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

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

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

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

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 2 8 15 Splits into 2 levels, first level and second level are 8 and 15 bits, respectively

Topology Generator – GT-ITM

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。

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)

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

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

GT-ITM (2/2) Usage: ns nam_show.tcl nam out.nam set ns [new Simulator] ts200.script ts 10 47 4 0 0 1 20 3 1.0 8 20 3 0.8 6 10 3 0.5 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