NS Fundamentals (contd..)

1
NS Fundamentals (contd..)

• Padma Haldar
• USC/ISI

2
Outline

• Ns fundamentals Part I (by Chen)
• NS fundamentals Part II
• NS Internals

3
Ns Internals

• Tcl commands translates into
• series of object creation
• plumbing of these objects
• Step-by-step review of how each network component
  gets set up in ns

4
Network Topology Node
Unicast Node
0
0
1
Set ns_ new Simulator multicast on Set n1 ns_
node
set n0 ns_ node
5
Node Addressing

• Two basic address styles available flat and
  hierarchical
• Default flat address 32 bits each for node and
  port id
• Default hier address
• 3 levels of hierarchy
• 10 11 11 or 1 9 11 11 if mcast specified
• Different bit allocation possible for specific
  hier addresses

6
Hierarchical Node
n2
Address classifier
To Port demux
Node entry
Level 3
Level 2
Level 1
ns_ node-config addressing hier
7
Network Topology Link
ns_ duplex-link n0 n1 5Mb 2ms drop-tail
8
Transport
n0
n1
Port Classifier
Port Classifier
Addr Classifier
Addr Classifier
0
0
0
1
dmux_
dmux_
entry_
entry_
classifier_
classifier_
set tcp new Agent/TCP ns_ attach-agent n0 tcp
set tcpsink new Agent/TCPSink ns_ attach-agent
n1 tcpsink
ns_ connect tcp tcpsink
9
Application Traffic Generator
n0
n1
Port Classifier
Port Classifier
Agent/TCPSink
Addr Classifier
Agent/TCP
Addr Classifier
0
0
agents_
agents_
0
1
dmux_
dmux_
entry_
entry_
classifier_
classifier_
set ftp new Application/FTP ftp attach-agent
tcp ns at 1.2 ftp start
10
Routing
Agent/TCP
0
agents_
11
Routing (cont)
Agent/TCP
Agent/TCP
agents_
Link n0-n1
12
Plumbing Packet Flow
n0
n1
Application/FTP
Port Classifier
Port Classifier
Agent/TCPSink
Addr Classifier
Agent/TCP
Addr Classifier
0
0
Link n0-n1
entry_
entry_
Link n1-n0