Deep packet inspection
An extension of application-switch technology that lets non-HTTP applications take advantage of the failover abilities of those switches.
Web switches act as proxies for Web applications and servers sitting behind them. Users can virtualize an unlimited number of back-end Web applications and servers, providing better availability, scaling and performance. If an application or switch goes down, the switch directs client sessions to fail over to other available applications and servers without interrupting the client.
Deep packet inspection directs, persists, filters and logs IP-based applications and Web services traffic based on content encapsulated in a packet's header or payload, regardless of the protocol or application type. With deep packet inspection in place through a single intelligent network device, companies can boost performance without buying expensive servers or additional security products.
Deep packet inspection lets the application traffic management device delve into the content of a TCP or User Datagram Protocol (UDP) flow for a complete view. This is accomplished by reassembling IP datagrams, TCP datastreams and UDP packets as they flow through the device to view the entire application content and then act on it according to a company's defined policies.
Through standard TCP/IP networking, messages are broken down into small packets so they can quickly traverse the network. The application traffic management device or load balancer intercepts the data on its way to the final destination, reassembles it into its original sequence and buffers it into memory.
By acting as a partial proxy for specific application data flows, the traffic management device continues to build the message so that more content can be seen, while searching for defined variables on which to act. Users configure these variables in a rules or policy engine that enforces those polices based on the application type, its source or its final destination.
Once the traffic management device locates the information in the payload, it sends the data to the application or resource that can best process the client's request. The application traffic management device then can virtualize or horizontally scale any IP-based application. Deep packet inspection also can be used to inspect transactions for correct application or service variables. If these variables aren't present, the request is discarded, the event is logged and an alert is sent to an administrator.
Additional resources
Web switch vendors evolve
A look at changes in the Web-acceleration market. Network World, 06/21/03.
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