Chances are that at one time or another, you've been frustrated by modem connectivity (or lack of it). Troubleshooting connections can be difficult, and it's sometimes hard to find the right tools. Typical client software doesn't tell you much about what happens after modems synchronize. Windows95, the most heavily used dial-up client, often provides erroneous error messages and abysmal connection-analysis information. Recent Windows updates, such as OSR2, Dial-Up Networking 1.2 and the Windows98 client, improve the situation a little. But when you're forced to dig deep into troubleshooting a PPP connection, nothing beats an external analyzer.

To view the Report card.Fortunately, a software-only PPP analyzer isn't going to blow your budget, and it can run on an existing PC. At only $395 each, Klos Technologies' SerialView and Frontline Test Equipment's Serialtest Async are both bargains. Each product uses a pair of serial ports and a custom cable passively connected from another computer's modem and its serial interface--and both perform essentially the same function--capturing and displaying PPP packets. Both get the job done, but each takes a slightly different approach.

We gave Klos' SerialView the edge because it decodes a wider range of protocols with greater detail than Serialtest, and has capture triggers and filters not found in the Frontline product. But this is a close call; there are many functions at which Serialtest excels that SerialView simply doesn't attempt. The ideal product would combine Klos' strengths--protocol decodes, analysis capabilities and a simple interface--with Frontline's strengths--Windows presentation, the ability to run the analyzer on the desktop being examined and control lead examination. To decide what's best in your environment, you'll want to use Network Computing's Interactive Report Card ® and adjust evaluation weighting as you see fit (see www.networkcomputing.com/915/915r2report.html).

Both of these products principally target PPP product developers and experts, offering little help to the novice. Neither provides any high-level interpretation of PPP negotiation, any help specific to PPP or even a tutorial. Fortunately, PPP is a relatively simple protocol with a structure that is easily understood.

Both products adequately capture and display packets at speeds of up to 115,200 bps. Users with higher-speed serial ports, such as those based on 16650 and 16750 UARTs (Universal Asynchronous Receiver/Transmitters), shouldn't expect to examine packets at those faster rates. Neither product can display compressed PPP data or piece together a multiport session that utilizes Multilink PPP, although both functions are technically possible.