IP application accelerators optimize blocks of data traversing the WAN by maintaining acknowledgements of the data buffers and only sending the buffers that did not make it, and not the whole frame. This allows for the use of a better transport protocol that will not retract data or move into a slow start mode. Using a more efficient transport protocol has lower overhead and streams the data on reads and writes cycles from source to destination. This is completely transparent to the process running a given server application.

Caching

Web documents retrieved may be stored (cached) for a time so that they can be conveniently accessed if further requests are made for them. There is no need for the entire data to move cross the network and only updating requests are sent across, thereby optimizing network bandwidth.

Server load Balancing

Server load balancers distribute processing and communications activity evenly across a computer network so that no single device is overwhelmed. Load balancing is especially important for networks where it is difficult to predict the number of requests that will be issued to a server. Busy Web sites/Web sites with a heavy traffic typically employ two or more Web servers in a load-balancing scheme.

SSL acceleration

Secure sockets layer (SSL) is a popular method for encrypting data that is transferred over the Internet. SSL acceleration is a method of offloading the processor-intensive public key encryption algorithms involved in SSL transactions to a hardware accelerator. Typically, this is a separate card in an appliance that contains a co-processor able to handle most of the SSL processing.

Despite the fact that it uses faster symmetric encryption for confidentiality, SSL still causes a performance slowdown. That is because there is more to SSL than the data encryption. The “handshake” process, whereby the server (and sometimes the client) is authenticated, uses digital certificates based on asymmetric or public key encryption technology. Public key encryption is very secure, but also very processor-intensive and thus has a significant

negative impact on performance. The method used to address the SSL performance problem is the hardware accelerator. By using an intelligent card that plugs into a PCI slot or SCSI port to do the SSL processing, it relieves the load on the Web server’s main processor.