[ns] Question about ARP timeout

[Zhenqiang Ye <zye@cs.ucr.edu>]

 Hi, there:
   I am using ns-2 to simulate ad-hoc network. I have four nodes in my
 simulation, which are:


             ----------node 1------------
       	     |                          |
  node 0 ----|                          |--node 3
 	     |                          |
 	     |---------node 2------------


 node 0 send tcp packets through 1 and 2 (I use multipath) to node 3. The
 routing protocol is DSR.

 When I study the trace file, I found that when node 2 send a ARP packet to
 node 0 at t=0.033905127, the ARP is time out at t=0.056163127, and the
 packet 2 is dropped. My question is the ARP_timeout is set to be 0.03 in
 dsragent.cc, it seems like packet 2 is dropped earlier than expected.
 Any reply for the question will be appreciated.


 r 0.032666627 _3_ MAC  --- 0 ARP 28 [a2 3 2 806] ------- [REPLY 2/2 3/3]
 s 0.033905127 _2_ MAC  --- 0 ARP 80 [0 ffffffff 2 806] ------- [REQUEST 2/2 0/0]
 r 0.034225127 _1_ MAC  --- 0 ARP 28 [0 ffffffff 2 806] ------- [REQUEST 2/2 0/0]
 r 0.034225960 _3_ MAC  --- 0 ARP 28 [0 ffffffff 2 806] ------- [REQUEST 2/2 0/0]
 r 0.034225960 _0_ MAC  --- 0 ARP 28 [0 ffffffff 2 806] ------- [REQUEST 2/2 0/0]
 D 0.056163127 _2_ IFQ  ARP 2 DSR 44 [a2 2 2 800] ------- [3:255 0:255 255 0] 3 [0 1] [1 1 3 0->3] [0 0 0 0->0]
 s 0.056510127 _2_ MAC  --- 0 ARP 80 [0 ffffffff 2 806] ------- [REQUEST 2/2 0/0]
 r 0.056830127 _1_ MAC  --- 0 ARP 28 [0 ffffffff 2 806] ------- [REQUEST 2/2 0/0]
 r 0.056830960 _3_ MAC  --- 0 ARP 28 [0 ffffffff 2 806] ------- [REQUEST 2/2 0/0]
 r 0.056830960 _0_ MAC  --- 0 ARP 28 [0 ffffffff 2 806] ------- [REQUEST 2/2 0/0]
 s 0.058735293 _0_ MAC  --- 0 ARP 80 [a2 2 0 806] ------- [REPLY 0/0 2/2]
 r 0.059056127 _2_ MAC  --- 0 ARP 28 [a2 2 0 806] ------- [REPLY 0/0 2/2]
 s 0.060856293 _0_ MAC  --- 0 ARP 80 [a2 2 0 806] ------- [REPLY 0/0 2/2]
 r 0.061177127 _2_ MAC  --- 0 ARP 28 [a2 2 0 806] ------- [REPLY 0/0 2/2]


 Frank