Penn State University Broadens On-Campus Internet Access

Patton Short Range Modems to Facilitate SLIP/PPP Links
Judging from the proliferation of seminars and articles on the topic (not to mention E-mail addresses on business forms), one might think that the "Internet" is the hot new business computing tool of the 1990s. But in academia, where the Internet had its beginnings in the 1970s and 1980s, the Net is old news. In fact, use of the Internet is so common that on some college campuses, students pick up a user ID at the same time they purchase textbooks. At Penn State University's main campus--located in University Park, Pennsylvania--the Computer and Information Systems (CIS) Department is constantly cooking up ways to improve delivery of Internet services to students, faculty and administration. This is no small feat. Penn State's CIS Department is the computing hub for 22 campuses and over 38,000 users across the state of Pennsylvania. On the main campus alone, the CIS Office of Telecommunications (OTC) supports over 100 LANs--and provides custom maintenance on over 30 of those--all connected to routers over an FDDI backbone. Platforms range from PC Clones and Macs, to Suns and RS/6000s, to DEC VAXs, IBM Mainframes and Cray Supercomputers. Just about everyone on campus expects a connection to PREPNET, Penn State's primary Internet provider. Via PREPNET, users can travel throughout the Net, conferencing with thousands of other users and exchanging vital information.

Mushrooming Demand
The normal method for a user to hop onto the Net at Penn State is via LAN connection. Just by virtue of being an Ethernet node, a user's PC, terminal or workstation can tap into a full range of networked Internet resources: Telnet, FTP, WWW (Mosaic), NetNews and others. However, OTC ran into a problem: Not all campus have a LAN connection. Many are in remote locations on campus and have only a stand-alone PC or Macintosh to work with. Furthermore, some are nowhere near a piece of LAN hardware. According to OTC Systems Engineer John Balogh, about 5% of the potential Internet users on campus fall into this category. Finding a way to get these users plugged into the full range of available Internet resources has been a challenge. As Balogh recalls, Mushroom Research comes to mind. "It's a hole in the ground, literally. There's a garage door into this [dirt] bank, and as you open this garage door and walk in, there's rows and rows of manure with mushrooms growing in it. And there's one desk, one light bulb, and one person, and they need a connection to the Internet. They're not going to pull fiber in there for that one person, at $90 a foot for digging the trench, pouring the concrete and pulling the fiber."

RS-232 to the Rescue?
Since the cost of connection to the FDDI backbone could easily bankrupt some small department budgets, another way to tap into the Net had to be found. The answer seemed to lie in a point-to-point RS-232 connection. Every desk on campus can have access to twisted pair wires, which could theoretically be used to connect a computer to an RS-232 Internet terminal server running either the SLIP or the PPP protocol. This theory sent Balogh on a search for a high speed line driver incorporating SLIP/PPP compatible flow control. He knew the old 9600 baud modems and line drivers currently in use on campus wouldn't evoke cheers from users doing editing or chat sessions interactively on the Internet. "When you type that character," says Balogh,"you want it to go to the other end now." According to Balogh, slow data rates are not the only problem with standard modems and line drivers running SLIP/PP; their flow control methods are also inadequate. Standard modem buffering causes too big a delay for the real-time interaction that's commonplace on the Net. In-band flow control is not recognized by SLIP/PPP. And improperly designed out-of-band flow control causes unacceptable loss of data in both directions. Balogh sums it up this way, "9600 baud, with a big buffer on it and in-band flow control is just like 'three strikes and you're out.'"

Patton Makes the Connection
When Balogh put the word out that he needed a high speed (38.4Kbps and above) RS-232 short haul with very specific flow control characteristics, only three vendors agreed to attempt a product development. Of those three, one vendor developed a product that could transmit data quickly enough, but provided out-of-band flow control that was too slow. Another vendor promised a satisfactory product, but had to send prototypes to a laboratory outside of the US for fine tuning. The turn-around times proved too long and they were eliminated. Finally, Patton emerged with a unique short range modem: the Model 1018. Not only does the Model 1018 support data rates to 57.6 Kbps, it passes two sets of flow control signals in a manner compatible with the SLIP/PPP protocol. The key to the success of the Model 1018 is its ability to multiplex RTS/CTS in with the data. This allows hardware with SLIP/PPP drivers to "see" RTS/CTS as out-of-band, while the short hauls actually pass the signals in-band between each other. DTR/DCD handshaking is also performed by the Model 1018 in its second out-of-band channel. The result? The RS-232 Internet user gets a "real time" interactive feel and no data is lost due to sluggish handshaking. What's more, this is accomplished without the use of buffering. As Balogh puts it, "...with small buffers (or no buffers) and out-of-band flow control, you have faster turn-around when you're typing. Any delays would kill the performance of interactive protocols like X-Windows. It seems more like you're right on the wire, which is what we're trying to provide to the user."

The Net Result
Penn State's planned installation of Patton Model 1018 short range modems will initially provide point-to-point RS-232 Internet connections for about 400 users on the University Park campus. Similar connections may be added across the Penn State University system in the future. The figure above shows the topology of the connection between each "non-LAN" user and the Internet. The OTC Department expects several benefits from the implementation of this high speed RS-232/terminal server topology:

• The ability for non-LAN users to access networked Internet resources .
• A more responsive feel for non-LAN users while typing interactively on the Net.
• Significantly reduced cost to campus departments for the addition of a user to the Net (an RS-232 connection costs departments about 6% of what an Ethernet connection costs on a monthly basis).
• Reduced support overhead due to standardization of the RS-232 topology campus-wide.

With all the above benefits, is John Balogh ready to scrap thousands of 10 Mbps Ethernet nodes in favor of RS-232? Not hardly. He cautions, "We're not encouraging this as a replacement for Ethernet because it's much slower. It's not the optimal solution. But for those people who don't have much of an option, it's a Godsend." To that we can only say, "amen".