WAN Acceleration - Wide Area Network Optimization Technology and Application Analysis
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| Wide Area Network ( WAN ) bandwidth is expensive, so most users can only have limited WAN bandwidth. On the contrary, the number of applications on the WAN continues to increase, and speed has become the biggest killer of the WAN. Without increasing the WAN bandwidth, can we find a reasonable way to kill the killer of "too slow speed"? WAN optimization technology has taken on the heavy responsibility. What's more valuable is that WAN optimization does not only stay at the level of speed increase, but also improves traffic management, QoS , etc. It seems that it is really time for users to settle down. Strange but hot WAN optimization is not a new concept. When the low bandwidth and high latency of WAN are exposed, WAN optimization should be very useful. However, the concept of WAN optimization is relatively broad, and different people have different understandings. WAN transmission, Web acceleration , and bandwidth management all fall within the scope of optimization. We will focus on WAN transmission because, on the one hand, it is the most concerned, and on the other hand, solving this problem will solve other problems to a certain extent. As F5 's Marketing Channel DirectorKevinAs the gentleman said, generally speaking when we talk about WAN optimization, we are referring more to WAN transmission issues. Although WAN optimization is not new, for most users, the most appropriate words are unfamiliar or little known. "I have heard of WAN optimization. It seems to be similar to network cache and can increase network transmission speed." Meng Hai, who has many years of experience in network construction and management at Cangzhou Power Supply Company in Hebei Province,RiverMr. Wang's statement represents the understanding of WAN optimization by some large domestic users, while most small and medium-sized users are unfamiliar with WAN optimization. "The current obstacle to WAN optimization is that there is too little publicity, and many users do not know that such technology exists." said Vice President of Kuaisha Technology, which focuses on this field.Zhang FuguoThe gentleman hit the nail on the head. Unlike domestic users who are still unfamiliar with WAN optimization, this concept has become very popular in North America and other countries where informatization was developed early. Last year, Merrill Lynch, an American research organization, conducted a survey of CIOs of 100 large enterprises and obtained a ranking of enterprise network construction expenditures. WAN optimization followed network security, three-layer switching, and VoIP , and the first three items are already familiar to everyone. User demand is the director, and it is impossible for manufacturers not to pay enough attention to this demand. Putting aside traditional application acceleration, data compression, dynamic caching, IP traffic management, and QoS , some emerging manufacturers have found a breakthrough point in WAN optimization based on the principle that innovation can get them started. Actona , Peribit , and Riverbed are among them. However, with the potential to rank "fourth", it is impossible not to attract the attention of the "big guys". As a result, Cisco acquired Actona as early as April 2004 ; a year later , Peribit became Juniper 's table meal. General Manager of Riverbed Greater ChinaWang GuoxingMr. also said, “Many companies approached us, but we refused to sell.” Born to solve problems Why is WAN optimization so popular? The reason is that it can indeed solve several key problems that currently exist in WAN. First, the bandwidth problem. The bandwidth of WAN is much worse than that of LAN. For example, the bandwidth of a T1 line is only one thousandth of that of a Gigabit network, and the bandwidth of many frame relay lines is only 256Kbps . In addition, the increase in WAN bandwidth will lead to a significant increase in costs. Secondly, the delay problem. People who have made cross-border IP calls may have this experience. After you finish speaking, it always takes a short time for the other party to hear the echo. This is the best example of delay, which is even more obvious when making a video call. At present, the application of WAN has increased dramatically. In addition to voice and video, the transmission of graphics or image files and the processing of massive data are all practical applications that trouble users. In addition, there is the protocol problem. Some currently used protocols are not designed for WAN (such as TCP protocol), and the protocol efficiency is low and the performance is not ideal. "The distributed nature and high-performance requirements of today's data protection landscape, along with relatively high WAN costs, can result in disappointing application performance or large WAN expenses," said Joe Skorupa , research director at Gartner . "Enterprises with high-capacity network environments, large numbers of users or many different applications need a WAN optimization solution." Zhang Fuguo believes that many users do have a very urgent need for WAN optimization transmission, but they are not familiar with this new sub-industry in the Internet and are forced to use other technologies that require very large investments (such as satellite data transmission). In the long run, WAN optimization technology has a very good cost-effectiveness and can achieve the advantages of high-bandwidth, stable, low-cost and high-speed transmission, and its prospects are bright. | Technology is a clever way to overcome difficulties Data compression, dynamic caching, IP traffic management, and QoS can all solve the problem of WAN transmission acceleration to a certain extent. However, compression only solves the problem of bandwidth resources. For links with very large delays, compression alone cannot completely solve the problem. Therefore, some new technologies have become the leading role. The technologies used by several leading manufacturers, such as Juniper , F5 , and Riverbed, can solve both bandwidth and delay problems. Mr. Wu Ruosong, the manager of emerging technologies in Greater China of Juniper , said that Juniper 's acquisition of Peribit has enabled it to acquire the ideal WAN optimization technology. In Juniper 's WAN optimization technology system, the first is compression technology, including molecular sequence compression and network sequence caching. But these are not enough. Application acceleration is the feature of the solution, including acceleration based on the TCP layer and acceleration based on the application layer. Ke Wen said that F5 uses new technologies to focus on solving application layer problems, among which TDR (transparent data compression) technology can significantly reduce the bandwidth consumption of many applications, and some applications can reduce the amount of transmitted data by 95% . Wang Guoxing said, " The Steelhead series of appliances, combined with Riverbed 's various technologies (such as data compression, TCP optimization, application-level throughput optimization, remote office file management functions, etc.), can provide a complete and powerful WAN optimization solution for many applications. " Among them, Scalable Data Reference ( SDR ) technology can support all TCP applications, including Microsoft Office , Lotus Notes , CAD , ERP , FTP and HTTP , etc. It can ensure that the same data does not need to be transmitted repeatedly on the WAN. Next, I will explain the essence of the technology in the simplest way possible. Data packets are transmitted in the wide area network. The optimization technology is to split the data packets into many "fragments" and assign unique pointers to the "fragments". The pointers are stored in the local device and the destination receiving device respectively. When the same pointer content needs to be transmitted again, only the pointer is transmitted to the destination, and the receiving device extracts the content from the local device according to the pointer. As long as the "fragments" are small enough, the probability of transmitting the same content will be large enough. For the same user, it is often necessary to transmit the same or similar information frequently, and the effect is very obvious. To give a simple example, for PPT files, the content of the logo , header, and footer in all page numbers is the same, and there is no need to retransmit. Moreover, for the PPT that is changed again , only very little content is often changed. In fact, only the changed content needs to be transmitted again. In addition to the aforementioned multinational companies with great reputation in this field, the reporter was delighted to find that there are also domestic companies with good technology in this field, and Kuaisha Technology is one of them. Zhang Fuguo, vice president of the company, said that many technologies have more or less solved the problem of excessive delay, but the problem of high packet loss rate in the wide area network is also very prominent, especially when data is transmitted across ISPs and multinational networks. The transmission packet loss rate often exceeds 30% . The effect of simply optimizing the delay is very limited, and the problem of excessive packet loss rate must be optimized. In response to the problem of excessive transmission packet loss rate, Kuaisha Technology has developed a comprehensive optimization technology for wide area network transmission - Quickfirer high-speed transmission technology, which can not only solve the problem of excessive delay, but also effectively solve the problem of excessive packet loss rate during transmission. In addition to the technologies mentioned above, a more ideal TCP protocol, High Speed TCP ( HS-TCP ), is already being tested. TCP is often criticized because its algorithm for controlling congestion is not very reasonable. HS-TCP can solve this problem. HS-TCP is an upgraded version of TCP , which has a stronger response capability to large congestion windows in high-bandwidth, high-latency network environments. Implementation in minutes What user groups are WAN optimization technologies most suitable for? Wang Guoxing believes that any company that uses WAN connections (especially multinational companies); any enterprise with low bandwidth, high latency, and large data transmission; and any enterprise that wants to conduct server centralization (data centralization) projects are suitable for using WAN optimization technologies. In other words, any user who feels that remote office applications are slow or wants to increase bandwidth can become a beneficiary of WAN optimization. Indeed, as Meng Haijiang said, with the construction of the four-level data network (national, provincial, municipal, and county) in the power industry, the data at the county level will be concentrated at the provincial level in the future, which will require a large amount of data to be transmitted on the wide area network, and such equipment and technology will likely be needed in the future. In fact, this kind of data concentration is similar in many industries. For example, a friend of the reporter in the tax system said that some small and medium-sized business outlets are still connected to the upper-level units using frame relay. If the data volume is larger, it will be a test for the transmission speed. Obviously, wide area network optimization technology has a lot of room for use. The user group suitable for WAN optimization technology is large enough, and the deployment issue deserves attention. Generally speaking, this type of equipment is not complicated, and the most typical one is to "go hand in hand" with the router (the typical deployment method is shown in the figure below). At each remote node, it only needs to be directly connected to the router, and no modification is required for the original network and application. It is transparent to the server and terminal, and there will be no single point of failure. 
It is meaningless for such equipment to exist alone. Generally, it needs to be "appeared in pairs", that is, such equipment should be deployed in all branches that need to speed up. Of course, for users who are skeptical, a good way is to install such equipment in the headquarters and one branch for trial, and then promote it if the effect is satisfactory. Because this type of equipment is very easy to install, such as Juniper 's products, which use a web -based installation wizard, it only takes 10 minutes to complete the deployment and configuration. | Independent existence or integration Since it is more of a companion to the router, what if this type of device appears as a module of the router? Wang Guoxing believes that since there is no unified standard for WAN optimization equipment, there can be different implementation methods. For simple optimization processing (such as compression only), it can be integrated with network equipment and security equipment; for complex processing, since there are great requirements for CPU , memory, and hard disk, it is more reasonable to have it exist separately. Zhang Fuguo believes that it is better for WAN optimization equipment to exist separately. First, separate equipment can be more flexibly configured in the user's existing network environment, and during the equipment integration process, the changes to the user's existing network can be minimized. Secondly, existing separately can also save users unnecessary investment, because most users have already purchased a variety of network equipment and security equipment, and users only need WAN optimization products. At the same time, we have just received news from the market that McData will rebrand Riverbed 's Steelhead dedicated appliances as McData SpectraNet WDS (Wide Area Network Data Services) and use them with its directors to allow remote branch offices to access applications and files located at central sites at LAN speeds. Edit and think Good wine needs no bush You may not receive an email you need urgently, but the other party tells you that it has already been sent; when you make a cross-border IP call, it takes a while for the other party to respond after you finish speaking. Such phenomena are all caused by latency. Latency is the biggest killer of WAN, and increasing the limited bandwidth cannot fundamentally solve the problem. Technical problems are not difficult to overcome. WAN optimization technology is the "magic pill" to solve low bandwidth and high latency. With it, your WAN may achieve performance similar to that of a LAN. However, when I talked about this topic with a friend, he was not optimistic about the development of WAN optimization technology in China. The reason was simple: many large users have enough dedicated line bandwidth, because these users are "not afraid of spending money" and often get "benefits" from purchasing dedicated line bandwidth; small users' applications are not that complicated, and even if there is an application demand, the cost of purchasing such equipment is a major obstacle for these users. The reason why the application demand is very strong abroad is that these users have more complex applications and are very concerned about "input and output". Who can say that this guy's analysis is unreasonable? The market environment tells us that there are more and more branches (statistics show that 67% of employees work outside the headquarters); on the contrary, data centralization is the general trend. In this case, when the application is so complex that "increasing bandwidth several times" still cannot solve the delay problem, and when WAN optimization is as familiar as Layer 3 switching and VoIP , it is natural for many users to choose this technology. Just imagine how wonderful it will be when pointers representing "fragments" exist in large numbers in the WAN. At present, the most important thing is to let the majority of users quickly understand WAN optimization. For the mainstream manufacturers, if they can join hands, expand together, and establish extensive cooperation with the industry, it is believed to be far more important than "emphasizing whose technology is better than whose". The reason is simple. If you don't know and understand, what's the point of talking about technology and application? |
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