Two of the hurdles to clear when setting up Internet-based VPNs are delay and availability, but both can be addressed by getting service-level agreements from service providers.While SLAs guarantee delay will be below a certain point and the network will be available a certain percentage of the time, they are really just agreements about how much the provider will be penalized when the SLA isn't met. Presumably they won't want to pay the penalties, so they will try hard to meet the SLAs.That doesn't really help customers much when the network doesn't perform to the agreed level, so customers turn to having important sites fed by more than one Internet connection, a setup called multihoming. If one ISP fails or suffers major delays, the customer can switch to the other. If both are performing well, they can load balance among all the ISPs.Route control gear can help do this. They measure performance through each ISP and divert traffic to the one that's performing the best. Or the gear can divert based on the least-cost option. Or it can divert based on a mix of performance and costs and other factors, such as time of day.It can be useful to install such tools at each site that's connected to a VPN, but the route control devices can be too expensive to place at every smaller site. Proficient Networks is trying to address this with a $9,000 box that can track the performance of the Internet connection between a given site and 100 other sites. These other sites would include the other company locations that are part of the VPN.This idea isn't new. A competitor in this field, netVmg, makes a $12,000 box that monitors up to 50 destinations. But it is still a useful tool for optimizing performance and costs for Internet access in VPNs that are critical enough to a business to warrant outfitting sites with more than one link to the Internet.