Re: [ns] packet size in the trace file

["Jun Zhao" <JZhao_NS@hotmail.com>]

28 bytes? Just the same size as the MAC header of 802.11 (remove address4,
which is 6 bytes).
Try to check the files which add and remove headers.
----- Original Message -----
From: "Danaus" <danausli@263.net>
To: <ns-users@ISI.EDU>
Sent: Tuesday, August 28, 2001 12:36 AM
Subject: [ns] packet size in the trace file


>
> Hi:
>
> For test DSR in NS2, I setup a two wireless nodes top, say node0 and
node1.
> Infact, in my scenario these two nodes are actionless and connected by
> a FTP traffic source because I just want to see if it can work.
>
> The following is a segment of my trace file
> (line number is added by me for explaining easily):
> ---------
> 1:  M 0.0 nn 2 x 670 y 670 rp DSR
> 2:  M 0.0 sc ./scene/dsr-scen-2 cp ./scene/dsr-cp-2 seed 0.0
> 3:  M 0.0 prop Propagation/TwoRayGround ant Antenna/OmniAntenna
> 4:  Sconfig 0.00000 using MOBICACHE
> 5:  s 0.000000000 _1_ AGT  --- 0 tcp 40 [0 0 0 0] ------- [1:0 0:0 32 0]
[0 0] 0 0
> 6:  r 0.012924572 _0_ AGT  --- 0 tcp 68 [a2 0 1 800] ------- [1:0 0:0 32
0] [0 0] 1 0
> 7:  s 0.012924572 _0_ AGT  --- 3 ack 40 [0 0 0 0] ------- [0:0 1:0 32 0]
[0 0] 0 0
> 8:  r 0.014406572 _1_ AGT  --- 3 ack 68 [a2 1 0 800] ------- [0:0 1:0 32
1] [0 0] 1 0
> 9:  s 0.014406572 _1_ AGT  --- 4 tcp 1000 [0 0 0 0] ------- [1:0 0:0 32 0]
[1 0] 0 0
> 10: s 0.014406572 _1_ AGT  --- 5 tcp 1000 [0 0 0 0] ------- [1:0 0:0 32 0]
[2 0] 0 0
> 11: r 0.019868572 _0_ AGT  --- 4 tcp 1028 [a2 0 1 800] ------- [1:0 0:0 32
0] [1 0] 1 0
> 12: s 0.019868572 _0_ AGT  --- 6 ack 40 [0 0 0 0] ------- [0:0 1:0 32 0]
[1 0] 0 0
> 13: r 0.024971239 _0_ AGT  --- 5 tcp 1028 [a2 0 1 800] ------- [1:0 0:0 32
0] [2 0] 1 0
> 14: s 0.024971239 _0_ AGT  --- 7 ack 40 [0 0 0 0] ------- [0:0 1:0 32 0]
[2 0] 0 0
> 15: r 0.026153239 _1_ AGT  --- 6 ack 68 [a2 1 0 800] ------- [0:0 1:0 32
1] [1 0] 1 0
> 16: s 0.026153239 _1_ AGT  --- 8 tcp 1000 [0 0 0 0] ------- [1:0 0:0 32 0]
[3 0] 0 0
> 17: s 0.026153239 _1_ AGT  --- 9 tcp 1000 [0 0 0 0] ------- [1:0 0:0 32 0]
[4 0] 0 0
> 18: r 0.031175239 _0_ AGT  --- 8 tcp 1028 [a2 0 1 800] ------- [1:0 0:0 32
0] [3 0] 1 0
> 19: s 0.031175239 _0_ AGT  --- 10 ack 40 [0 0 0 0] ------- [0:0 1:0 32 0]
[3 0] 0 0
> 20: r 0.032537239 _1_ AGT  --- 7 ack 68 [a2 1 0 800] ------- [0:0 1:0 32
1] [2 0] 1 0
> 21: s 0.032537239 _1_ AGT  --- 11 tcp 1000 [0 0 0 0] ------- [1:0 0:0 32
0] [5 0] 0 0
> 22: s 0.032537239 _1_ AGT  --- 12 tcp 1000 [0 0 0 0] ------- [1:0 0:0 32
0] [6 0] 0 0
> 23: r 0.037659239 _0_ AGT  --- 9 tcp 1028 [a2 0 1 800] ------- [1:0 0:0 32
0] [4 0] 1 0
> 24: s 0.037659239 _0_ AGT  --- 13 ack 40 [0 0 0 0] ------- [0:0 1:0 32 0]
[4 0] 0 0
> 25: r 0.039081239 _1_ AGT  --- 10 ack 68 [a2 1 0 800] ------- [0:0 1:0 32
1] [3 0] 1 0
> ...
> ---------
>
> From the file we can see that node1 send a packet to node0 (line 5) and
> then node0 receive this packet (line 6).
>
> *MY QUESTION* is why the packet size in line 5 and line 6 is different?
> In line 5 is 40 bytes and in line 6 is 68 bytes.
>
> Similar phenomena can be seen at other places in this file.
> (line 10 and 11, line 22 and 23 ...)
> It seems that the packet is 28 bytes larger when it is received.
> Where are these bytes come from?
>
> Is this a bug in ns?
>
> My system is NS2.1b8a + Redhat 7.1? Could any one give me some advice?
>
> Thanks!
>
> Danaus
>
>