There is a simple network model. Transfer a file between
host1 to
host2. Between hosts several routers with different
MTU. Here is the complete
OTcL code:
Code:
####################################################################
# #
# PRESETS #
# #
####################################################################
# new simulator object
set ns [new Simulator]
# trace file
set allchan [open /ns2/examples/data.tr w]
$ns trace-all $allchan
# for nam
set visio [open /ns2/examples/data.nam w]
$ns namtrace-all $visio
#procedure triggered at finish time
proc finish {} {
global ns visio allchan
$ns flush-trace
close $visio
close $allchan
exec nam /ns2/examples/data.nam &
exit 0
}
####################################################################
# #
# LINKS &NODES #
# #
####################################################################
set god [create-god 6]
for {set i 0} {$i < 6} {incr i} {
set node_($i) [$ns node]
}
for {set i 0} {$i < 5} {incr i} {
$ns duplex-link $node_($i) $node_([expr $i+1]) 2Mb 10ms DropTail
}
#============================= hosts ===============================
$node_(0) color Blue
$node_(5) color Blue
#============================ routers ==============================
$node_(1) color Red
$node_(2) color Red
$node_(3) color Red
$node_(4) color Red
####################################################################
# #
# AGENTS #
# #
####################################################################
set host1 [new Agent/TCP]
$ns attach-agent $node_(0) $host1
$host1 set fid_ 0
$host1 set mtu_ 1500
set router1 [new Agent/TCP]
$ns attach-agent $node_(1) $router1
$router1 set fid_ 1
$router1 set mtu_ 1000
set router2 [new Agent/TCP]
$ns attach-agent $node_(2) $router2
$router2 set fid_ 2
$router2 set mtu_ 800
set router3 [new Agent/TCP]
$ns attach-agent $node_(3) $router3
$router3 set fid_ 3
$router3 set mtu_ 700
set router4 [new Agent/TCP]
$ns attach-agent $node_(4) $router4
$router4 set fid_ 4
$router4 set mtu_ 600
set host2 [new Agent/TCPSink]
$ns attach-agent $node_(5) $host2
$host2 set mtu_ 1500
$ns connect $host1 $host2
####################################################################
# #
# APPLICATIONS #
# #
####################################################################
set ftp [new Application/FTP]
$ftp attach-agent $host1
$ftp set type FTP
####################################################################
# #
# START SIM #
# #
####################################################################
$ns at 0.1 "$ftp start"
$ns at 10.0 "$ftp stop"
$ns at 11.0 "finish"
$ns run
I want to see the fragmentation of packets, but it is not. What this could be the reason? I suspect that i can not set the
MTU.
Part of data.tr -
Code:
+ 0.1 0 1 tcp 40 ------- 0 0.0 5.0 0 0
- 0.1 0 1 tcp 40 ------- 0 0.0 5.0 0 0
r 0.11016 0 1 tcp 40 ------- 0 0.0 5.0 0 0
+ 0.11016 1 2 tcp 40 ------- 0 0.0 5.0 0 0
- 0.11016 1 2 tcp 40 ------- 0 0.0 5.0 0 0
r 0.12032 1 2 tcp 40 ------- 0 0.0 5.0 0 0
+ 0.12032 2 3 tcp 40 ------- 0 0.0 5.0 0 0
- 0.12032 2 3 tcp 40 ------- 0 0.0 5.0 0 0
r 0.13048 2 3 tcp 40 ------- 0 0.0 5.0 0 0
+ 0.13048 3 4 tcp 40 ------- 0 0.0 5.0 0 0
- 0.13048 3 4 tcp 40 ------- 0 0.0 5.0 0 0
r 0.14064 3 4 tcp 40 ------- 0 0.0 5.0 0 0
+ 0.14064 4 5 tcp 40 ------- 0 0.0 5.0 0 0
- 0.14064 4 5 tcp 40 ------- 0 0.0 5.0 0 0
r 0.1508 4 5 tcp 40 ------- 0 0.0 5.0 0 0
+ 0.1508 5 4 ack 40 ------- 0 5.0 0.0 0 1
- 0.1508 5 4 ack 40 ------- 0 5.0 0.0 0 1
r 0.16096 5 4 ack 40 ------- 0 5.0 0.0 0 1
+ 0.16096 4 3 ack 40 ------- 0 5.0 0.0 0 1
- 0.16096 4 3 ack 40 ------- 0 5.0 0.0 0 1
r 0.17112 4 3 ack 40 ------- 0 5.0 0.0 0 1
+ 0.17112 3 2 ack 40 ------- 0 5.0 0.0 0 1
- 0.17112 3 2 ack 40 ------- 0 5.0 0.0 0 1
r 0.18128 3 2 ack 40 ------- 0 5.0 0.0 0 1
+ 0.18128 2 1 ack 40 ------- 0 5.0 0.0 0 1
- 0.18128 2 1 ack 40 ------- 0 5.0 0.0 0 1
r 0.19144 2 1 ack 40 ------- 0 5.0 0.0 0 1
+ 0.19144 1 0 ack 40 ------- 0 5.0 0.0 0 1
- 0.19144 1 0 ack 40 ------- 0 5.0 0.0 0 1
r 0.2016 1 0 ack 40 ------- 0 5.0 0.0 0 1
+ 0.2016 0 1 tcp 1040 ------- 0 0.0 5.0 1 2
- 0.2016 0 1 tcp 1040 ------- 0 0.0 5.0 1 2
+ 0.2016 0 1 tcp 1040 ------- 0 0.0 5.0 2 3
- 0.20576 0 1 tcp 1040 ------- 0 0.0 5.0 2 3
r 0.21576 0 1 tcp 1040 ------- 0 0.0 5.0 1 2
+ 0.21576 1 2 tcp 1040 ------- 0 0.0 5.0 1 2
- 0.21576 1 2 tcp 1040 ------- 0 0.0 5.0 1 2
r 0.21992 0 1 tcp 1040 ------- 0 0.0 5.0 2 3
+ 0.21992 1 2 tcp 1040 ------- 0 0.0 5.0 2 3
- 0.21992 1 2 tcp 1040 ------- 0 0.0 5.0 2 3
r 0.22992 1 2 tcp 1040 ------- 0 0.0 5.0 1 2
+ 0.22992 2 3 tcp 1040 ------- 0 0.0 5.0 1 2
- 0.22992 2 3 tcp 1040 ------- 0 0.0 5.0 1 2
r 0.23408 1 2 tcp 1040 ------- 0 0.0 5.0 2 3
+ 0.23408 2 3 tcp 1040 ------- 0 0.0 5.0 2 3
- 0.23408 2 3 tcp 1040 ------- 0 0.0 5.0 2 3
r 0.24408 2 3 tcp 1040 ------- 0 0.0 5.0 1 2
+ 0.24408 3 4 tcp 1040 ------- 0 0.0 5.0 1 2
- 0.24408 3 4 tcp 1040 ------- 0 0.0 5.0 1 2
r 0.24824 2 3 tcp 1040 ------- 0 0.0 5.0 2 3
+ 0.24824 3 4 tcp 1040 ------- 0 0.0 5.0 2 3
- 0.24824 3 4 tcp 1040 ------- 0 0.0 5.0 2 3
r 0.25824 3 4 tcp 1040 ------- 0 0.0 5.0 1 2
+ 0.25824 4 5 tcp 1040 ------- 0 0.0 5.0 1 2
- 0.25824 4 5 tcp 1040 ------- 0 0.0 5.0 1 2
r 0.2624 3 4 tcp 1040 ------- 0 0.0 5.0 2 3
+ 0.2624 4 5 tcp 1040 ------- 0 0.0 5.0 2 3
- 0.2624 4 5 tcp 1040 ------- 0 0.0 5.0 2 3
r 0.2724 4 5 tcp 1040 ------- 0 0.0 5.0 1 2
+ 0.2724 5 4 ack 40 ------- 0 5.0 0.0 1 4
- 0.2724 5 4 ack 40 ------- 0 5.0 0.0 1 4
r 0.27656 4 5 tcp 1040 ------- 0 0.0 5.0 2 3
...
How to simulate the fragmentation? I would be very grateful for the information.