Software to the switch: Redefining data centre networking

William Scull

Wednesday 12 July 2017

Networking is catching up with the rest of data centre technology. Lenovo’s innovative Cloud Network Operating System (CNOS), based on open standards, simplifies programmability, hypervisor control and automation tools integration – all from a single, easily managed point of control.

As with servers and storage, control of data centre network hardware is moving into the hypervisor software layer, thus enabling networks to be created and managed in ways similar to those already used to manage virtual machines (VMs) and virtual storage. As the network is migrated to centralised software control, it makes the fully software-defined data centre (SDDC) more of an operational reality.

To position itself at the forefront of this development, Lenovo created an entirely new network operating system called CNOS. This is not a refined version of the predecessor Enterprise NOS; CNOS was written from scratch, based on the Linux OS, which makes it much easier to create programming links to open-source tools and standardised software for orchestration and provisioning (both most often based on Linux).

Simpler network device reach and programmability

The IT industry is progressing to common software provisioning tools, based on open standards, and these simplify hybrid cloud design and the integration of networking resources in data centres. This move was pioneered by the hyper-scale ‘mega’ data centres, whose recommendations on open platforms like the Open Compute Platform (OCP) are being deployed in enterprise-size data centre facilities.

Lenovo’s CNOS provides a simple, open and programmable network infrastructure designed to scale as required. Being based on open Linux standards that support common automation and orchestration applications enables simple and exceptionally tight data centre integration.

The entire networking stack follows the same design principles as compute and storage to enable scale-out and automation readiness. CNOS thereby allows Lenovo switches to be more easily controlled by hypervisors and other software management tools, making networking as software-definable as server and storage resources. 

Better automation and switch management

The consumption model of an integrated networking stack can be also be leveraged for other hyper-converged and software-defined solutions with open networking. This makes it easier for customers to deploy web-scale architectures from a single management ‘pane’ for other products. CNOS here is, in effect, an enabling technology for the integration of the network switches into the general data centre management tools already in use.

Automation brings other benefits. It limits resource demand, reduces errors and helps data centre administrators manage more elements. With CNOS, existent automation tools and DevOps practices can also be utilised for networking.

The provisioning tool Ansible is a good example of this. Ansible is an open-source automation engine that automates cloud provisioning, configuration management and application deployment. By having the system intelligence abstracted in higher-level software tools, and change management occur in the logical software layer rather than directly on the hardware, CNOS is able to facilitate more direct control and configurational simplicity.

The required vendor module for communication with the Ansible-controlling software server is ready-integrated into CNOS, so automation and provisioning tasks can be defined on the Ansible server and executed on the hosts (i.e. Lenovo networking switches). Ansible can also be used to provision servers.

Achieving hyper-convergence’s true potential

By coupling CNOS with hyper-converged systems such as Lenovo HX Series powered by Nutanix software, customers can move beyond traditional ‘siloed’ data centre resource constraints, and can simplify and aggregate compute and storage resources. True hyper-convergence, however, should include network functions. Using the policy-based network deployment agent feature of Nutanix, CNOS integration allows the network infrastructure to be discovered and configured directly from the Prism management tool without the need to directly access the switch command-line interface. From Prism, the virtualisation administrator can perform basic tasks like VLAN creation without the need to request this from the network team; thus enabling control and monitoring of all data center elements – storage, server and network –  from a single centralised tool.

In addition, it can ensure that networking parameters stay ‘bound’ to a VM when it moves within the cluster, without manual intervention needed. The required software to link to the Prism interface is part of CNOS*, and it can be implemented now – this function will shortly be included as part of the converged solution, called the Lenovo ThinkAgile Network Orchestrator.

* Now available for Acropolis KVM  hypervisor, planned for ESX and Hyper-V

Improved OpenStack configuration

OpenStack is an open-source infrastructure initiative for the creation and management of large groups of virtual private servers in cloud computing environments. To build OpenStack clusters, customers continue to take advantage of the open standards for compute and storage. Networking in such environments has historically been more challenging, but this is changing.

Neutron is an OpenStack project that aims to provide ‘networking-as-a-service’ (NaaS) between interface devices managed by other OpenStack services. Lenovo now offers a solution to allow its switches to be configured from this ‘orchestration’ software. Lenovo’s networking Neutron plug-in provides a means to orchestrate virtual LANs (VLANs) on Lenovo’s physical switches. In cloud environments where VMs are hosted by physical servers, the VMs see a new virtual access layer provided by the host machine. This new access layer can typically be created via many mechanisms – for example, Linux Bridges or a virtual switch.

The policies of the virtual access layer (virtual network) when set must then be coordinated with the policies set in the hardware switches. Lenovo’s Neutron plug-in helps coordinate this behaviour automatically without manual intervention from the data centre administrator.

Steps toward a software-defined networking future

These are just a few examples of the growing software-defined solutions brought forward by Lenovo, including the integration of all networking hardware products. Similar solutions for Microsoft, VMware and SUSE are already available or in development. The intrinsically open nature of CNOS guarantees that these solutions will be the beginning of ever-tighter, ever-innovative integration between hardware infrastructure and data centre software tools.


Building the next-gen data centre

Where traditional and web-scale apps co-exist