The Limitations of the Current Branch Office WAN Architecture
Another blog in the series by Dr. Jim Metzler
This is the second in a series of blogs on the topic of the evolving enterprise WAN that is based on a survey that was completed earlier this year by 110 network professionals. The first blog in this series, Main Change Drivers in the WAN, discussed the level of satisfaction that enterprise organizations have with their current WAN architecture and identified the factors that are having the biggest impact on enterprise WANs. This blog will discuss how well the traditional branch office WAN architecture responds to those factors. Subsequent blogs will look at topics such as the factors driving and inhibiting the adoption of SD-WANs, the varying approaches that enterprises are taking to evaluate SD-WANs and the varying implementation and architectural options enterprises are considering.
As was mentioned in the previous blog, one of the factors that is currently having the greatest impact on enterprise WANs is the growing need to provide access to public cloud services. Since in the vast majority of cases the Internet is used to provide access to these services, supporting the growing need for access to public cloud services is just one reason why the vast majority of companies continue to see steep increases in the volume of their Internet traffic.
A key characteristic of the traditional branch office WAN architecture is to have T1/E1-based access to a service provider’s MPLS network at each branch office and to have one or more high speed links at each data center. In this architecture it is common to backhaul some or all of a company’s Internet traffic to a data center before handing that traffic off to the Internet. In order to understand how common this architectural approach is, the survey respondents were asked to indicate how much of their Internet traffic that is generated in branch offices is backhauled to a data center before being handed off to the Internet. In Figure 1, the graphic labeled 2016 shows how the recently surveyed network professionals answered that question and the graphic labeled 2015 shows how a similar set of network professionals answered that question a year ago.
Figure 1: Internet Traffic Backhauled to Data Center
One observation that can be drawn from Figure 1 is that over the last year there has been a modest decrease in terms of how much Internet traffic is backhauled. Another observation is that there is a bimodal approach to how Internet traffic is handled. Thirty-five percent of organizations backhaul 20 percent or less of their Internet traffic while the same percentage of organizations backhauls more than 80 percent of their Internet traffic.
As highlighted in What’s Driving Change in the WAN, three other factors that are having a major impact on the enterprise WAN are:
- Increase security;
- Reduce cost;
- Support real-time applications such as voice and video.
Based on supporting those three factors, the current architectural approach of backhauling Internet traffic gets at best mixed reviews. Backhauling traffic tends to increase security because sophisticated security functionality can efficiently be applied to this traffic in the data center. However, because backhauled traffic transits both the MPLS network and the Internet access link it adds cost. This approach also adds delay which can make it more difficult to support real-time applications.
As mentioned, future blogs in this series will look at how network organizations currently view SD-WANs. One question that those blogs will answer is; do network professionals think that SD-WANs can reasonably support all of the factors that are impacting the enterprise WAN or will SD-WANs also get mixed reviews?