hi, Ahmad: ======= 2006-04-03 02:05:24 Ahmad Khayyat wrote: =======
>Hi Bruce, > >If you enable AGT and RTR tracing (in node-config command in the tcl >file), you will see that when a tcp packet is sent out of the RTR layer, >its size is larger than its size when sent by the AGT layer. This >reflects the fact that the RTR layer adds some headers that contribute >to the packet size. The same thing happens when the packet is sent by >the MAC layer; it gets a little bigger due to MAC headers. > >For the inconsistent packet size in the MAC layer between send time and >recv time, my guess is that the packet size is measured in the receive >event after removing the MAC headers. You will see that the received >packet size in the MAC is equal to the packet size sent by RTR, which is >the size before adding the MAC headers. Having that said, my guess is >that the packet size reported in the send event is the correct size sent >out of the MAC layer. In that case, the packet size in the receive event >is the size that the MAC layer reports to higher layers. I agree with you. I find that all beacon/ack packets are exactly 7 bytes. I guess this is a bug of ns2? And I still cannot apply lossmodel to wpan. I modified ns-2.29\tcl\ex\wpan\wpan_demo2.tcl this way: ============================================================= proc seterrmodel { src dst } { global ns_ val node_ set errmodel [new ErrorModel] $errmodel set rate_ $val(per) $errmodel set unit_ $val(errUnit) eval $ns_ lossmodel $errmodel \$node_($src) \$node_($dst) } ... seterrmodel 0 1 ============================================================= I added above code into wpan_demo2.tcl, and got the following traceback: $ ns wpan_demo2.tcl num_nodes is set 7 INITIALIZE THE LIST xListHead Traffic: ftp Acknowledgement for data: on invalid command name "" while executing "$link errormodule $lossobj" (procedure "_o3" line 3) (Simulator lossmodel line 3) invoked from within "_o3 lossmodel _o158 $node_(0) $node_(1)" ("eval" body line 1) invoked from within "eval $ns_ lossmodel $errmodel \$node_($src) \$node_($dst)" (procedure "seterrmodel" line 7) invoked from within "seterrmodel 0 1" invoked from within "if { "$val(traffic)" == "ftp" } { puts "\nTraffic: ftp" #Mac/802_15_4 wpanCmd ack4data off puts [format "Acknowledgement for data: %s" [Mac/8..." (file "wpan_demo2.tcl" line 231) Could anyone give me any clue? > > >Bruce Who wrote: > >>hi, Ahmad: >> >>======= 2006-03-31 23:40:43 Ahmad Khayyat wrote: ======= >> >> >> >>>2) assoPermit means whether the node should permit other nodes to >>>associate with it so that it becomes their coordinator. Look at the >>>802.15.4-2003 standard for details. >>> >>>5) This is not how LossModel is used. Consult ns-manual for the correct >>>usage. It still applies for wpan. >>> >>> >> >>Thanks, I'll look into the document. >> >>And I have another question. This is a snippet from wpan_demo2.tr, I find >>that all tcp packets sent out is always 7 bytes bigger than the received >>packets. Why do they not have the same size? Then which one(97 or 90) is the >>real size of the tcp packets? >> >>s 11.928192000 _0_ MAC --- 255 tcp 97 [0 5 0 800] ------- [0:2 5:0 30 5] >>[133 0] 0 0 >>s 11.931712033 _5_ MAC --- 255 ACK 5 [0 0 5 0] >>r 11.932064067 _0_ MAC --- 255 ACK 5 [0 0 5 0] >>r 11.932704033 _5_ MAC --- 255 tcp 90 [0 5 0 800] ------- [0:2 5:0 30 5] >>[133 0] 1 0 >> >> >> >>>Bruce Who wrote: >>> >>> >>> >>>>------------------------------------------------------------------------ >>>> >>>>Hi, all: >>>> >>>>Recently I begin to learn how to use ns2 to run wpan simulations, and >>>>stumbled >>>>by some problems, hope someone could help me out. >>>> >>>>1)I found there are some commands like this: >>>>eval $ns_ attach-agent \$node_($src) \$udp_($src) >>>> >>>>why don't we just use this command? >>>> >>>>$ns_ attach-agent $node_($src) $udp_($src) >>>> >>>>2) for this command >>>>$node sscs startCTDevice <isFFD = 1> <assoPermit = 1> <txBeacon = 0> >>>><beaconOrder = 3> <SuperframeOrder = 3> >>>> >>>>what does assoPermit mean? >>>> >>>>3) I ran wpan_demo2.tcl and found that all extended addresses of nodes are >>>> [0]. Is it necessary to set the address to different values by ourselves? >>>> >>>>4) I ran "nam wpan_demo2.nam" and found that data stream is only seem >>>>between >>>> PANCoor(node0) and node1. But we have such statements in the >>>> wpan_demo2.tcl >>>> script: >>>> >>>> ftptraffic 0 1 $appTime1 >>>> ftptraffic 0 3 $appTime3 >>>> ftptraffic 0 5 $appTime5 >>>> >>>>So why could no communications be seen between node0 and node3/node5? >>>> >>>>5) And how to set lossmodel for nodes in wpan? I tried following code, but >>>>it >>>> doesn't work: >>>> >>>>set loss_module [new ErrorModel] >>>>$loss_module set rate_ 0.01 >>>>$loss_module unit pkt >>>>$loss_module ranvar [new RandomVariable/Uniform] >>>>$loss_module drop-target [new Agent/Null] >>>>eval $ns lossmodel $loss_module \$node_($src) \$node_($dst) >>>> >>>>Any help would be appreciated! Thanks in advance! >>>> >>>> >>>> >>>>Best regards, >>>> >>>>Bruce Who >>>> >>>> >>>> >>>> >>>> >> >>= = = = = = = = = = = = = = = = = = = = >> >>Best regards, >> >> Bruce Who >> 2006-04-02 >> >> >> > = = = = = = = = = = = = = = = = = = = = Best regards, Bruce Who 2006-04-03