Sun has entered the crowded content-switching market with a novel twist: Its Sun Secure Application Switch N2120V lets users define multiple switching and routing domains on a single box.

In our Clear Choice Test of this switch, we found it relatively easy to set up multiple domains. Performance also was good, with support for up to 1.25 million concurrent connections and as many as 230,000 new connections set up each second, making the Sun box a fit for all but the very largest data centers .

N2000 series switches, which Sun picked up with its Nauticus acquisition in 2004, offer many of the same features as competing application acceleration devices from Array, Citrix, Crescendo, F5 Networks, Foundry Networks and Juniper, including load balancing, content switching, TCP multiplexing, SSL acceleration and protection against denial-of-service attacks .

Virtualization is where the N2000 devices differ. The Sun N2120V lets users define multiple switch and router instances (called vswitches and vrouters) on the same hardware, each with unique broadcast domains. One N2120V can be configured with up to 10 instances of virtual switches and routers, each with routing tables that can reuse the same address space. Virtual switches and routers also can span multiple physical devices, with up to 128 interfaces per vrouter.

Virtualization is useful for companies looking to partition routing information between different divisions, locations or customers. This feature also lets network managers define different domains, or tiers, based on application type.

A vswitch sitting in the access tier of the Sun box provides clients with a single virtual IP address, behind which there might be dozens or hundreds of servers, often using private addresses that require network address translation. A load balancer in the Web tier parcels out client requests to Web servers. Often embedded in these Web requests are calls to back-end databases or other applications in the application tier. A content vswitch with application awareness parses these calls and sends them to servers in the application tier.

While many vendors' application front-end devices can handle this three-tier design, Sun's device allows multiple instances of each tier to be defined on the same switch. For example, two sets of application tiers might be set up, one apiece for database and streaming media servers. With competing products, a separate physical device is needed for each tier to avoid overlapping address space.