US company Radware has announced a product it hopes will allow companies to make more use of conventional broadband links for applications such as VPNs.

Despite broadband's popularity, many businesses still refuse to rely on it, even as backup for leased lines, because service levels are uncertain.

Linkproof Branch “virtualises” the network, spreading traffic across up to ten links, including leased lines and DSL. It uses all of them, rather than keeping redundant links for failover.

“Organisations with branches need to increase bandwidth to central sites, but they have to do it securely and reliably,” said Radware’s Ken Tan . “So far, they have either gone to a carrier for a private network, based on leased lines or ISDN, or used VPNs over the Ethernet – which is cheap and cheerful, but not reliable. We solve this using multiple ISPs.”

The new box extends Radware’s existing range to smaller offices. It has been designed to sit inside the network in a branch office, setting up virtual tunnels to a similar box at the head office. All traffic sees the same public IP address.

“BGP [the border gateway protocol] could solve the problem,” said Tan, “but it is expensive and designed for ISPs. It has no traffic shaping and no recognition of latency.” By contrast, virtual tunnelling can prioritise applications and set up tunnels for voice traffic, using DiffServ for quality of service.

The product already has users in the UK, and will arrive in Europe before the US. It costs £3,600, or £5,000 with security and quality of service included.

Although other companies such as F5 could share ISP links, they were still too expensive for branch offices, maintained Tan.