Like Serialtest Async, SerialView ships with a custom cable set that uses two serial ports on the analyzer to examine DCE (data communications equipment) and DTE (data terminal equipment) data streams. In our tests, we also used Klos' ISDNView software, which incorporates ORION Development Corp.'s ByteGrabber to sniff packets on an ISDN BRI link itself. This setup will set you back a couple thousand dollars more than a software-only product, but it reveals much more about both the ISDN connection and the PPP session.

For many ISDN routers, this is the only way to effectively troubleshoot PPP problems. Analyzing at this interface also reveals PPP details that you can't find on the RS-232 side, such as the PPP Identification strings that identify the make and model of the equipment on either side of the link.

A Use for That Old 486

Before loading the main analyzer application, SerialView loads a TSR packet-driver stub for PPP or SLIP (Serial Line Internet Protocol), which provides the analyzer with a generic packet-driver interface. SerialView likes to run on a machine with lots of expanded memory, and it's not a good idea to run the application in a DOS window under Windows95 or from an NT command prompt, especially if you'll be running at high data rates. You should dedicate the machine to running SerialView during analysis.

SerialView's interface is trivial, principally using function keys for navigation. You won't need more than a few minutes to get the hang of the product. It offers two data views: Line mode displays a list of packets with a single-line summary for each, and detail mode displays details within a single packet. The Enter key toggles between them. If you understand that, you understand 90 percent of the SerialView interface.

Within both views, data can be displayed as PPP packets or in raw mode, simply showing hex and ASCII representations. Super-raw mode displays all frame bytes, including MAC (Media Access Control) headers. Messages that are not properly represented as PPP packets are displayed in ASCII format. Happily, this makes AT command dialogues instantly readable in line mode.

Overall, SerialView lacks the interface polish of Serialtest's Windows95-based display. While we expect to see a Windows version of SerialView later this year, the DOS version is missing crucial elements for nonexpert users.And, there's no online help beyond navigation-key details. But for simply getting the job done, SerialView sets the standard by which PPP analyzers should be measured.

Frontline Test Equipment Serialtest Async 1.11 and Serialtest Spy 1.11
Serialtest Async is a work in progress, and it is going to give Klos SerialView a run for the money. While Serialtest's protocol decodes, capture filters and trigger capabilities fell short of those in the Klos product, these gaps likely will close over time. When that happens, Serialtest may be the product of choice for PC-based PPP analysis.

Serialtest has many unique capabilities. Spy mode allows the PC running the dial-up application to also serve as the analyzer. This is the only way to examine communications with an internal modem, though it doesn't reveal as much as a WAN-side interface (such as ISDNView) would. Serialtest displays RS-232 control lead information in real time or as a post-process display. Multiple windows on the data (summary, detail, hex dump and control lead) are kept in sync as you step through events.

Serialtest provides excellent session-summary details, including bytes, frames, overruns, errors and utilization statistics. In contrast, Klos SerialView provides only the highest level of received/accepted/errored frame counts. Serialtest also features a simple traffic generator, which can send a byte pattern or a file over the serial port. It does not currently support playback of captured PPP sessions.