In the beginning there was IBM's SNA (System Network Architecture). OK, you could argue that SNA was not the beginning of wide-area networking, but it certainly was one of the first formal, widely deployed WAN architectures. SNA was initially designed to support primarily low-speed data entry applications. Given the demands of those applications, and the transmission services that were available at the time, one of the cornerstones of SNA was 9600-baud analog multipoint private lines.

When the Internet was first being deployed, it was intended to support e-mail traffic between a handful of research institutions. As a result, Internet protocols such as TCP were designed to support that goal. In particular, key features of TCP, such as congestion control, reflect both that goal as well as the characteristics of the transmission services that were available at the time.

The bottom line is that WANs have always been designed to reflect the requirements of both the applications that they are intended to support and the available transmission services. With that in mind, the next couple of WAN newsletters will discuss how the mix of applications that transit the WAN is changing to provide insight into how the WAN has to evolve. These newsletters will draw on a report entitled “The Application Usage and Risk Report” that was recently published by Palo Alto Networks.

The report details the application usage of 60 large organizations between April 2008 and July 2008. The report identifies the 428 applications that are running on the 60 WANs and points out that 56% of the applications used HTTP either as its underlying protocol or as a means of tunneling other applications. In addition, HTTP-based applications consumed 64% of all of the bandwidth.

It is common to associate HTTP traffic with browsers. However, the report clearly points out that many client-server applications such as Microsoft’s SharePoint use HTTP and that the majority of HTTP traffic on the 60 networks was in fact generated by client-server applications.

One of the key challenges associated with the increased use of HTTP is the fact that most WAN firewalls do not inspect HTTP traffic. That leaves IT organizations without any visibility into this traffic and hence leaves IT organizations vulnerable to the impact of this traffic. For example, HTTP traffic could be supporting a key business application such as SharePoint. It could, however, also be transporting AOL instant messaging which supports file transfers. Perhaps those files being transferred in and out of your company on your WAN are benign, but perhaps they are transporting a nasty virus. IT organizations will not be successful if they continue to be blind to the traffic that is transiting their WAN.

Steve Taylor is president of Distributed Networking Associates and publisher/editor-in-chief of Webtorials. Jim Metzler is vice president of Ashton, Metzler & Associates.