Chapter 15 The Addressing Structure in NS

1. Chapter 15The Addressing Structure in NS

2. The Default Address Format • 32 lower bits for port-id, 1 higher bit for mcast and the rest 32 higher bits for node-id. • $ns set-address-format def

3. The Hierarchical Address Format • Default Hierarchical Setting • $ns set-address-format hierarchical • 3 levels of hierarchy • Specific Hierarchical Setting • $ns set-address-format hierarchical 2 8 15

4. The Expanded Node-Address Format • address space to 30 bits, allocating 22 higher bits to node-id and lower 8 bits to port-id. • this command is now obsolete given that node address and port address spaces are 32 bits wide.

5. Errors in setting address format • if number of bits specified is less than 0. • if bit positions clash (contiguous number of requested free bits not found). • if total number of bits exceed MAXADDRSIZE_. • if expand-port-field-bits is attempted with portbits less than or equal to the existing portsize. • if number of hierarchy levels do not match with number of bits specified (for each level).

6. Hierarchical Address Format-ex • - • set ns [new Simulator] • $ns set-address-format hierarchical • - • AddParams set domain_num_ 區域數 • AddParams set cluster_num_ 群組數 • AddParams set nodes_num_ 節點數 • design topology

7. Chapter 16Mobile Networking in ns

8. Mobile Networking • Mobile node • Routing mechanisms • Network components • Channel • Network interface • Radio propagation model • MAC protocols • Interface Queue • Link Layer • ARP

9. The basic wireless model in ns • MobileNode object is a split object. • The C++ class MobileNode is derived from parent class Node. (ref ch5) • Difference • added functionalities of a wireless • mobile node like ability to move within a given topology • not connected by means of Links to other nodes or mobilenodes. • Routing mechanisms

10. Implemented in C++ The mobility features node movement periodic position updates maintaining topology boundary etc implemented in Otcl MobileNode itself Classifiers Dmux LL Mac Channel etc Mobilenode Object

13. Creating Node movements • Start position: • $node set X_ <x1> • $node set Y_ <y1> • $node set Z_ <z1> • Future destinations: • $ns at $time $node setdest <x2> <y2> <speed> • Ex: • ns at 3.0 "$node (0) setdest 48.0 38.0 5.0 • the third dimension (Z) is not used.

14. Creating Node movements • random movement • $mobilenode start • Set topology • set topo [new Topography] • $topo load_flatgrid $opt(x) $opt(y) • opt(x) and opt(y) are the boundaries used in simulation

15. Network Components in a mobilenode • MobileNode method add-interface() in ~ns/tcl/lib/ns-mobilenode.tcl

16. MN components • Link Layer-(ref.14) • ARP module connected to it which resolves all IP to hardware (Mac) address conversions • ARP • O-writes it into the mac header of the packet • X-broadcasts an ARP query • Interface Queue • priority to routing rotocol packets • Mac Layer • carrier sense

17. MN components-cont. • Tap Agents • defined in mac.h • register themselves with the mac object using method installTap() • Network Interfaces • mobilenode to access the channel. • implemented Phy/WirelessPhy • Radio Propagation Model • Friss-space attenuation (1/r2) • Two ray Ground (1/r4) • Antenna

18. MAC layer protocols • 802.11MAC protocol • See ~ns/mac-802_11.{cc,h} for implementation details. • Preamble based TDMA protocol • ns supports a single hop, preamble-based TDMA MAC protocol • multi-hop environment are not considered • TDMA frame contains • preamble • data transmission slots • avoid unnecessary power consumption • set_node_sleep().

19. Routing Agents • DSDV • messages are exchanged between neighbouring mobilenodes • ~ns/dsdv directory and ~ns/tcl/mobility/dsdv.tc • DSR • checks every data packet for source-route information. • X-Routing queries • ~ns/tcl/mobility/dsr.tcl • TORA • ns/tora directory and ns/tcl/mobility/tora.tcl • AODV • ns/aodv and ns/tcl/lib/ns-lib.tcl

20. Trace Support • cmu-trace objects are of three types • CMUTrace/Drop • CMUTrace/Recv • CMUTrace/Send • ~ns/trace.{cc,h} and ~ns/tcl/lib/ns-cmutrace.tcl. • tracing all packets that are sent out in a router • set sndT [cmu-trace Send "RTR" $self]

21. Example for wireless • Default Script Options • Main Program • produce some simple node movements • simulation ends

22. Trace Support-cont. • The cmu-trace object CMUTrace is derived from the base class Trace. • See Chapter 26 for details on class Trace • tracing packets • dropped, received and sent by agents, routers, mac layers or interface queues in ns. • All traces are written to the buffer wrk_.

23. Trace Support-cont. • An example of a trace for a tcp packet is as follows: r 160.093884945 _6_ RTR --- 5 tcp 1492 [a2 4 6 800] ------- [65536:0 16777984:0 31 16777984] [1 0] 2 0

24. Revised format for wireless traces • cmu-trace objects • This command should be called before the universal trace command • $ns trace-all <trace-fd> • Currently this new trace support is available for wireless

25. new trace format

26. new trace format • Event type • In the traces above, the first field (as in the older trace format) describes the type of event taking place at the node and can be one of the four types: • s send • r receive • d drop • f forward

27. new trace format • General tag • The second field starting with "-t" may stand for time or global setting • -t time • -t * (global setting)

28. 抽考- Hierarchical Address

29. 抽考-moblie node move