Where Do Users Want WAN Functionality Hosted?
Another WAN blog by Dr. Jim Metzler
This is the fifth in a series of blogs on the topic of the evolving enterprise WAN that is based on a survey that was completed in May 2016 by 110 network professionals. The previous blogs were:
- What’s Driving Change in the WAN?
- The Limitations of the Current Branch Office WAN Architecture
- How well do SD-WANs Support the Forces Impacting the WAN?
- When will SD-WANs be Broadly Adopted?
This blog will focus on the task of connecting users in a branch office to the external resources that they need to access and it will discuss the emerging alternatives for where the enabling WAN functionality can be hosted.
Traditional Branch Office WAN
The traditional branch office WAN architecture relies on a sophisticated, hardware-based router in each branch office as well as in each data center. In this approach, basic networking functionality such as connectivity to WAN services is provided by the router. Additional Layer 4 – 7 functionality, such as optimization and security, could be provided by the router or by external appliances. In either case all of the necessary functionality resides either in the company’s branch office or in one or more of their data centers.
As mentioned in What’s Driving Change in the WAN?, one of the key factors that’s impacting the WAN is the need to provide access to public cloud providers. While that is possible with the architecture described in the preceding paragraph, in many cases that architecture requires backhauling Internet traffic, which adds delay and cost. That is one of the reasons why currently there is so much interest in alternative WAN architectures.
What Are The New Architectural Options?
In contrast to traditional WAN architectures, in the emerging WAN architectures there are a number of places to host functionality such as orchestration, control and security. Those locations include:
- At the customer’s branch offices;
- In a service provider’s central office;
- At the customer’s regional office or data centers;
- In a cloud site provided by the SD-WAN vendor;
- At a co-location facility;
- At a public cloud provider’s facility.
Two of the key components of typical a branch office-focused SD-WAN solution are lightweight functionality in each branch office and control functionality housed somewhere. Depending on the provider, the control functionality can be housed either at one of the company’s internal facilities or at a public cloud facility. In order to secure the traffic that is destined for a public cloud provider, security functionality can be housed in a number of locations, including at that public cloud provider’s facility or at a cloud gateway which is located as close as possible to that facility.
An alternative WAN architecture is being advocated by Communications Service Providers such as AT&T. Similar to what was described in the preceding paragraph, these CSPs are advocating for lightweight functionality in each branch office. However, they are also advocating for hosting some or all of the L4 – L7 functionality that a branch office requires in one of their central offices that at least in theory is close to that branch office.
How Are These Alternatives Being Perceived?
The Survey Respondents were asked to indicate where their organization thinks that WAN functionality such as control, optimization and security should be located, and they were allowed to indicate multiple places. Their responses are shown in Figure 1.
As discussed in When will SD-WANs be Broadly Adopted?, although the majority of network organizations are either analyzing SD-WAN functionality or plan to in the near term, few organizations already have SD-WAN functionality in production. As a result we have to be careful in the conclusions that we draw from Figure 1. The data in Figure 1 does not show where network organizations will host WAN functionality. What it does show is their receptivity to where it is hosted and their opinions may change as they analyze alternative solutions. That said, Figure 1 indicates that at the current point in time that network organizations are receptive to a range of alternatives for where WAN functionality is hosted and that they are very receptive to hosting WAN functionality in the cloud.