAP, Kubernetes, and OpenStack." These are just three examples among many of open source groups and projects adding support for VM-, in addition to, container-based infrastructure.

According to OPNFV's initial solution brief, the enterprise VCO concept helps communication service providers (CSPs) deliver network services to their customers at up to 43 percent lower total cost of ownership (TCO). However, the real benefit of VCO for their clients is its ability to match the networks' capability to support the flexibility and speed of the cloud and by providing a unified architecture that can run across CSP, enterprise, and cloud and data center operator architectures.

The image below shows an example of a hybrid architecture where 4G VM-based VNFs run on OpenStack in the same systems that enable 5G container-based CNFs to run via OpenShift/Kubernetes. The VMs in 4G support its functions (EPC, MME and PCRF) while the CNFs support 5G's new native functions (UPF, SMF, AMF and PCF) as key elements of its service-based architecture. This hybrid 4G/5G use case is just one example that demonstrates a need to support both VMs and containers.


It is easy to imagine needing this type of hybrid VNF/CNF support where existing VM-based applications are already in place, but there are other reasons why firms may wish to use either VMs or containers to support disparate use cases that are better suited to one or the other environment.

In addition to supporting both VNFs and CNFs, the above graphic also shows a new type of virtual network architecture whereby the data plane is collapsed and offloaded and virtual functions such as vSwitch and vRouter are integrated into the fabric. Doing this has the potential to significantly lower latency, increase throughput and dramatically improve overall networking efficiency.

Solutions for a Hybrid & Heteregonous World

For a brief time during the public cloud's explosive expansion and price wars, some thought that the public cloud would take over and would eventually support all use cases and applications. But that did not happen. Instead the industry is trying to integrate a hybrid approach, working with multiple cloud providers, avoiding single cloud provider lock-in, while also leveraging their own private clouds for more secure applications and to manage costs. The need to support different use cases with varying technical needs led the market to the realization that hybrid cloud and multi-cloud were the more desirable solutions whereby applications are ideally placed in the cloud environment that best supports it.

Driven by disparate use cases, the need for customized apps, regulatory compliance, cost, flexibility, data security, or a host of other requirements, hybrid and multi-cloud environments will persist for some time. Similarly, while containers and the microservices they enable have significant benefits over VMs in that they will not replace VMs entirely as some applications may remain better suited to VMs, at least for now. So, we will continue to live in a hybrid world comprised of hybrid cloud, hybrid 4G/5G environments and hybrid VNF and CNF environments.

Service providers, enterprises, and cloud and data center operators are under pressure to ensure that their data center networks efficiently deliver high throughput at low cost and avoid bottlenecks. Overcoming this challenge makes networking the most critical piece for improving data center's overall application performance.

With a unified microservices and VM-based architecture, data center networking best serves whatever end user applications that need support and, in doing so, can finally not only match the speed and flexibility of the cloud but add value to it.


About the Author

Thomas Eklund 

Thomas Eklund is VP of Marketing and Strategy at Kaloom, Inc. Tom has a successful track record as an entrepreneur and as an executive, focusing on data driven businesses and networking. He has extensive experience operating global businesses, leading diverse cross functional teams and recruiting extraordinary talent to build and sell unique products.

Published Wednesday, September 18, 2019 7:33 AM by David Marshall
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