TCP in Mobile Ad Hoc Networks (MANETs)

TCP in Mobile Ad Hoc Networks(MANETs)Wireless Network Lab.

TCP(AIMD)

TCP

(Slow Start)(Congestion Avoidance)(RTO)(Fast Retransmit )(Fast Recovery)

(CWND)/(RWND)(SWND) = min(RWND, CWND)

TCPAd hoc

TCP

ACK()

Ad hocWLANAd hocTCPTCPTCPAd hoc

(1) collisionhidden terminalbit error ratio

(2) node mobilityheavy contention

(3) access medium

TCPTCP

Ad hocTCPTCP

Ad Hoc /TCP:

TCPTCP

TCP-F( TCPFeedback )ELFNATCP()

TCPACK

(fixed RTO)ACK (Dynamic delay ACK)TCP(TCP DoorTCP Detecting out of order and Response)

TCP NS2

NS2NSNSns/tcl/libns-deafult.tclNSset

NS:

(1):;at;run(2):namtrace(3):;

(4):agent

(5):FTPCBR;agent.

(6):at(7):

---nodeslinksagents

simulatornodeSimplex-linkDuplex-link

Agents agentsagentsagents agents/typetypeagents

agents simulatorattach-agentsagents

agentagentattach-sourceattach-trafficagent

#===================================# Agents Definition #===================================set tcp_(0) [$ns_ create-connection TCP $node_(0) TCPSink $node_(1) 0]$tcp_(0) set window_ 32$tcp_(0) set packetSize_ 512set ftp_(0) [$tcp_(0) attach-source FTP]$ns_ at 0.0 "$ftp_(0) start"

TCP Agent agent agent

agent sink

agent

TCP agent Agent/TCP - a tahoe TCP sender Agent/TCP/Reno - a Reno TCP sender Agent/TCP/Newreno - Reno with a modification Agent/TCP/Sack1 - TCP with selective repeat (follows RFC2018) Agent/TCP/Vegas - TCP Vegas Agent/TCP/Fack - Reno TCP with forward acknowledgment

TCP agent Agent/TCPSink - TCP sink with one ACK per packet Agent/TCPSink/DelAck - TCP sink with configurable delay per ACK Agent/TCPSink/Sack1 - selective ACK sink (follows RFC2018) Agent/TCPSink/Sack1/DelAck - Sack1 with DelAck

#TCP RenoFTP

set tcp1 [new Agent/TCP/Reno]$tcp1 set window_ 24$tcp1 set fid_ 2$ns attach-agent $n2 $tcp1set tcp1sink [new Agent/TCPSink]$ns attach-agent $n3 $tcp1sink$ns connect $tcp1 $tcp1sinkset ftp1 [new Application/FTP]$ftp1 attach-agent $tcp1

#TCP VegasFTP $set tcp0 [new Agent/TCP/Vegas] $tcp0 set v_alpha_ 1 $tcp0 set v_beta_ 3 $tcp0 set window_ 24 $tcp0 set fid_ 1 $ns attach-agent $n0 $tcp0 set tcp0sink [new Agent/TCPSink] $ns attach-agent $n1 $tcp0sink $ns connect $tcp0 $tcp0sink set ftp0 [new Application/FTP] $ftp0 attach-agent $tcp0

Configuration Parameters

Agent/TCP set window_ 20 ;# max bound on window sizeAgent/TCP set windowInit_ 1 ;# initial/reset value of cwndAgent/TCP set windowOption_ 1 ;# cong avoid algorithm (1: standard)Agent/TCP set windowConstant_ 4 ;# used only when windowOption != 1Agent/TCP set windowThresh_ 0.002 ;# used in computing averaged windowAgent/TCP set overhead_ 0 ;# !=0 adds random time between sendsAgent/TCP set ecn_ 0 ;# TCP should react to ecn bitAgent/TCP set packetSize_ 1000 ;# packet size used by sender (bytes)Agent/TCP set bugFix_ true ;# see explanationAgent/TCP set slow_start_restart_ true ;# see explanationAgent/TCP set tcpTick_ 0.1 ;# timer granulatiry in sec (.1 is NONSTANDARD)Agent/TCP set maxrto_ 64 ;# bound on RTO (seconds)Agent/TCP set dupacks_ 0 ;# duplicate ACK counterAgent/TCP set ack_ 0 ;# highest ACK received

TCP under NS2

Functions for Sending Data

Functions for Window Management

Functions for Processing ACKs

send_much (force, reason, maxburst ) maxburst_

output (seqno, reason) maxseq_TCP

Functions for Window Management windowwnd_wnd_advertised

opencwnd() ACK ACKcwnd_cwnd_

closecwnd(int how) ECN how 0 Tahoe TCP TCP ssthresh_1/21 Reno TCP 2 ECN ssthresh_

Functions for Processing ACKs recv() ACK ACK ts_peer_ACK timestampECN ACK newack(),ACK seen send_much

newack() ACKACK ACKnewtimer()