Transmission Control Protocol (TCP) application of the limitations affecting the delivery
TCP protocol will be broken down into numerous small data packets to send, and then wait until you receive the packet has been received confirmation message before sending the next packet. If a packet did not arrive, TCP protocol or re-sent, or we believe that the network overload, then load a more aggressive congestion control strategy, slowing down data transfer rate to avoid the trigger down the network.
TCP / IP protocol packet retransmission mechanism to create such a large waste of network resources, significantly reducing network performance. At the same time TCP in order to adapt to different WAN environments with a complete transmission throttle characteristic, in a time when packet loss occurs, TCP automatically each time the amount of data reduced by 50%, ie 50% reduction in available bandwidth, when the protocol throttling mechanism for throttling the application packets, application performance would significantly be affected.
The network throughput will be affected by the agreement to cut expenditure outcomes. TCP data transfer is started, it will search for available network throughput, and gradually increase the throughput of successfully transmitted before, so causing slower growth in network throughput, packet loss with fast decay. We call it "TCP slow start" occurs when the network congestion situation, the network transmission performance very slow recovery, network latency increases, the application system and therefore reduce the network performance.
For example, in a bandwidth of 100 megabits per second interconnection on the transmission of data across the United States, there will be 100 milliseconds latency and packet loss rate of 1%. This will cause the actual transfer rate is only 10 megabytes per second or less.
As the delay increases, T3 lines capable of handling more quickly down to with the T1 line is almost the same level. In the delay than or equal to 40ms and the TCP window is relatively small, T3 line data transmission capacity is not better than the T1 lines.
When the realization of applications and data centralization centralized deployment, the WAN's physical limitations to application delivery challenges.
The WAN optimization to accelerate the integration solutions to ensure the application of rapid delivery
Gartner research director Joe Alpha said: "Now the decentralized system of data protection features and high performance requirements, and the relatively high cost of wide-area network, resulting in a disappointing application performance or spending large amounts of wide-area network. With high-capacity enterprise network environments with large user or a variety of different applications, they need a WAN optimization solution. "
WAN optimization technology in foreign countries to accelerate the development of nearly 10 years of history, technology is already very mature, and as early as 2006, the U.S. research firm Merrill Lynch on the adoption of the 100 large enterprises CIO survey, obtained the construction of enterprise networks expenditure ranking, followed by WAN optimization network safe the three-tier switching, VoIP, after the previous three we have already too familiar.
Integrated application delivery solutions will become the basic functions, through traffic management, helping customers with smart dynamic bandwidth allocation, behavior-based recognition technology to P2P to restrict management, QOS policy priority to ensure that critical applications and key users of bandwidth. Through the TCP protocol optimization, transparent compression and caching technology to reduce WAN latency packet loss, as well as redundant data transmission, while actively seeking innovative techniques and algorithms to the congestion and make more accurate control. |
