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Digital Trace Facility (DTF)
DTF is a utility which traces packets as they traverse through the protocol
layers within a router. It is a superset of Digital's CTF, supporting multiple
platforms and TCP/IP networks.
A Brief Overview of DTF
The Digital/DECNIS Trace Facility (DTF) is an enhancement to CTF (Common
Trace Facility) provided in DECnet/OSI. DTF provides support for TCP (in
addition to DECnet) as the transport protocol over which the trace records
are collected, and it runs on multiple host platforms, namely VMS, Digital
Unix, and Windows NT/95. DTF traces packets as they pass through the protocol
layers of the router and displays the decoded packet on the host or records
the trace data in a file for later analysis. DTF includes facilities for,
filtering certain packet types at the source, filtering the output using
regular expressions, performing validity check on packets, and displaying
the output in full, brief or raw formats.
Tracing occurs through tracepoints which are, usually positioned in
the transmit and receive routines of the protocol modules in the Router.
Each tracepoint has a name and state, when a packet (IORB) passes through
a tracepoint and that tracepoint is in the ON state then it is copied and
queued to the DTF module in the router which will, some time later, transmit
it over the TCP connection to the host. The host specifies the name(s)
of the tracepoints it wants to activate in the initial connection request,
these tracepoints then remain active until the connection is closed.
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