Demand for security appliances is going through the roof, with western European sales of the devices predicted to reach over $1.4bn in 2009, up from around $625m in 2004.

According to a newly released IDC study, the sector is growing at a compound annual growth rate of 18 per cent.

Of the three security appliance categories covered in the study - firewall/VPN, intrusion detection and prevention (ID&P), and unified threat management (UTM) - the latter is expected to exhibit the strongest growth, enjoying a rate of 61 per cent between 2004 and 2009.

"There will be a significant shift in the western European security appliance landscape over the forecast period," said Oliver Harcourt, senior research analyst for European enterprise server solutions at IDC.

"In 2004, firewall/VPN security appliances dominated the market as the primary category, but over the forecast period its share of the market will be cannibalised by ID&P and in particular UTM appliances as they exhibit stronger growth.

"In 2009, UTM security appliances will be the primary category, constituting around 50 per cent of western European security appliance revenue."

IDC's report noted that, over the past few years, appliances have become the preferred form factor for delivering security for vendors, managed service providers, resellers and customers.

Security appliances were originally restricted to firewall/VPN functions, but appliances are now available for practically all security functions, as well as appliances that integrate multiple security functions.

"Security appliances have proved popular and will continue to do so because of the advantages they offer in terms of performance, convenience, cost and choice," said Thomas Raschke, programme manager for European security products and strategies at IDC.

"UTM security appliances, which consolidate multiple security features on a single appliance, will spearhead growth in this market because of the additional benefits they offer, such as reduced complexity and costs, combined protection to combat blended threats, flexibility and scalability."