The days of the proprietary client are waning fast, as more and more enterprise applications become Web-enabled or entirely Web-based. Critical applications from e-mail to CRM to custom internal apps are all running on either internal or external Web sites, and they need both quick response times and fault tolerance.

The Bottom Line Juniper DX3680 v. 5.2 Juniper Networks, junipernetworks.com Excellent  8.7 criteria score weight Management 9 25% Performance 9 25% Ease-of-use 8 20% Features 9 20% Value 8 10% Cost: Pricing starts at $49,995; price as tested is $70,485 and includes upgrade licenses for HTTP Acceleration ($12,995) and to enable Overdrive AppRules and HTTP Caching ($7,495) Bottom Line: The DX3680 is an example of the adage "you get what you pay for." It's a very capable 2U appliance that not only creates clusters of Web servers but also adds SSL encryption, user authentication, and protection against hacker attacks. All of this is done transparently without having to rewrite HTML code on the Web servers. The application rules functionality provides powerful customization capabilities as well. About our Reviews and Scoring Methodology

[ The Juniper DX3680 received an InfoWorld Technology of the Year award. See the slideshow of all winners in the networking category. ]

That's where load balancers come in. Adding redundancy and scalability to Web applications, load balancers create a cluster of Web servers, over which they distribute incoming requests, sending new requests to the server with the least load at any given moment. If a Web server goes offline, the other servers in the cluster take up the slack. Geographic load balancers create clusters at different physical locations so that applications will still be available even if an entire datacenter loses connectivity.

The Juniper DX3680 goes well beyond the relatively simple task of creating clusters of Web servers – it can accelerate Web applications with several methods, including by compressing the HTTP sent between the Web server and the client, caching static parts of the Web page, and offloading SSL processing from the Web server. It will also optimize the network traffic so that the viewing of a Web page, which might normally take 100 back-and-forth messages between the Web server and client, can be accomplished with only a few messages.

In addition, the DX3680 shields applications running on Web servers from Internet-based attacks, preventing hackers from issuing unauthorized commands or taking advantage of known bugs in the Web server software, and it can handle user authentication via RADIUS or LDAP.

Cluster call

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Juniper

Bucking the trend of cramming load balancers with switches and as many as 20 Ethernet ports, Juniper decks out the DX3680 with a total of 4 ports, which should be enough in most cases – one in and one out is all a load balancer really needs. Initial setup of the system is straightforward, via serial terminal, though it’d be nice to see a default IP address allowing for initial configuration via browser.

Once the basic networking information is set, you can begin creating virtual clusters, as well as rules for how each cluster will be used. There are three types of clusters: a basic cluster, a forwarder, or a redirector.

A basic cluster defaults to high security and allows only basic HTTP functions – anything more has to be explicitly allowed through a rule. The DX3680 has predefined rules for a number of standard Web applications, including Microsoft Outlook Web Access (OWA) and SharePoint, PeopleSoft, and IBM/Lotus Domino. Most of the rules have to be applied at the command line rather than through the Web GUI. If you want to create your own rules, there are examples to work with, but it's not a simple process – be prepared to test and debug your new rules. This is equally true with similar load balancer products, such as F5’s application rules.

For non-HTTP traffic, a forwarder simply passes all traffic to the server cluster without processing it or accelerating the outgoing traffic. A redirector takes traffic addressed to a given address and sends it to a different one, without processing it at all.