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[ns] Strange Result
Hi,
I've been using NS-2 to do wireless simulations. While I was trying to
evaluate the effect of Queue length on the network performance, I came
up on a very strange result. I simulated a small network with 5 nodes
and 3 cbr sources, moving in an area of 500m X 500m, at a peak speed of
25 m/s. For a queue length of 20, I performed the simulations by varying
the number of packets sent by each source during each simulation. The
number of packets of each flow dropped was monitored. For one particular
flow, the number of packet drops shows spikes at some points. If these
points are ignored, the graph results in a smooth curve, which is very
logical. The strange part is that, if the spiked points are plotted
separately, it also results in a smooth curve. I have not been able to
understand the phenomenon, even after prolonged investigation of the
trace files. Could someone please explain me the reason for this? The
results of the simulations are shown below. The spikes are shown by flow
2 and 3. Similar results occur with different scenario files and
different Connection Patterns. Is it a bug in the ns-code, or are these
just abberations which should be ignored?
# of packets # of Packets # of Packets # of Packets Total #
of Packets
per source of flow 1 of flow 2 of flow
3 dropped (including
dropped dropped
dropped control packets)
50 1 0 0 2
53 1 0 0 2
54 0 0 0 2
57 1 0 0 2
58 1 6 0 8
61 1 0 0 2
62 1 0 0 2
64 1 0 0 2
66 1 1 0 4
69 1 0 0 4
70 1 2 0 4
73 1 0 0 2
74 1 1 0 3
76 1 0 0 2
78 1 1 0 3
80 1 0 0 3
83 1 0 0 2
85 1 9 0 11
87 1 0 0 4
88 1 9 0 11
90 1 1 0 3
93 2 0 0 2
94 1 0 0 2
97 1 0 0 2
99 1 1 0 3
100 2 0 0 2
103 1 0 0 2
105 2 0 0 3
107 1 0 1 3
108 1 0 2 4
111 1 0 0 2
112 1 0 0 2
115 1 0 0 2
117 1 12 0 14
118 1 12 0 14
120 1 0 0 2
123 1 0 0 2
124 1 0 0 2
127 0 0 0 2
128 1 0 5 7
131 1 0 0 2
132 1 14 0 16
135 1 0 0 3
137 1 0 0 2
138 1 0 0 2
140 1 14 0 16
142 1 0 0 2
145 1 0 0 2
146 1 0 9 11
148 1 0 0 2
151 1 0 10 12
153 1 0 0 3
155 1 0 0 2
156 1 0 0 2
158 1 1 0 5
160 1 1 0 3
162 1 0 12 14
165 1 0 0 2
166 1 0 13 15
169 1 0 0 2
170 1 1 0 3
172 1 0 0 2
175 1 0 15 17
176 1 0 0 2
178 0 1 0 2
180 1 1 0 4
183 1 0 0 2
185 1 0 0 2
187 1 0 17 19
189 2 0 0 4
190 1 0 0 3
192 1 20 0 22
194 1 0 19 21
197 1 0 0 2
199 1 0 0 2
200 1 0 0 3
202 1 0 0 2
205 1 22 0 24
207 1 0 0 2
208 1 1 22 25
211 1 0 0 3
213 1 1 0 3
214 1 0 24 26
217 1 0 0 3
218 1 0 0 2
220 1 0 0 2
223 1 0 0 2
225 1 23 0 25
226 1 0 0 2
229 1 0 0 2
231 1 0 0 2
233 1 1 26 29
235 1 0 0 2
237 1 0 0 2
239 1 0 28 30
241 1 0 0 2
242 1 24 0 26
245 1 0 0 2
247 1 0 29 31
248 1 29 0 31
250 1 0 0 2
252 1 0 0 2
255 1 31 0 33
257 1 0 31 33
259 1 1 0 3
260 1 0 33 35
262 1 32 0 34
264 1 0 0 2
266 1 0 0 2
269 1 0 0 2
271 1 28 0 30
272 1 0 0 2
274 1 0 36 38
277 1 0 0 2
279 1 35 0 37
281 1 0 0 3
282 1 0 0 4
285 2 0 0 3
287 1 1 0 3
289 1 0 0 2
290 1 1 0 4
292 1 0 0 3
295 1 0 0 2
296 1 1 0 3
299 1 0 0 2
300 1 1 0 3
302 2 0 0 3
304 1 0 41 43
306 1 0 0 2
308 1 1 0 3
311 1 0 0 2
313 1 0 0 2
314 1 0 0 2
316 1 2 0 4
318 1 2 2 7
320 1 2 2 6
322 1 3 2 8
324 1 3 4 9
327 2 3 47 55
329 1 3 5 10
331 1 47 6 56
333 1 5 6 13
334 1 5 8 17
336 1 6 9 17
338 1 6 10 20
340 2 5 10 18
342 1 6 11 19
344 1 7 12 23
346 1 6 12 22
349 1 7 14 23
351 1 8 14 26
353 1 8 58 68
354 1 8 59 69
357 2 9 17 30
358 2 11 17 32
360 1 10 18 32
362 1 11 18 32
364 1 11 62 75
367 2 10 20 33
368 2 43 22 68
371 2 11 22 36
372 2 11 23 37
374 1 14 24 40
376 2 13 68 84
379 1 14 26 42
380 2 14 26 43
383 2 14 27 45
385 3 14 28 46
386 2 46 28 77
388 1 15 30 49
391 2 15 31 49
393 1 15 30 47
394 1 17 32 51
396 1 16 75 93
399 1 17 33 52
400 1 18 34 54
403 2 18 78 99
405 1 20 36 60
406 1 19 37 58
409 1 19 37 58
411 2 21 38 62
413 1 20 39 61
414 3 52 40 96
417 2 20 83 106
419 1 22 42 67
420 2 65 42 110
423 1 22 43 68
424 2 22 44 70
426 1 23 45 70
429 1 25 46 75
431 2 25 47 77
432 1 26 47 75
435 1 25 49 78
436 1 25 48 75
439 3 57 50 111
441 1 25 50 78
443 1 26 94 122
444 2 27 52 84
446 1 29 53 85
449 1 27 53 84
451 3 27 98 129
453 2 30 55 90
455 1 29 99 130
457 1 29 57 89
459 1 29 101 132
460 1 32 58 92
463 2 30 59 92
464 2 30 104 137
467 1 31 61 94
468 1 32 61 96
470 1 31 62 95
473 1 32 63 97
475 2 32 107 142
477 3 33 65 102
478 1 34 66 102
480 3 33 66 103
483 3 79 67 150
484 1 35 68 105
486 3 37 69 111
489 1 36 70 109
490 3 80 70 154
493 3 38 114 156
494 1 38 72 112
497 3 69 73 146
498 3 37 117 158
Thanks.
Harpreet.