UNITED STATES 
`
`Apps switches boost availability
`By Erik Giesa, special to Network World
`Network World |
`JUL 21, 2003 12:00 AM PST
`
`Layer 7 load balancing devices , also known as Web or application switches, can drill down into URLs or HTTP headers
`to direct requests. An emerging technology, deep packet inspection, allows these switches to gain an even better view
`of content.
`
`Layer 7 load balancing devices, also known as Web or application switches, can drill down into URLs or HTTP
`headers to direct requests. An emerging technology, deep packet inspection, allows these(cid:272)switches(cid:272)to gain an even
`better view of content.
`
`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.
`
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`Non-HTTP-based applications or transactions would benefit from the same horizontal-scaling model. Many
`applications never use HTTP, and others might use HTTP only as the transport, such as Web services. Traditional
`Web or application switches can't do the job because HTTP is the only type of tra(cid:119)ic they can act upon.
`
`To extend the benefits of horizontal scaling to all IP applications, the load-balancing device needs to inspect deeper
`than the URL or HTTP header and into the IP datagram. Now companies can use the same architecture for non-HTTP
`back-o(cid:119)ice applications to provide the same economies of scale and operational e(cid:119)iciencies that traditional load-
`balancing devices have provided.
`
`Deep packet inspection addresses this problem. This technology directs, persists, filters and logs IP-based
`applications and Web services tra(cid:119)ic 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.
`
`Complete view
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`Deep packet inspection lets the application tra(cid:119)ic 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 tra(cid:119)ic management device or load balancer intercepts the data on its way to the final
`destination, reassembles it into its original sequence and bu(cid:119)ers it into memory.
`
`By acting as a partial proxy for specific application data flows, the tra(cid:119)ic 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.
`
`Optimum transit
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`Once the tra(cid:119)ic 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 tra(cid:119)ic 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.
`
`Because deep packet inspection can recognize any element of a packet, it can be used to manage tra(cid:119)ic for any type
`of IP-based application, including enterprise applications such as(cid:272)CRM, databases, mobile and(cid:272)wireless(cid:272)applications,
`and Web services. At a large company, for example, a tra(cid:119)ic manager with deep packet inspection capabilities could
`be used to distinguish between read and write tra(cid:119)ic to database servers. The company could save money by
`purchasing less-expensive servers to handle the read tra(cid:119)ic.
`
`Deep packet inspection provides detailed control of all IP tra(cid:119)ic, letting businesses meet complex(cid:272)security(cid:272)and high-
`availability requirements while gaining operational e(cid:119)iciencies. How it works: Deep packet inspection
`
`SponsoredPost Sponsored by Cisco
`Cisco data center and cloud networking recognitions
`
`Giesa is senior director of product management for F5 Networks. He can be reached e.giesa@f5.com.
`
`Join the Network World communities on Facebook and LinkedIn to comment on topics that are top of mind.
`Copyright © 2003 IDG Communications, Inc.
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