RED dropping packets bug?

[Pavlin Ivanov Radoslavov <pavlin@catarina.usc.edu>]

There is something odd with packets dropping behavior for RED and
DropTail queues:

If I change the 800Kb link of net0 (test-suite.tcl) from DropTail to
RED and compare the xgraph output, the DropTail packet lost at time
1.9 does not appear for RED. With other words, DropTail drop a
packet because of queue overflow, but there is no such queue
overflow for RED, which doesn't make any sense.

Below is the command + the simple patch I used to test it:

pavlin@rumi[42] ns test-suite.tcl reno net0


--- test-suite.tcl.org	Fri Oct 24 18:03:02 1997
+++ test-suite.tcl	Fri Oct 24 18:04:31 1997
@@ -333,7 +333,7 @@
     $self instvar node_
     $ns duplex-link $node_(s1) $node_(r1) 8Mb 5ms DropTail
     $ns duplex-link $node_(s2) $node_(r1) 8Mb 5ms DropTail
-    $ns duplex-link $node_(r1) $node_(k1) 800Kb 100ms DropTail
+    $ns duplex-link $node_(r1) $node_(k1) 800Kb 100ms RED
     $ns queue-limit $node_(r1) $node_(k1) 6
     $ns queue-limit $node_(k1) $node_(r1) 6
     if {[$class info instprocs config] != ""} {


Thanks,
Pavlin

P.S. Verified both for ns-2.0a17 and 2.1b1