Limitations

Range Limitations

rvtrace cannot examine packets unless they traverse the immediate network segment in which rvtrace is running. For example, point-to-point conversations within or between other network segments are invisible to rvtrace. Most saliently, retransmission requests and retransmission rejections are point-to-point packets, so they are visible to rvtrace only when they either originate or terminate in the local network segment. Consequently, in some situations rvtrace can detect retransmission broadcasts, even though it cannot detect the point-to-point packets that request retransmissions.

Switched network environments (such as switched Ethernet, or ATM) further limit the usefulness of rvtrace as a diagnostic tool. Since switching hardware forwards every point-to-point packet directly to its destination host, rvtrace detects point-to-point packets only when they either originate or terminate in the computer running rvtrace. In some switched networks, you can ameliorate this situation by disabling switching behavior—for example, by setting one port to diagnostic mode, or by using a diagnostic utility. This tactic can yield the full stream of point-to-point packets in a limited portion of the network; run rvtrace in that portion.

In addition, some network switching hardware can route multicast packets to a network segment only when a host in the segment is actually listening to the corresponding multicast group. Such high specificity further limits the range of rvtrace.

Interface Limitation

rvtrace supports only Ethernet interfaces.

rvtrace does not support these (or any other) non-Ethernet interfaces: Token Ring, FDDI, ATM.

Platform Support and Limitations

rvtrace operates on all platforms that Rendezvous supports—except z/OS.

TIBCO supports rvtrace on Microsoft Windows platforms, but requires that you first obtain and install WinPcap (see Obtaining pcap).

Warning	However, we do not support rvtrace on Windows SMP (Symmetric Multi-Processor) platforms at this time. WinPcap does not support SMP platforms, and might not operate correctly in multiprocessor environments. For more information, see www.winpcap.org/misc/faq.htm.
Note	On Windows platforms, we strongly recommend that you upgrade to the most recent version of WinPcap.

Note	UnixWare places security restrictions on programs that open interfaces in promiscuous mode (such as pcap). To run rvtrace on UnixWare platforms, you must dedicate a separate physical interface for that purpose.

Note	Mac OS X does not support rvtrace.