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SDN blogs: In the SD-WAN, centralized vs. distributed functions

In this week's SDN blogs round-up, analysts weigh centralized vs. distributed functions in the SD-WAN, and consider how to choose a networking start-up.

Centralized vs. distributed control plane functions in the software-defined WAN: Which makes more sense? Networking pro Ethan Banks breaks it down. Andrew Lerner has some tough questions for networking start-ups, and Greg Ferro tells us why the network command line is dying.

SD-WAN: Centralized vs. distributed functions

In a recent blog post, network architect Ethan Banks explores the issue of centralized vs. distributed functions in the software-defined WAN (SD-WAN).

Banks writes that in a perfect software-defined world control plane functions would all be centralized. In the real wide area network (WAN), however, total centralization can create performance issues, such as higher latency. Any controller outage could also bring the entire WAN to a halt, or at least force the network to operate "headless," continuing to forward traffic in accordance with the last direction received from the controller.

Banks writes that SD-WAN architectures should place performance goals ahead of theoretical ideals -- centralizing functions only if doing so will ultimately improve the network for the user. Banks cites Cisco's IWAN as an example, saying it centralizes some functions to simplify operations and increase agility, but keeps others distributed to minimize delays and improve scalability.

Banks shares other thoughts about SD-WAN management on his blog.

Questions to ask a networking startup

Considering an SDN or SD-WAN networking startup to provide your organization with new services or technology? Gartner Inc. analyst Andrew Lerner has some questions to ask before signing on the dotted line. He reminds Gartner blog readers that it's easy to fall prey to "shiny new object syndrome," seduced by the promise of a technology cure-all. To maintain a level-head and gain insight into a new vendor's long-term viability, he recommends asking suppliers the following questions:

  • How many paying customers do you have?
  • What is your funding and revenue?
  • How many employees do you have?
  • Who are your friends/partners?
  • What's the differentiation?
  • Who is your buyer?
  • Tell me about deals you've lost.

Lerner suggests looking for signs that a start-up has significant traction with investors and technology partners. A new vendor should also possess a strong understanding of the existing market, clearly differentiating itself from incumbents. To read more about what to look for in a networking startup, check out Lerner's full post here.

RIP, command line?

On his blog, Ethereal Mind, Greg Ferro predicts that network professionals' use of the command line will atrophy in the coming years, thanks in part to network virtualization. In a hardware-driven architecture, he writes, physical limitations keep the number of network devices in check. With the rise of virtual devices, however, total device counts will explode -- making manual command line interface (CLI) configurations inefficient and impractical. 

A caveat: Ferro writes that, while day-to-day network operations won't occur via the CLI, high-level engineers will continue to use it to deploy and troubleshoot individual devices. In other words, the network command line may be dying, but it's not dead yet.  

Read Greg's full post here.

Next Steps

SDN: Centralized or distributed architecture?

How SDN reduces reliance on the CLI

What you need to know about SDN startups

Dig Deeper on Software-defined WAN (SD-WAN)