Hi Dan, still getting dropped ACKS from node1 with column4=IFQ, indicating dropped because of queue??? Is tis some sort of NS error? Am I correct in thinking that this isn't a feature of the network/protocol and it should be ignored in my analysis?
L >From: Dan Dechene <[EMAIL PROTECTED]> >To: 'Lars Lars' <[EMAIL PROTECTED]> >Subject: RE: [ns] TCP over 802.11b dropping ACKs >Date: Tue, 19 Dec 2006 18:06:43 -0500 > >This shouldn't happen. However try: > >Queue/DropTail/PriQueue as interface queue type instead of Queue/DropTail > >Dan Dechene, B.Eng. > >-----Original Message----- >From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf >Of Lars Lars >Sent: Tuesday, December 19, 2006 5:29 PM >To: ns-users@ISI.EDU >Subject: [ns] TCP over 802.11b dropping ACKs > > >Hi, > I've a 2-node(static) wireless link(802.11b). The tracefile is showing >me >that ACK packets being sent from node1 to node0 are being dropped(which is >OK), however, the fourth column in the tracefile is IFQ which implies that >these packets are being dropped due to the ifq. How can this be? PAckets on >the return path don't enter a queue at any point surely??? My simulation is >transferring FTP data from node0 to node1. The TCP agent is on node0 and >the > >sink is on node1. below is a section from my trace file. What does IFQ mean >in column 4. If (as I understand it) this means that these packets are >being > >dropped by the ifq, then why is there an IFQ on the return path as all the >traffic is going from node0 to node1? (My simulation script is below also). > >Thanks > >L > >D 30.32288741 _0_ IFQ --- 15598 tcp 1084 [0 >D 30.34824777 _0_ IFQ --- 15611 tcp 1084 [0 >D 30.62936723 _1_ IFQ --- 15759 ack 60 [0 >D 30.6869282 _1_ IFQ --- 15792 ack 60 [0 >D 30.70534317 _1_ IFQ --- 15801 ack 60 [0 >D 30.72629153 _1_ IFQ --- 15813 ack 60 [0 > > >set val(chan) Channel/WirelessChannel ;# channel type >set val(prop) Propagation/TwoRayGround ;# radio-propagation >model >set val(netif) Phy/WirelessPhy ;# network interface >type >set val(mac) Mac/802_11 ;# MAC type > Mac/802_11 set dataRate_ 11Mb ;# Data Rate >11 Mbps > Mac/802_11 set basicRate_ 1Mb ;# Basic >Rate 1 Mbps ># Mac/802_11 set RTSThreshold_ 3000 ;# Turn off >RTS / CTS > Mac/802_11 set SlotTime_ 0.000020 ;# 20us > Mac/802_11 set sifs_ 0.000010 ;# 10us > Mac/802_11 set PreambleLenght_ 144 ;# 144 bits > Mac/802_11 set PLCPHeaderLength_ 48 ;# 48 bits > Mac/802_11 set PLCPDataRate_ 1Mb ;# 1Mbps > >set val(ifq) Queue/DropTail ;# interface queue type/PriQueue >set val(ll) LL ;# link layer type >set val(ant) Antenna/OmniAntenna ;# antenna model >set val(ifqlen) 10 ;# max packet in ifq >set val(nn) 2 ;# number of mobilenodes >set val(rp) DSDV ;# routing protocol DSDV > >set ns [new Simulator] > >$ns color 0 blue >$ns color 1 red > ># set up topography object >set topo [new Topography] >$topo load_flatgrid 400 200 > >#Open the trace file >set tf [open out.tr w] >$ns trace-all $tf > >#Open the nam trace file >set nf [open out.nam w] >$ns namtrace-all-wireless $nf 400 200 > ># Create God >create-god $val(nn) > >Agent/DSDV set perup_ 15000000 ;# ~ infinite periodic update > > $ns node-config -adhocRouting $val(rp) \ > -llType $val(ll) \ > -macType $val(mac) \ > -ifqType $val(ifq) \ > -ifqLen $val(ifqlen) \ > -antType $val(ant) \ > -propType $val(prop) \ > -phyType $val(netif) \ > -channelType $val(chan) \ > -topoInstance $topo \ > -agentTrace OFF \ > -routerTrace OFF \ > -macTrace ON \ > -movementTrace OFF > > > ># Create and configure nodes >set nodeA [$ns node] >$nodeA random-motion 0 >$nodeA set X_ 100.0 >$nodeA set Y_ 100.0 >$nodeA set Z_ 0.0 > >set nodeB [$ns node] >$nodeB random-motion 0 >$nodeB set X_ 300.0 >$nodeB set Y_ 100.0 >$nodeB set Z_ 0.0 > >$ns at 0.0 "$nodeA setdest 100.0 100.0 0.0" >$ns at 0.0 "$nodeB setdest 300.0 100.0 0.0" > > ># Setup TCP Connection >set tcpA [new Agent/TCP] >$ns attach-agent $nodeA $tcpA >$tcpA set packetSize_ 1024 >set tcpSinkB [new Agent/TCPSink] >$ns attach-agent $nodeB $tcpSinkB > >$ns connect $tcpA $tcpSinkB > ># Setup FTP over TCP Connection >set ftpA [new Application/FTP] >$ftpA attach-agent $tcpA >$ftpA set type_ FTP > ># Schedule simulation events > >$ns at 1.0 "$ftpA start" >$ns at 31.0 "$ftpA stop" >$ns at 31.0000001 "stop" >$ns at 31.0000002 "puts \"NS EXITING...\" ; $ns halt" > >proc stop {} { > global ns tf nf > $ns flush-trace > close $nf > close $tf > exit 0 >} > >puts "Starting Simulation..." >$ns run > >_________________________________________________________________ >Find accommodation FAST with MSN Search! http://search.msn.ie/ > _________________________________________________________________ Find a baby-sitter FAST with MSN Search! http://search.msn.ie/