ns: Change History

v1.1

• Added ssthresh estimation and other changes suggested by Janey Hoe to newreno. Code provided by Mark Allman.
• Corrects TcpAgent::closecwnd() bug in which ssthresh could be reduced below 2 MSS during congestion. Fix provided by Jamshid Mahdavi and Matt Mathis.
• Added code for Fack TCP, contributed by Jamshid Mahdavi and Matt Mathis from Pittsburgh Supercomputing Center.
• Added ability to use either Drop-Tail or RED queue management within a single CBQ class.
• Modified and tested red.cc implementation of "bytes" set to true, for RED packet-dropping probabilities proportional to the packet size in bytes.
• Added flow.cc, to keep per-flow statistics about the set of packets dropped by RED or Drop-Tail gateways.

v1.0 Tue Jul 23 11:27:17 PDT 1996

• Added a hook to dump a stack trace and exit when a background error is encounter (i.e., an error in a proc scheduled with ns-at). This makes it MUCH easier to debug simulator scripts that have syntax erros and what not in scheduled tcl stubs.
• Removed sack-tcp.cc from distribution. This leaves tcp-sack1.cc as the only SACK TCP implementation distributed with ns.
• Put back hook to source "~/.ns.tcl" since people rely on this. Fix provided by John Wroclawski.

v1.0b4 Mon May 6 22:22:31 PDT 1996

• Corrected fix to TCP's window decrease algorithm in v1.0b2. Now, after a Reno Fast Retransmit, the window decreases to min(cwnd_, wnd_)/2, not to cwnd_/2 (before v1.0b2) or to min(cwnd_ + dupwnd_, wnd_)/2 (as in v1.0b2,3).
• Corrected calculation of congestion window for NewReno TCP for the case when multiple packets are dropped from a single window of data.
• Fixed bug in tcp-sink.cc that allowed an infinite loop under some circumstances when the number of outstanding packets in TCP was exactly MWS-1. Also added a note to the man page about MWS and other constants in ns. Thanks to Bernhard Suter for the bug report and fix.
• In TCP, changed the constant TCP_TICK to the variable tcp_tick_, with the default set in ns_default.tcl.

v1.0b3 Mon Apr 29 19:10:33 PDT 1996

• Ported to Tcl v7.5. Changed trace objects to use new Tcl_Channel abstraction (for O/S indepedence). ns will NOT compile with earlier versions of Tcl.
• Added the parameter "maxcwnd", for the maximum congestion window, and corrected the use of "window", the receiver's advertised window, in the reno and sack implementations of TCP.
• Changed some of the *.tcl scripts to take into account the corrected use of the receiver's advertised window, and to use "maxcwnd".

v1.0b2 Fri Mar 29 16:40:25 PST 1996

• Changed interpreter to not source ".ns.tcl" since tcl no longer uses the tcl_RcFileName C variable.
• Fixed a couple more SunPro C++ compiler problems. Patcjes from Michael Pearce.
• Corrected TCP's window decrease algorithm from "cwnd_ /= 2;" to "cwnd_ = window() / 2;". Thanks to Thomas Ziegler for the bug report.

v1.0b1 Sun Mar 3 1996

• Fixed bug in tcp.cc that caused the retransmit timeout backoff behavior never to reset. Thanks to Jamshid Mahdavi for reporting both the bug and the fix.
• Fixed bug in tcplib telnet module. Random number generator was being seeded on each call (from the system clock) rather than once at start-up. Replaced calls to random number routines with calls to Random::uniform. Thanks to Werner Vogels for reporting this bug.
• Added local explicit-join notification for experimentation with RLM.
• Added a "message" agent that allows abibtrary message packets to be sent and received using tcl.
• Moved type-specific packet fields into a "body" union. Eliminated "reason" field (rather than move it to tcp body) since we should have just used the "flags" field to begin with.
• Added tracing functionality to loss-monitor agents (e.g., so we can compute sliding window loss statistics using an external tool).
• Changed ns-now to use 17 digits of precision. Otherwise, truncation could cause certain algorithms (e.g., RLM) to try to schedule events into the past.
• Added "random" attribute to cbr sources to cause them to generate a Poisson rather than fixed-rate packet stream.
• Fixed bug in RED initialization that could cause (almost-) infinite loop at start up.
• Incorporated patches from Michael Pearce to compile with SunPro C++ v3.0.1.
• Fixed bug that caused memory corruption when using class ID's larger than 10.

v1.0a17 Thu Dec 27 1995

• Finished port of "tcp-sack1" and "sack1-tcp-sink", a second format for selective acks.
• Added "bursty" source for tcp connections.
• Added new loss policies for drop-tail links, "lossy-uniform" and "lossy-det". [Kevin Fall].
• Added more test files to the distribution: test-all-cbq, test-all-red, test-all-sack, and test-sack, in addition to test-all.

v1.0a16 Tue Dec 12 19:05:56 PST 1995

• Added source code for sack-tcp.cc.

v1.0a15 Tue Dec 12 17:52:32 PST 1995

• First cut at adding code for "tcp-sack1" and "sack1-tcp-sink", from Matt Mathis (mathis@zippy.psc.edu) and Jamshid Mahdavi (mahdavi@psc.edu).
• Changed format of window and RTT reports sent from tcp.cc to the trace file.
• Added "maxpkts" for ftp and telnet sources.

v1.0a14 Fri Dec 1 10:35:30 PST 1995

• Finished port of TCP with selective acks, along with SACK acceptance tests in "test-sack".
• Added a modified version of Reno TCP, tcp-newreno.cc, for research purposes.
• Have not yet added tcp-sack or tcp-newreno to the man page.

v1.0a13 Wed Nov 22 15:14:50 PST 1995

• Finished port of cbq code from tcpsim (with contributions from Michael Speer), and added cbq simulator tests.
• Added unique ID to each event in scheduler queue and added hook to lookup an event by using this ID.
• Added hook for deleting at callbacks.
• Fixed bugs in multicast delivery where agent could modify routing desstructors during the callback.
• First cut at port of TCP with selective acks.

v1.0a12 Sun Nov 5 21:19

• Added config.h and loss-monitor.cc to FILES so they get included in tar.

v1.0a11 Sun Nov 5 21:19

• Added loss-monitor agent, which is the same as a null-sink but calls a tcl proc whenever there is a gap in the received sequence space. Will expand functionality as necessary for MMG experiments.
• Integrated more mature tcl/c++ architecture from vic/vat. This has a major impact on the way ns objects are created and deleted, but we maintain backward compatibility with previous versions. The "ns" command is no longer implemented in C++, but rather as a library function (in ns_default.tcl) that provides glue between the old commands and the new "new/delete" interface.
• First cut at port of cbq code from tcpsim.

v1.0a10 Fri Oct 27 17:44:39 PDT 1995

• Added "flush" method to trace objects so that output can be flushed before exiting.
• Added link-level src/dst fields to Packet class so node can tell which "interface" a packet arrived on.
• Added support for dense-mode PIM style flooding with prune/graft machinery.

v1.0a10 Fri Oct 27 17:44:39 PDT 1995

• Fixed test-suite.tcl so that old awk works. Problem reported by Kannan Varadhan.
• Fixed Makefile.in to use V_LIB_TCL, as intended. Fix supplied by Kannan Varadhan.

v1.0a9 Wed Oct 11 16:58:00 PDT 1995

• Fixed solaris compilation problems.
• Changed configure to use "-mv8 -msupersparc" only for gcc.

v1.0a8 Fri Sep 29 15:11:04 PDT 1995

• Fixed more for-stmt scope bugs.
• Fixed compilation problems with Sun and DEC compilers. Problem reported by Thierry Turletti.

v1.0a7 Wed Sep 27 19:55:23 PDT 1995

• First public (alpha) release.
• Included man page to FILES so it goes in tar.
• Updated README.

v1.0a6 Sep 21 09:24 PDT 1995

• Added "bug-fix" hook to tcp reno.
• Ported to tcl-7.4.
• Include Matt Mathis' test-all script.
• Changed "for" statement conventions to adhere to the proposed ANSI standard change which re-defines the lexical scope semantics of the initializer statement. In order to be compatible with both the old and new semantics, we have changed all instances of
  • for (int i = ... ) ...
  • use(i);
  to
  • int i;
  • for (i = ... ) ...
  • use(i);

v1.0a4

• Fixed bug in xgraph output: new version of xgraph doesn't understand FileorDev because it now uses the PRINTER environment variable. Bug fix from Matt Mathis (mathis@psc.edu).
• Added a 'test-all' sh script to distribution, which runs whole suite of regression tests and compares them against a reference output. Thanks to Matt Mathis (mathis@psc.edu).
• Don't include tk.h from Tcl.cc.

v1.0a1 Mon Jul 31 16:05:08 PDT 1995

• Changed all references to random() to use Random class so we can easily change our pseudo-random number generator.
• Added convention to object names so we can derive their type from their name.
• Changed nodes to be first class objects like rest of objects.
• Changed trace syntax to use tcl files rather than it's own open/close. For example,
  • set f1 [open out.hop w]
  • $trace attach $f1
• Changed '-' and 'd' trace records to have same format as '+' and 'h' trace records.
• Incoporate vic's "matcher" abstraction into agent and link models.
• Major hacking to port tcpsim to tcl framework.