[My apologies to those of you who will receive multiple copies of this announcement from other mailing lists ...] The paper "Automated Packet Trace Analysis of TCP Implementations", to appear in SIGCOMM '97, is now available from: ftp://ftp.ee.lbl.gov/papers/vp-tcpanaly-sigcomm97.ps.Z I've appended the abstract. Vern Automated Packet Trace Analysis of TCP Implementations Vern Paxson Network Research Group Lawrence Berkeley National Laboratory vern@ee.lbl.gov We describe "tcpanaly", a tool for automatically analyzing a TCP implementation's behavior by inspecting packet traces of the TCP's activity. Doing so requires surmounting a number of hurdles, including detecting packet filter measurement errors, coping with ambiguities due to the distance between the measurement point and the TCP, and accommodating a surprisingly large range of behavior among different TCP implementations. We discuss why our efforts to develop a fully general tool failed, and detail a number of significant differences among 8 major TCP implementations, some of which, if ubiquitous, would devastate Internet performance. The most problematic TCPs were all independently written, suggesting that correct TCP implementation is fraught with difficulty. Consequently, it behooves the Internet community to develop testing programs and reference implementations.