Unfortunately, Serialtest doesn't have the ability to trigger a capture session based on an event such as activity on a particular TCP port. There's no ability to filter for certain packet types in real time or in post-capture processing. These are critical elements of any protocol analyzer, and we're surprised at the omission. Frontline says these features will be available in a later release.

Send your comments on this article to David Willis at dwillis@nwc.com.

How We Tested PPP Analyzers
Our PPP analyzer tests focused on typical problems found with dial-up communications. First, three successful Windows98 dial-up networking sessions were recorded, running a variety of applications including IP ping, Lotus Notes and a Web browser. Next, we examined common PPP negotiation problems, including incorrect passwords, bad IP address assignment, lack of a common network-layer protocol, authentication-protocol mismatch and lack of support for encryption at the remote-access server.

We collected data via two interfaces for each product. Frontline Test Equipment's Serialtest spy mode analyzed packets from the PC running the dial-up client. Serialtest Async used a custom cable set to collect data from the RS-232 cable. Likewise, Klos Technologies' SerialView used its own cable configuration. Finally, we used Klos ISDNView with ORION Development Corp.'s ByteGrabber to snoop at the interface into the ISDN network itself.

Packets were collected via all analyzers simultaneously, allowing us to directly compare the products using the same data.