Comtrol Interchange VS 100: RAS in a Stack

We’ve looked at several remote access server solutions over the years in SCO World, but Comtrol’s Interchange VS 1000 and 1100 are one of the easiest solutions to implement. The Interchange VS 1000 provides for virtual remote access as well as true remote access. A virtual RAS connection is really just a standard network cable to a workstation of any type. In this mode, the Interchange VS 1000 is a fancy multiport box.

The Interchange VS 1000 is a squat black box that can be rack mounted or stacked with other networking equipment. The front panel is blank except for a power indicator. The back of the Interchange VS 1000 has a plethora of ports. There are sixteen RJ45 connectors which can take either standard RJ45 networking plugs or RJ11 telephone cables. There’s both AUI and 10-BaseT jacks for connecting the Interchange VS 1000 to a network, a remote serial cable to connect directly to a server for configuration, and a power switch with fan. A spare connector is for an Interchange VS 1100, which offers expansion slots without all the network connectors. Up to three Interchange VS 1100s can be chained from the Interchange VS 1000, so a total of 64 ports are available from an Interchange VS stack.

The Interchange VS 1000 works with practically any operating system, but the configuration and administration routines are Windows NT and NetWare based. We managed to run the configuration application under WABI from a SCO box, although Windows NT is preferable. The Interchange VS 1000 implements dial-back capabilities, PPP and SLIP, as well as CHAP and PAP authentication schemes. We tested the Interchange VS 1000 on a TCP/IP network, but it also runs under IPX/SPX, NetBEUI and AppleTalk.

Installing the Interchange VS 1000 was simple. We ran a Fast Ethernet connection from our hub to the Interchange VS 1000 (standard Ethernet works, too). The VS-Link software was loaded on a Windows NT server through the Network applet. No reboot is necessary after configuring, which is excellent for high-availability systems. The Interchange VS 1000 appears to Windows NT as another network adapter. Setting up the number of ports, Windows NT assigns COM port designations to each connection (it’s kinda neat to have a COM14!). A reboot, plug in a bunch of modems and terminals, and the Interchange VS 1000 is running. We used the Interchange VS 1000 through the hub to connect to our SCO server, as well as the Windows NT server. Both worked just fine.

Interchange VS 1000 supports port speeds to 230kbps on all ports. We didn’t have enough devices that are capable of running that fast to test these claims, but with four ISDN modems (bonded to 128kbps each) and a simulated load of eight workstations (at 128kbps each) the Interchange VS 1000 had no trouble. We don’t doubt it can run as claimed. There is no drain on the servers except for the expected session load.

The Comtrol Interchange VS 1000 worked flawlessly and replaced a much larger (and hotter) RAS chassis we had been using. The elegant design of the system, as well as the smooth configuration application will make the Interchange VS 1000 a winner with system administrators. While not inexpensive, on a per-port basis the Interchange VS 1000 is lower-priced than many single-chassis RAS servers. If you need a bunch of modem or virtual RAS ports, as well as the ability to easily expand to 64 ports, look at the Interchange VS 1000. If only they had SCO drivers!