English
- # slow start protocol in normal situation
- # features : labeling, annotation, nam-graph, and window size monitoring
- set ns [new Simulator]
- $ns color 1 Red
- $ns trace-all [open B5-slow-start.tr w]
- $ns namtrace-all [open B5-slow-start.nam w]
- ### build topology with 6 nodes
- proc build_topology { ns } {
- global node_
- set node_(ss1) [$ns node]
- set node_(ss2) [$ns node]
- set node_(rr1) [$ns node]
- set node_(rr2) [$ns node]
- set node_(ss3) [$ns node]
- set node_(ss4) [$ns node]
- $node_(ss2) color "red"
- $node_(ss4) color "red"
- $node_(rr1) color "blue"
- $node_(rr2) color "blue"
- $node_(rr1) shape "rectangular"
- $node_(rr2) shape "rectangular"
- $ns at 0.0 "$node_(ss1) label TCP2-Sender"
- $ns at 0.0 "$node_(ss2) label CBR2-Sender"
- $ns at 0.0 "$node_(ss3) label TCP2-Receiver"
- $ns at 0.0 "$node_(ss4) label CBR2-Receiver"
- $ns duplex-link $node_(ss1) $node_(rr1) 0.5Mb 20ms DropTail
- $ns duplex-link $node_(ss2) $node_(rr1) 0.5Mb 20ms DropTail
- $ns duplex-link $node_(rr1) $node_(rr2) 0.5Mb 20ms DropTail
- $ns duplex-link $node_(rr2) $node_(ss3) 0.5Mb 20ms DropTail
- $ns duplex-link $node_(rr2) $node_(ss4) 0.5Mb 20ms DropTail
- $ns queue-limit $node_(rr1) $node_(rr2) 100
- $ns queue-limit $node_(rr2) $node_(rr1) 100
- $ns duplex-link-op $node_(ss1) $node_(rr1) orient right-down
- $ns duplex-link-op $node_(ss2) $node_(rr1) orient right-up
- $ns duplex-link-op $node_(rr1) $node_(rr2) orient right
- $ns duplex-link-op $node_(rr2) $node_(ss3) orient right-up
- $ns duplex-link-op $node_(rr2) $node_(ss4) orient right-down
- $ns duplex-link-op $node_(rr1) $node_(rr2) queuePos 0.5
- $ns duplex-link-op $node_(rr2) $node_(rr1) queuePos 0.5
- }
- build_topology $ns
- Agent/TCP set nam_tracevar_ true
- ### TCP between ss1 and ss3 (Black)
- set tcp2 [$ns create-connection TCP $node_(ss1) TCPSink $node_(ss3) 2]
- $tcp2 set maxcwnd_ 8
- $tcp2 set fid_ 2
- set ftp2 [$tcp2 attach-app FTP]
- $ns add-agent-trace $tcp2 tcp
- $ns monitor-agent-trace $tcp2
- $tcp2 tracevar cwnd_
- ### CBR traffic between ss2 and ss4 (Red)
- set cbr2 [$ns create-connection CBR $node_(ss2) Null $node_(ss4) 3]
- $cbr2 set packetSize_ 500
- $cbr2 set interval_ 0.05
- $cbr2 set fid_ 3
- proc finish {} {
- global ns
- $ns flush-trace
- puts "filtering..."
- exec tclsh ../bin/namfilter.tcl B5-slow-start.nam
- puts "running nam..."
- exec nam B5-slow-start.nam &
- exit 0
- }
- ### set operations
- $ns at 0.1 "$ftp2 start"
- $ns at 1.1 "$ftp2 stop"
- $ns at 0.1 "$cbr2 start"
- $ns at 1.1 "$cbr2 stop"
- $ns at 2.0 "finish"
- ### add annotations
- $ns at 0.0 "$ns trace-annotate "Normal operation of <Slow Start> with max window size, 8""
- $ns at 0.1 "$ns trace-annotate "FTP starts at 0.1""
- $ns at 0.1 "$ns trace-annotate "CBR starts at 0.1""
- $ns at 0.11 "$ns trace-annotate "Initial window size is 1""
- $ns at 0.22 "$ns trace-annotate "1 ack is coming""
- $ns at 0.26 "$ns trace-annotate "Increase window size to 2""
- $ns at 0.38 "$ns trace-annotate "2 acks are coming""
- $ns at 0.42 "$ns trace-annotate "Increase window size to 4""
- $ns at 0.55 "$ns trace-annotate "4 acks are coming""
- $ns at 0.59 "$ns trace-annotate "Increase window size to 8""
- $ns at 0.75 "$ns trace-annotate "8 acks are coming""
- $ns at 0.77 "$ns trace-annotate "Keep maximum cwnd size, 8""
- $ns at 1.1 "$ns trace-annotate "FTP stops at 1.1""
- $ns at 1.1 "$ns trace-annotate "CBR stops at 1.1""
- $ns run
