Before the VPN, ERDAS had plain old dial-up access among its U.S. and U.K. offices. The company initially went with the VPN WAN for its sales and marketing operations worldwide--ERDAS' software and product development applications run only on the corporate LAN in Atlanta. But those users already are asking to join the VPN, which would mean 10-GB satellite imagery files that would make their presence known on the VPN. "We deal with very large files that will have to be transferred after-hours or our real-time sales applications would grind to a halt," Schulte says. "We can turn up the bandwidth because this solution scales. If we see a crunch, we will look at products that prioritize traffic."

The bigger issue with adding that traffic to the VPN, however, is security, given the sensitivity of some of ERDAS' projects. Today, the company encrypts its traffic with private keys, and is considering adding IPsec (IP Security) encryption in the future.

ERDAS uses a DSL access service from Concentric Network and a T1 service from GTE Internetworking. "With two different Tier One providers using two different access technologies, we're covered if either service or technology [DSL or T1] should hiccup," Schulte says. ERDAS' U.K. office uses The Planet, a local ISP there, which connects directly to GTE Internetworking's backbone, he says.

ERDAS' Alexandria, Va., and Englewood, Colo., sites have DSL access to the VPN, but DSL service isn't yet available in San Luis Obispo, Calif., or Leavenworth, Kan., so ERDAS is using ISDN in San Luis Obispo, and an analog router that combines multiple analog lines in Leavenworth. ERDAS "tunnels" its traffic over the Internet backbones with a combination of PPTP and L2TP tunneling protocols. Telecommuters come in over the VPN via PPTP, DSL or cable modems; users on the road, via dial-up.

The downside of this mixed bag of technologies is managing all of it. ERDAS manages its own edge devices, the DSL- and other routers. "Where connectivity options are limited, like in Leavenworth, we make do with what's available," Schulte says. "It's not ideal, but I actually enjoy having virtually every major access technology."

Still, ERDAS wants to simplify its VPN. Once its existing Internet service contracts expire, ERDAS will go with a single network provider for its domestic, international and dial-up Internet services.