1. The Addressing Structure in NS
2010/09/25
Tsai, Wu-Hong
The Addressing Structure in NS

2. Overview (1/2) Address Length Two Parts of Address Space
Thought of a contiguous field of n bits
DEFADDRSIZE_ : 32
MAXADDRSIZE_ : 32
~ns/tcl/lib/ns-default.tcl
Two Parts of Address Space
node-id : higher bits of node-addr or id
port-id : remaining lower bits, port-id or identification of agent attached to the node

3. Overview (2/2) Multicast Address Format ~ns/tcl/lib/ns-address.tcl
Of the higher bits, 1 bit is assigned for multicast.
Address Space
32 bits for node id and 32 bits for port id, also
~ns/tcl/lib/ns-address.tcl

4. Flat Address Format Two Categories of Address Format
Flat – default
Hierarchical – multiple levels
set ns [new Simulator]
$ns set-address-format def

5. Hierarchical Address Format
Default levels, 3 levels – (10, 11, 11) bits
(9, 11, 11) bits for multicast
$ns set-address-format hierarchical
Specific hierarchical setting
For example:
$ns set-address-format hierarchical
Splits into 2 levels, first level and second level are 8 and 15 bits, respectively

6. Topology Generator – GT-ITM

7. Introduction (1/3) Topology Categories
Regular topology – such as ring and star
Well-known topology – ARPAnet, NSFnet
Random topology
由於不同的拓撲結構對網路協定的性能和 適應性有著不同的影響，因此，研究網路 拓樸結構是網路研究的重要基礎和組成部 分。

8. Introduction (2/3) B. M. Waxman – Waxman model (Type I)
u, v : nodes in plane
P(u, v) : the probability that there is an edge connecting node u and v
d : the Euclidean distance between node u and v
L : the maximum distance between any node pairs in the plane
α, β : the random parameters,
α increased  number of edges increased
β ↑  the ratio ↑ (# of long edges : # of short edges)

9. Introduction (3/3) M. Doar & I. Leslie – Doar-Leslie model
E. Zegura, K. Calvert & S. Bhattacharjee – Exponential model

10. GT-ITM (1/2) Files: ~ns/tcl/ex/topo-gen.tcl ~ns/tcl/ex/topo-view.tcl
Example:
~ns/tcl/ex/topo-gen-script.tcl

11. GT-ITM (2/2) Usage: ns nam_show.tcl nam out.nam set ns [new Simulator]
ts200.script
ts 10 47
4 0 0
itm ts200.script
sgb2ns ts200.script-0.gb
set ns [new Simulator]
set nf [open out.nam w]
$ns namtrace-all $nf
 source ts200.tcl
create-topology ns node 1.5Mb
 $ns run
ns nam_show.tcl
nam out.nam