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WAN Optimization
WAN Optimization technologies address optimisation solution which turns out WAN experience into LAN. By optimising data layer, transport layer and application layer, provides customer whole new wide area network experience: avoid redundant data transmitting; adopt more stable, faster transmission protocol; improve application system work efficiency. Apart from this, WAN Optimization technologies offer whole new wide area network construction solutions to IT manager by reducing huge investment to lease lines, avoiding large scale network infrastructure implementation to help enterprises achieving the green IT.

SANGFOR Technologies adopted following technologies to help you achieving WAN Optimization
TCP Proxy
By deploying SANGFOR WAN Optimization appliance at each end through the wide area network, in the process of TCP connection, WAN Optimization appliance ‘monitoring’ the message of ‘ACK’ in traditional TCP handshake process and capture it. It turns the originally one segment TCP connection between client and server out into three segments of TCP connections. WAN Optimization appliance at client end acts as a server at client end while at the same time the other WAN Optimization appliance at server end acts as a client at server end, by means of this, the former three times TCP handshakes through wide area network turns out to be finished in local area network, highly improved TCP connection succeed ratio.

TCP Proxy cuts delay overlying during TCP transmission which is caused by RTT with the method of local response; it is suitable for high delay environment. Especially during the first time transmission, user will experienced an obvious speed up. TCP proxy supports much more towards Application Proxy. Although WAN Optimization does not support Application Proxy to some of the applications, but due to the effect of TCP Proxy, WAN Optimization still can improve the performance of these applications.
Byte cache
SANGFOR originally designed ‘byte cache’ is able to cut redundant data at maximum extent during data transferring to improve bandwidth quality.

When data pass through WAN Optimization appliance, it will be cut into data segments at 100-200B at the same time be allocated with a unique label (10B) to send to the peer end WAN Optimization appliance(storage data bases at both end of the WAN Optimization device are precisely matched ). In following transferring process, any data or file will be cut into data segments by WAN Optimization appliance and matched one by one with the current data segments. If match successfully, only the corresponding labels will be transferred the peer end WAN Optimization appliance and at the same time restore the labels into data segments. If match unsuccessful, both the data segment and label will be sent to the peer end WAN Optimization appliance to ensure the equality at each end of WAN Optimization appliance.

WAN Optimization appliance designates each segment a unique label, this label not only include corresponding data information but partial information of the neighbour data packet, in this caste, when a data packet loses, WAN Optimization appliance will restore the lost packet according to the label of neighbour data packet without re-transferring to improve transmission efficiency.

Byte cache has an ability to reduce data amount during transmission, such as: origin file is 10M at both sending end and receiving end, data amount may probably reduce to 100K after optimisation procedure by WAN Optimization appliance. It means user has extend his bandwidth logically by using WAN Optimization appliance while the actual bandwidth remains the same, but simultaneously the data amount has reduced to 1/10 even 1/100 compares to the original size which leads to the conclusion that the logical bandwidth has expand by 10-100 times. Not all the data can be optimised by byte cache in real network environment; data which can be optimised gets different effect as well. But user will experience bigger bandwidth throughput and much higher speed.

Due to special properties of certain protocols, server need to judge source address of data packet, if source address in received packet header different from source address encapsulated, the server will reject the corresponding request from this data packet. In this caste, we need WANO-S to restore source address into IP address ( at client end. When data packet arrives at WANO-S, destination address will be restored to the original server address ( but source address restore into original client end address ( is optional. The benefit is: when it happens to unsymmetrical route, shut SNAT down, no matter data packet choose line A or line B, to server it’s WANO who forwarded it to server, in this caste we avoid the influence that unsymmetrical might cause.

Only if the data packets pass the DNAT process, it will be conducted to acceleration module of WANO-C by data packet detecting module in WANO-C, it will transmit through acceleration tunnel between two WANO appliances.

GZIP compresses static files such as HTML, JavaScript, CSS and dynamic files as asp, aspx, php, jsp, etc. The biggest advantage of this compression algorithm is to speed up the access speed of browser at client end by reducing the data flow transmitted.
LZO is a compression algorithm which dedicated on speeding up decompression. It’s short for Lempel-Ziv-Oberhumer with following benefits: easy decompressing with high speed; no memory is needed; high speed compression; 64KB memory is needed during compression; adaptable of increasing compression rate in the cost of reducing compression speed while maintaining the decompression speed; generate compression level beforehand to secure a competitive compression ratio; another 8KB memory compression level is also available; the algorithm is thread-safe; the algorithm is lossless.

LZO compresses data block into matched data (sliding dictionary) and unmatched literal serials. LZO treats long matched data and long unmatched literal serials in a bespoke technology which has a distinctive effect on these kind of high redundant data and fair effect on incompressible data, LZO expands the input data block by 16 bytes per 1024 bytes in caste of processing the incompressible data to ensure the effect.

Web Push
Web Push is a specialized acceleration technology by pre-fetching the web objects in the branch end so that they can be fetched locally when client end needs to fetch these certain objects to speed up the http web accessing.

Dynamic IP addressing

Dynamic IP addressing
When dynamic IP address at both end of VPN tunnel, traditional method will not work because of both ends cannot secure the IP address of each other. By using this technology, WAN Optimization devices will find the IP address at each other end dynamically and then set up VPN tunnel.
Set up multiplex VPN tunnel with multiplex bandwidth and failover, for example: there are two internet lines at each end of the VPN device that established the tunnel, thus this tunnel can generate 2*2=4 VPN tunnels and guarantee the reliability and stability of VPN by certain algorithm.
Tunnel self-recovery
When VPN tunnel disconnected due to outages, the system will automatically discover the fail and reorganized the new VPN tunnel before network connection recovered to ensure the fluency of VPN tunnel.
Quality of Service (QoS) is a technology solution that overcomes the limitations of standard routing and enables you to tailor traffic routing according to your requirements. SANGFOR QoS provides the following benefits:

Bandwidth guarantee: guarantee mission-critical applications minimum bandwidth which will support them, even in the event of encountering application like P2P, the bandwidth will remain at a certain level. If mission-critical applications were not in use or we didn’t guarantee the 100% occupation of the bandwidth, the rest bandwidth will be grabbed fairly by other applications, is this caste not only we guarantee the bandwidth requirement of mission-critical applications, but improve the whole bandwidth utilization ratio as well.
Bandwidth restraint: restrain non-mission-critical applications to spare more bandwidth to ensure the quality of mission-critical applications.

Priority setting: due to different application critical level, we set different priorities, when bandwidth congestion happens, the priorities valid. Bandwidth meets the application with the highest priority, same with the rest.

Bandwidth reservation: we reserve fixed bandwidth for certain special application and special IP, no matter reserved bandwidth in use or not, the other applications and IP cannot grab it.