Software Defined Networking - "The Biggest Thing Since Ethernet"

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Network-Aware Orchestration: The Next Level of SD-WAN By @SDietric | @CloudExpo #Cloud

Enterprises need to be aware that deep cultural changes are needed

Enterprise networks have become complex. They were designed and deployed to meet a specific set of business requirements at a specific point in time. Configuration modifications were rare, and manual or semi-automated processes together with strict change control procedures were enough to maintain reliability and consistent service levels across the organization.

Business needs have shifted dramatically. The adoption of cloud services, business application-focused requirements and evolving security policies require IT organizations to continuously deploy configuration changes. The common approach of either manually performing changes necessary or simply replacing the complete device configuration, rebooting and hoping it will function, creates unacceptable risks and potential network interruptions. Therefore, enterprises are looking for better ways to automate the management of their networks through leveraging existing capabilities to optimize performance and reducing operational risk through standardization and best-practice architectures.

Software-Defined Networking
Software-defined networking (SDN) promises just that: to provide network configuration management via software to make a network more agile and adaptable. With SDN, all network configurations are stored and managed centrally, and devices can be reprogrammed as needed on the fly, simplifying hardware infrastructure and administrative overhead. This allows enterprises to free up network expertise from mundane tasks and to refocus on business-critical optimization tasks and enables smaller organizations without deep networking engineering expertise to implement much more sophisticated network architectures.

Extending SDN from Data Centers to the WAN
Software-defined networking started in data centers and proved the benefits of developing software to automate network management. In addition, network function virtualization replaces many physical network devices by their virtual counterparts running on commodity hardware. This increases the capabilities to custom program, scale and chain network services to anticipated needs, especially for complex services such as load balancing, firewalling, intrusion detection and WAN acceleration.

While managing this complexity for data center, where technology is chosen by the enterprise, was already difficult, WAN connectivity provides an additional layer of complexity. Network services are bought from service providers who use their own architectures and technologies that may vary by location. Many businesses have also started to rollout VPN solutions over Internet broadband as cost-effective replacements for private MPLS lines for almost all business applications, save for those that are the most sensitive and business-critical.

Through SD-WAN, it is now possible to create a transparent logical enterprise IP network across service providers' technologies, architectures and service offering, and add advanced network features such as application-based traffic routing or custom security provisions meeting strict compliance requirements and optimizing utilization of existing network capabilities while maintaining SLA. By logically untangling the existing mesh of legacy WAN networks, cost savings can be realized from leveraging Internet broadband and cellular data as cost-effective alternatives to private circuits on a global scale on one simplified overall architecture. However, managing such a network on top of various underlying network architectures-at scale-remains difficult, and SD-WAN overlay networks per se can not address physical poor-performing WAN connections; hence, ensuring a well managed underlying network architecture at the same time is key.

Common Approaches to SD-WAN
Several SD-WAN vendors exist in the market with particular focus and strength. In general, they can be classified as follows:

  • Appliance-based overlay solutions that create a virtual IP network between the vendor's appliances across any network, combined with vendor specific management tools.
  • Controller-based solutions that can auto-discover and configure network devices; and
  • Advanced automation and change control solutions that can enable and manage SD-WAN and the underlying infrastructure by leveraging existing hardware.

Each of them has specific advantages and disadvantage that position them in the SD-WAN market: Overlay solutions are attractive for many because they can be deployed quickly, but they may lack sufficient customizations or create additional complexity for troubleshooting. Controller-based solutions work effectively when environments are highly standardized. Network automation and change control solutions can address high customization requirements but may need additional time for implementation.

Can You Trust Your SD-WAN to Perform?
The challenge for enterprises is how to make a successful transition from the current state to the fully automated and integrated SD-WAN network of the future. Existing change control mechanisms are often ill-equipped to handle the complexity during transition. Especially with manual processes involved, configuration mistakes are unavoidable, and even the most elaborate testing may not find rare conditions that only reveal themselves when the network is under load at the most critical times.

Formal or independent verification and validation for networks is difficult. While computer code can be validated through notational or operational semantic methods to ensure correctness for all possible conditions, such analytical approaches are unpractical for business use, given frequently changing customization requirements. Therefore, enterprises are looking for network automation that will not only provide the capabilities to implement and maintain a logical IP network but also the capabilities to manage the underlying infrastructure, implicitly verifying and validating implemented architectures, detecting hidden dependencies and understanding the full impact of any change.

Network-Aware Orchestration Is Needed
Though all SD-WAN solutions create logical IP networks and make their management easier, to ensure that the network will perform optimally, they must also provide the next level of operational capabilities such as network-aware orchestration, with functionality such as:

  • Built-in proven, best-practice architectures for initial provisioning
  • Understand the network impact of any change ("network-aware")
  • Apply changes "in concert," understanding architectural dependencies
  • Resolve any hidden dependencies automatically when possible
  • Apply changes with minimal impact (e.g. avoid unnecessary reboots)
  • Monitor the configuration state of all devices in the network
  • Validate changes have been successfully applied or revert when needed
  • Limit direct manual access through a verifiable audited interface

With such advanced management and automation, additional verification and validation of the network can be performed, providing a solution that the network is in fact correctly configured and that, for example, any non-authorized manual changes are pro-actively detected and remediated swiftly.

Making the Transition
Moving from traditional networking to SDN is as much a technical as it is a cultural and organizational challenge. Nearly everything will change: initial network provisioning, configuration and change management, troubleshooting procedures, performance monitoring, and security, compliance and audit validation and verification.

In addition, as SD-WAN will simplify and bring more standardization across the network, there will also be increased requirements for specific customization when needed. Software developers need to align closely with network operations staff to understand in detail the requirements to be implemented addressing specific operational needs. This approach, generally referred to as "DevOps" has already proven faster time to market, better customization, fewer failures and more rapid recovery from negative events or misaligned changes.

Looking Ahead
Enterprise WANs will continue to grow, and complexity will increase. The ability to implement an SD-WAN solution that provides not only the technical ability to create a logical IP network but also related network automation and change management capabilities on the underlying network are critically important to ensure that the network will perform under critical loads.

Enterprises need to be aware that deep cultural changes are needed. "The way things have always been done" will no longer work. New tools are needed to manage the underlying heterogeneous service provider network technologies on the WAN, providing implicit application of validation, verification and remediation procedures to detect potential error conditions early. Those network-aware orchestration capabilities on the underlying infrastructure are critical and represent the next level for SD-WAN solutions, and they will deliver the network agility enterprises are looking for to compete in today's economy.

More Stories By Stefan Dietrich

Dr. Stefan Dietrich brings to Glue Networks more than 20 years of experience defining innovative strategies and delivering complex technology solutions. Before joining Glue Networks, he was Managing Director of Technology Strategy at AXA Technology Services, introducing advanced new technologies to AXA globally, and held senior IT management positions at Reuters and Deutsche Bank.

Stefan received a Ph.D. in Aerospace Engineering and Computer Science from the University of Stuttgart and served as a Postdoctoral Fellow and faculty member at Cornell University.

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