ECCI’s QuadRANT Remote Access System

Remote network access has become a necessary component of most corporate networks. As the number of traveling salespeople and telecommuters continues to grow, so do the requirements for remote access systems. Choosing software is easy: A Windows NT Server with Remote Access Service (RAS) can support up to 256 simultaneous users and provides a stable, secure environment for dial-in clients. Choosing hardware is not so simple. Most devices that provide access to multiple modems are available only in four-, eight-, or maybe 16-port versions, and you can quickly outgrow them.

Enter ECCI's QuadRANT remote access system. It includes several options that can take you from a four-port ISA modem adapter to rack-mounted modem pools that will reach and exceed NT's limit of 256. Expandable is an understatement.

Have Some Port
ECCI's entry-level remote access product is the QuadRANT.ecm, a four-port plug-and-play ISA card (at least, as close as NT can get to plug-and-play through proprietary software) with four 28.8Kbits per second (Kbps) data/fax modems. Just install the board (make sure you have a full-length slot available!), and turn on the system. After you log in, you install the software, and the ECCI setup program will search for and allocate an available interrupt and I/O address.

A great feature of the QuadRANT.ecm is its expandability. You can use it as a control board for external modem cabinets to control up to 64 additional modems connected by the COMM bus (a simple 9-pin serial connection). ECCI has two cabinets available, one that holds from four to 24 modems and another that holds four to 64 modems. ECCI's configuration software makes setting up additional modems simple. After using the COMM bus to connect your QuadRANT.ecm and the external cabinet, start the QuadRANT Port Manager. Choose Full Configuration from the Configuration menu, and your new COM ports will be ready to go.

At the high end of ECCI's spectrum is the QuadRANT COMRAK cabinet. The COMRAK is a rack-mountable cabinet that can hold any combination of up to 64 modems or high-speed serial ports. Nearly everything in this cabinet is hot-swappable, including any of the three cooling fans, the three redundant power supplies, and the QuadRANT modems. That's industrial strength.

From Server to Module
You can choose between two methods to connect the COMRAK cabinet to your server: with a differential SCSI controller or a QuadRANT.ecm board as a controller. The COMRAK cabinet is rack-mountable, and because it will probably not be within just a couple of feet of your server, the easiest method is with a differential SCSI controller. This configuration will give you the best performance. We used an NCR-825 PCI card to connect to the ECCI. (Differential SCSI provides a separate ground line for each data line, and high-impedance termination. Because this reduces line noise, you can use much longer cables for connecting peripherals; the tradeoff is that you cannot use this bus for connecting standard SCSI devices.) You can then chain several COMRAK cabinets on the SCSI bus to reach NT Server's RAS limit of 256. The other method, with a QuadRANT.ecm board as a controller, uses the COMM bus to connect the COMRAK. This method requires the additional purchase of the QuadRANT.ecm board, and you cannot add more modems because of the QuadRANT.ecm's limit of 64 additional modems.

When you use SCSI to connect a COMRAK, the interface between the communications devices (either modems or serial ports) is a Control Module (CM). The two types of CMs are the Single Channel Control Module (SCCM) and the Dual Channel Control Module (DCCM). The SCCM can control up to 64 lines. In contrast, with additional external cabinets connected using the COMM bus, the DCCM can control up to 256 lines. The CM provides its own processor so you can offload most of the connection processing from your server. The DCCM we got with the test system had an 80386SX processor.

At the heart of the QuadRANT system are Protocol Line Modules (PLMs). The types of PLMs are the Asynchronous Stackable Quad-Processor adapter (ASQ-P), the Asynchronous Quad adapter (ASQ), and the Modem Asynchronous Networking adapter (MODAN). These modules comprise the system's communications ports.

The ASQ-P adapter provides four high-speed serial ports that can operate at speeds ranging from 50bps to 150Kbps. The ASQ-P sports an AMD29000 RISC processor and can control from four to 24 serial ports. On the ASQ-P adapter are four RJ-45 connectors that use RJ-45 to DB-25 cables to connect to standard serial devices. These adapters are ideal if you have a ready supply of external modems. The ASQ-P adapter is hot-pluggable. If you need to repair or replace one, it doesn't affect the entire COMRAK cabinet. To swap out an adapter, you simply remove the ASQ-P from the cabinet. RAS will show a hardware failure for the four COM ports belonging to that adapter. When you install the new adapter, the ECCI software will reconfigure the ports, and RAS will show the ports as ready to roll.

If you need additional serial ports but don't want the expense of every adapter having its own processor, you can get the ASQ adapter. It is a daughter card that connects to the ASQ-P and uses the ASQ-P's processor and memory. Each ASQ adapter has four RJ-45 ports, and you can chain five daughter cards to an ASQ-P, for a total of 24 serial ports. The disadvantage to chaining the adapters is that if you need to hot-swap, you cannot remove just the inoperable card; you must take the whole batch. If you attach five daughter cards to a processor card, you must remove all 24 ports while you replace the malfunctioning card.

If you don't already have all your modems, you can consider the MODAN. It also provides four ports on the adapter, but it includes four integrated modems. MODAN cards are available with either 14.4Kbps or 28.8Kbps modems. Each MODAN adapter also has an AMD29000 RISC processor on board. Each modem has an RJ-11 connector, a set of indicator lights, and an individual reset switch. And, like the ASQ adapters, the MODAN adapters are hot-pluggable. If a card fails while a user is connected, you just install a new card, and the software will do everything but reconnect the user.

A final available component that I did not get for review is the Coax Interface Line Module. It lets you use coaxial cable to extend the external COMM bus up to 1000 meters. If you need cabinets in several locations but want just one server, you can buy a DCCM control module and use coax to chain additional cabinets.

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