[ns] Wrong packet size?

[Boris Kock <bakock@kom.auc.dk>]

Hi,

When I was running some mobile IP simulations and looked at the tracefile
I saw that the simulated packet size (ch->size()) of registration request
messages changes.
When send from the Mobile Host (MH) the packets are 52 bytes. From the
Foreign Agent (FA) to the Home Agent (HA) and back the packet is 72 bytes
and when the reply arives at the MH again its 92 bytes long.

I attached part of the tracefile. Packet number 289 is the reqistration
request, node _5_ de MH, node 6 the FA and node 1 the HA. You can see the
packet size changing. 

Does anybody know why this is? 
I thought the size of the registration request should remain the same (52
bytes) during the request according to the mobile IP protocol. This value
is defined in mip-reg as REG_REQ_SIZE. It looks as if the packet is
encapsulated, but I do not know why.

Thanks,

Boris  

------------------------------------------------------------
Boris Kock
Center for PersonKommunkation
Aalborg University
s 5.757016281 _5_ AGT  --- 289 udp 52 [0 0 0 0] ------- 0 [0.0.1.0 2.0.0.0 32 8388608] 

s 5.757091281 _5_ MAC  --- 0 MAC 44 [33e 2 1 0] 

r 5.757267382 _6_ MAC  --- 0 MAC 44 [33e 2 1 0] 

s 5.757277382 _6_ MAC  --- 0 MAC 38 [29c 1 0 0] 

r 5.757429483 _5_ MAC  --- 0 MAC 38 [29c 1 0 0] 

s 5.757479483 _5_ MAC  --- 289 udp 124 [a2 2 1 800] ------- 0 [0.0.1.0 2.0.0.0 32 8388608] 

r 5.757975585 _6_ MAC  --- 289 udp 72 [a2 2 1 800] ------- 0 [0.0.1.0 2.0.0.0 32 8388608] 

s 5.757985585 _6_ MAC  --- 0 MAC 38 [0 1 0 0] 

r 5.758000585 _6_ AGT  --- 289 udp 72 [a2 2 1 800] ------- 0 [0.0.1.0 2.0.0.0 32 8388608] 

s 5.758000585 _6_ AGT  --- 289 udp 72 [a2 2 1 800] ------- 0 [2.0.0.0 0.0.0.0 32 8388608] 

+ 5.758001 6 2 udp 72 ------- 0 2.0.0.0 0.0.0.0 0 289

- 5.758001 6 2 udp 72 ------- 0 2.0.0.0 0.0.0.0 0 289

r 5.758137686 _5_ MAC  --- 0 MAC 38 [0 1 0 0] 

r 5.759058 6 2 udp 72 ------- 0 2.0.0.0 0.0.0.0 0 289

+ 5.759058 2 1 udp 72 ------- 0 2.0.0.0 0.0.0.0 0 289

- 5.759058 2 1 udp 72 ------- 0 2.0.0.0 0.0.0.0 0 289

r 5.760116 2 1 udp 72 ------- 0 2.0.0.0 0.0.0.0 0 289

+ 5.760116 1 4 udp 72 ------- 0 2.0.0.0 0.0.0.0 0 289

- 5.760116 1 4 udp 72 ------- 0 2.0.0.0 0.0.0.0 0 289

s 5.760701272 _41_ MAC  --- 288 udp 120 [0 ffffffff 25 800] ------- 0 [4.9.0.0 1023.2047.2047.0 32 0] 

r 5.761173 1 4 udp 72 ------- 0 2.0.0.0 0.0.0.0 0 289

r 5.761173385 _4_ AGT  --- 289 udp 72 [a2 2 1 800] ------- 0 [2.0.0.0 0.0.0.0 29 8388608] 

s 5.761173385 _4_ AGT  --- 289 udp 72 [a2 2 1 800] ------- 0 [0.0.0.0 2.0.0.0 29 8388608] 

+ 5.761173 4 1 udp 72 ------- 0 0.0.0.0 2.0.0.0 0 289

- 5.761173 4 1 udp 72 ------- 0 0.0.0.0 2.0.0.0 0 289

s 5.762198040 _35_ AGT  --- 290 udp 48 [0 0 0 0] ------- 0 [4.3.0.0 1023.2047.2047.0 32 0] 

r 5.762231 4 1 udp 72 ------- 0 0.0.0.0 2.0.0.0 0 289

+ 5.762231 1 2 udp 72 ------- 0 0.0.0.0 2.0.0.0 0 289

- 5.762231 1 2 udp 72 ------- 0 0.0.0.0 2.0.0.0 0 289

r 5.763289 1 2 udp 72 ------- 0 0.0.0.0 2.0.0.0 0 289

+ 5.763289 2 6 udp 72 ------- 0 0.0.0.0 2.0.0.0 0 289

- 5.763289 2 6 udp 72 ------- 0 0.0.0.0 2.0.0.0 0 289

r 5.764346 2 6 udp 72 ------- 0 0.0.0.0 2.0.0.0 0 289

r 5.764346185 _6_ AGT  --- 289 udp 72 [a2 2 1 800] ------- 0 [0.0.0.0 2.0.0.0 26 8388608] 

s 5.764421185 _6_ MAC  --- 0 MAC 44 [38e 1 2 0] 

s 5.764436901 _35_ MAC  --- 290 udp 120 [0 ffffffff 1f 800] ------- 0 [4.3.0.0 1023.2047.2047.0 32 0] 

r 5.764597286 _5_ MAC  --- 0 MAC 44 [38e 1 2 0] 

s 5.764607286 _5_ MAC  --- 0 MAC 38 [2ec 2 0 0] 

r 5.764759388 _6_ MAC  --- 0 MAC 38 [2ec 2 0 0] 

s 5.764809388 _6_ MAC  --- 289 udp 144 [a2 1 2 800] ------- 0 [2.0.0.0 0.0.1.0 32 1] 

r 5.765385489 _5_ MAC  --- 289 udp 92 [a2 1 2 800] ------- 0 [2.0.0.0 0.0.1.0 32 1] 

s 5.765395489 _5_ MAC  --- 0 MAC 38 [0 2 0 0] 

r 5.765410489 _5_ AGT  --- 289 udp 92 [a2 1 2 800] ------- 0 [2.0.0.0 0.0.1.0 32 1] 

r 5.765547590 _6_ MAC  --- 0 MAC 38 [0 2 0 0]