ns: Change History

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.

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".

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.

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.

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.

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.

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.

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.

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.

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.

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.

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

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.

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.