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The 540 amalgamates traditional server load balancing with application performance optimisation and rounds it off with Barracuda's optional application security.

Features include Layer 4/7 server load balancing, content switching, SSL offloading, HTTP caching and compression. It performs SSL acceleration up to 6,000 TPS and can handle up to 100 real servers out of the box.

On review we have the 1U hardware appliance but Barracuda also offer this ADC as a virtualised version. The hardware appliance has four Gigabit ports and supports a maximum L4 traffic throughput of 2Gbits/sec. The 540 offers a range of deployment choices and for testing we used the two-arm mode which kept our physical and virtual servers on different subnets. The 540 also supports high availability clusters where two appliances run in active/passive mode.

Installation in the lab was simple as we started with a local monitor and keyboard to enable management and Internet access. We liked the fact that the appliance has a dedicated WAN port at the rear for management access and firmware upgrades, thus leaving the four data ports free.

The 540 adheres to the common concept for server load balancing where you create farms using multiple physical servers and assign these to virtual services. The main web interface is easy to use and we had no problems creating multiple virtual services and assigning physical servers to them.

For load balancing you have weighted round robin and weighted least request modes, while adaptive scheduling allows the 540 to modify server priorities on the fly and tailor them to suit performance. It can use SNMP data on CPU usage, poll a URL on each server to get a response time and for Terminal Servers, monitor the number of connections per server.

The 540 supports a wide range of L4 and L7 connection persistence methods and a key feature is its ability to apply a web firewall security policy to each virtual service. It comes with predefined policies for apps such as OWA, SharePoint and Oracle, but you can easily create your own as required.

Policies can set request limits to block buffer overflow and DDoS attacks, implement transparent cookie encryption and use URL protection to block malicious scripts embedded in URL requests. Cloaking protects sensitive information about your real servers by masking HTTP headers and return codes, while data theft protection can be used to overwrite sensitive information such as credit card details where only the trailing numbers are visible.

Security gets even better with the latest v5.1 firmware as, along with support for VMware View, it allows you to integrate tighter external authentication. Supporting LDAP, RADIUS and Kerberos, the appliance compares a user's web login page with the authentication server and permits or denies access to the web application as required.

To test Barracuda's claimed maximum throughput, we hooked the 540 up to the lab's Ixia XM2 chassis equipped with two Xcellon-Ultra NP load modules. We created an IxLoad Layer 4 test with two HTTP client/server streams, each using dedicated virtual servers with two real servers behind each one.

We configured a load objective of 1Gbits/sec for each stream and used a web page size of 512KB. Within a few seconds of starting the test, IxLoad showed a rock steady 1.9Gbits/sec confirming Barracuda's quoted figures. The Load Balancer ADC 540 delivers the features that mid-range businesses demand and at a price they can afford. It's easy to deploy, provides valuable application security measures and is clearly capable of handling high web traffic volumes. NC

Product: Load Balancer ADC 540
Supplier: Barracuda Networks
Tel: 01256 300 100
Web site: www.barracuda.com
Price: From £8,797 excluding VAT