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1. Computing and Enabling Technologies > Wide Area Network Acceleration and Opt...

Wide Area Network Acceleration and Optimization

Wide Area Network Acceleration and Optimization Lower-cost Wide Area Network (WAN) services and data lines have made it affordable for midsize and some small organizations to link domestic and international offices with headquarters via high-speed data links. (See Chapter 4, “Carrier Networks,” for information on carrier network services.) Previously, these organizations only had access to centralized e-mail. More recently, organizations have centralized an increasing number of IT functions at their headquarters to reduce or eliminate staffing expenses at remote offices. However, when the ability to access applications and files over the WAN is added, linking their remote offices to their headquarters, they often find that users have to sit and wait while files are downloaded. This becomes a critical issue as organizations grow, centralize IT services, merge with other companies, or add remote sites to their networks. It’s not unusual for enterprises to connect their headquarters with as many as 80 remote sites, including branch offices, small sales offices, and warehouses located in their home country, as well as in international locations. WAN acceleration and optimization, also referred to as application acceleration, improves the performance of data lines between enterprise locations. It is done by a combination of improved compression and the elimination of delays caused by the most commonly used protocols. Even with high-speed connections, delays can occur when users access data remotely. Certain protocols are at the root cause for many of the long waits for requested documents and applications to download to personal computers. Downloading delays are referred to as latency. TCP, HTTP, and HTML are the most commonly used protocols that contain many error control messages that cause latency. (See the Glossary for definitions of HTTP, HTML, and TCP.) A number of companies, including Cisco Systems, Riverbed Technology, and software start-up Certeon Inc., offer WAN optimization and acceleration. Gareth Taube, former vice president of Worldwide Marketing at Certeon Inc., refers to the aforementioned protocols as being “chatty”. Examples of “chatty” messages in protocols include “are you ready?” and “did you get those packets?” Error messaging dialogues create delays because documents aren’t downloaded until both ends of the transmission respond to these and other control messages. Certeon’s software improves transmissions by substituting a proxy that emulates these error messages at the receiving end. The sending end removes most of the error messages. At the receiving end, the proxy performs the error control locally so that transmissions are not delayed by control messages. This technique works effectively on high-quality links such as those made up of fiber-optic cabling. Because most WAN traffic is identical to previous transactions, Certeon’s patent-pending de-duplication (a type of compression) sends only changes in data exchanges, not the entire file each time. As an example, when two offices collaborate on a Microsoft PowerPoint presentation, the software learns what is in the file the first time it is sent. When a person resends the file with edits, only the changes are transmitted, thus decreasing the file size from perhaps 5 megabytes to 10 kilobytes. The software at the receiving end reassembles the file with the changes included. In addition to latency elimination and compression, some WAN optimization software can prioritize certain types of data traffic. For example, for a financial institution, it can give priority to customer web transactions over internal communications. This speeds up money transfers to the institution. Streamlining protocols and using compression increases throughput on enterprise data links and creates more capacity for current and future applications. An important capability makes it possible to utilize an organization’s data links to electronically back up corporate data to other sites. If the main data center is destroyed by fire or a natural disaster, the organization’s data is preserved. This is possible because WAN acceleration software and compression technology free up bandwidth capacity for data backup. WAN acceleration software is often installed on standard computers at the customer’s locations. Certeon’s software is downloaded onto virtual servers (servers that can run multiple operating systems and applications), in data centers, and at remote locations. (See the section “Single Servers Functioning As Multiple Servers via Virtualization,” later in this chapter, for information on virtualization.) Additionally, the software can be downloaded to a desktop computer for remote employees. Figure 1-5 portrays an example of WAN acceleration and optimization software installed at headquarters and branch offices. Figure 1-5 Certeon aCelera Virtual Appliance software loaded onto a virtual computer on a physical server at headquarters and at remote branches. Proprietary hardware is not required. (Courtesy Certeon)

  

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