There are a number of differences between local- and wide-area networking. One obvious difference is speed: many IT organizations are in the process of upgrading their data center LAN links from 1 Gbps to 10 Gbps, and they’re aware that 40 Gbps and 100 Gbps technology is under development. In contrast, due to the prohibitive cost, few IT organizations run more than a couple of their WAN links at 10 Gbps or higher. Another notable difference between the LAN and the WAN is latency: in the vast majority of instances, the minuscule amount of jitter and packet loss that the LAN exhibits doesn’t have an appreciable impact on application performance. In contrast, the latency, jitter, and packet loss that the WAN exhibits often has a significant impact on application performance. Perhaps the biggest difference, however, between the LAN and the WAN is that there is a wide array of fundamentally new technologies being developed for the LAN. As I will discuss below, that is not the case for the WAN.
The Internet got its start in 1969 with the deployment of ARPANET. While the early use of the Internet was strictly for academic and research purposes, the use of the Internet for commercial purposes started in the early 1990s with the development of the World Wide Web.
In addition to the continued evolution of the Internet, the twenty-year period that began around 1985 saw the deployment of four distinct generations of enterprise or private WAN technologies. For example, in the mid to late 1980s, it became common for enterprise IT organizations to deploy integrated Time-division multiplexing (TDM)-based WANs to carry both voice and data traffic. In the early 1990s, IT organizations began to deploy Frame Relay-based WANs. In the mid to late 1990s, some IT organizations replaced their Frame Relay-based WANs with WANs based on Asynchronous Transfer Mode (ATM) technology. In the 2000s, many IT organizations replaced their Frame Relay or ATM-based WANs with WANs based on Multiprotocol Label Switching (MPLS). Cost savings were one of the leading, if not the primary, factors that drove the adoption of each of these four generations of WAN technologies.
In the current environment, the two primary WAN services that IT organizations use are the Internet and MPLS. A previous blog entry discussed possible future use of Software-Defined Networking in the WAN, so with SDN as a possible exception, there is no fundamentally new generation of technology focused on the WAN under development today. Relative to the deployment of new WAN services, what sometimes happens in the current environment is that variations are made to existing WAN technologies and services. An example of that phenomenon is Virtual Private LAN Service (VPLS), which combines Ethernet and MPLS. Another example is the deployment of WAN optimization functionality.
At the same time that there is an absence of fundamentally new WAN technology, IT organizations are facing a number of challenges relative to the WAN. This includes the growing volume of WAN traffic, the increasing deployment of delay-sensitive traffic such as video, and the need to support the access of applications and services offered by cloud service providers. In order to respond to these challenges, IT organizations must develop a plan for the evolution of their WAN. Given the absence of new WAN technologies, this plan must focus on the adoption of the few new services that are brought to market, along with the broader adoption of technologies such as WAN optimization. In a future blog, I will discuss how IT organizations ought to plan for their WAN, and factors they should consider in order to improve this important function.