Part II: Part II: NSNS22 Components and ImplementationComponents and Implementation

Part II: Part II: NSNS22 Components and ImplementationComponents and ImplementationNSNS2 2 Components and ImplementationComponents and ImplementationNSNS2 2 Components and ImplementationComponents and Implementation

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Part II: Outline• Nodes and Links• Packets and TimersPackets and Timers• Agents and Applications• Tracing and Debugging

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Part II: OverviewPart II: OverviewApplication

Source Agent Sink Agent

packetn0 n1

packet

Link: Connecting Nodes

Buffer ManagementAgent:

Packet Creation and

Node: A computer host +

A

Buffer ManagementDestruction

Application: Demand Indication

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NodesNodesNodesNodesNodesNodesNodesNodes

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Outline• Overview

Classifier• Classifier• Summaryy

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OverviewOverview• Node functionality

R t– Router – Computer Hosts

• Socket = Address ( Layer 3 ) + Port ( Layer 4 )Socket Address ( Layer 3 ) Port ( Layer 4 )• Select the next hop object based on

– Address ( Router ) FTP CBR– Port ( Computer host )

FTP CBR

source

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Node Architecture

N b h h N b

Node Architecture

• An NsObject which connects an NsObject to– Another NsObject = ( )– More than one NsObject = Classifier

Connector

• Router � Address classifier• Computer host� Port classifierComputer host � Port classifier• Internal mechanism�C / / d h�C++: ~ns/common/node.cc,h

• Route/Port configuration

Textbook: T. Issariyakul and E. Hossain, Introduction to Network Simulator NS2, Springer 2008. 7

� OTcl: ~ns/tcl/lib/ns-node.tcl

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Node Architecture• A composite object

• OTcl domain• OTcl domain– entry_ = Connector – classifier = Address classifier

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classifier_ = Address classifier – dmux_ = Port classifier

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Node: Instvars

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Node: Instprocsp

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Node: Instprocsp

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Node: Instprocsp

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Node: Instprocsp

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Outline• Overview

Classifier• Classifier• Summaryy

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Classifiers: Internal Mechanism (C++)

C• Connector– A single-target packet forwarderg g p– FW received packets to the attached

NsObject (target_)j g• Classifier

– A multi-target packet forwarderA multi target packet forwarder– Examine packet header and classify the

packetpacket– FW packets in the same category to the

same NsObject

Textbook: T. Issariyakul and E. Hossain, Introduction to Network Simulator NS2, Springer 2008. 15

same NsObject.

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Cl ifi E lClassifiers: Examples• Address Classifier• Address Classifier

– Classify packets based on the address• Port Classifier• Port Classifier

– Classify packet based on portFTP CBR

FTP CBR

P t 1 sourcePort 2

Port 1

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destination

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Classifiers: C++ ImplementationClassifiers: C++ Implementation• Purpose: Internal mechanismPurpose: Internal mechanism• Concept:

1 L k t k t h d1. Look at packet header2. FW pkts with the same categories to

th s NsObj t i th s “sl t”the same NsObject in the same “slot”• C++ Implementation: Class Classifier

slot 1

s 2…

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Classifiers: C++ ImplementationClassifiers: C++ Implementation

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Classifiers: C++ ImplementationClassifiers: C++ Implementation• C++ Implementation:C Implementation:

– Variables: • slot : Contain NsObjectslot_: Contain NsObject • default_target_: For packets which does

not match any criteriony– Functions:

• recv(p,h): Receive packets(p, ) p• classify(p): Return the slot number which

matches with the packet header• find(p): Return an NsObject installed in

the slot corresponding to p• install(slot NsObject*): Put the NsObject

Textbook: T. Issariyakul and E. Hossain, Introduction to Network Simulator NS2, Springer 2008. 19

• install(slot,NsObject*): Put the NsObject in the slot “slot”pa

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rednd(p):the sloins

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l fClassifiers::install(slot,NsObject*)• Put “p” in slot [slot]Put p in slot_[slot]

pinstall NsObject

slot_ … …1 2 slot

Textbook: T. Issariyakul and E. Hossain, Introduction to Network Simulator NS2, Springer 2008. 20

Classifier

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Classifiers::find(p)Classifiers::find(p)• Return an NsObject* corresponding j p g

to packet “p” Function classify(p) is defined in fthe derived class

findp

slot_ … …1 2 cl

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Classifier

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Classifiers::Classify(p)

• Return the “slot number” corresponding to packet “p”

• Defined in the derived class• Defined in the derived class– HashClassifier– PortClassifier

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Classifiers::recv(p h)• recv(p,h)

Classifiers::recv(p,h)(p, )

1. Located NsObject for packet “p” using “find(p)”find(p)

2. Forward the packet to the located NsObjectNsObject

(1)

(2)

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Classifiers: OTcl Implementation

• Purpose: Configure a classifier � P t N Obj t i th l t� Put NsObjects in the slots� Retrieve NsObjects� Retrieve NsObjects

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Cl ifi R CClassifiers: ReCap

• Classifier is a multi-target packet g pforwarder

• Used as• Used as– Router (AddressClassifier)– Host (PortClassifier)

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Classifiers: The Simulation• At the Network Configuration phase

D fi l ifi ti it i– Define classification criterion– Configure (put NsObject in slots)

di laccordingly• At the Simulation phase

– Receive packet: recv(p,h)� “classify” the packet py p p�forward the packet the matched NsObject

Textbook: T. Issariyakul and E. Hossain, Introduction to Network Simulator NS2, Springer 2008. 26

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Classifiers: Inheritance Concept

• Function classify(p) is to beFunction classify(p) is to be overridden by the derive classA E l• An Example– Port Classifier– C++ Class PortClassifier

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Classifiers: Inheritance ConceptClassifiers: Inheritance Concept

• Network Configuration Phase:• Network Configuration Phase:( $ns attach-agent $n0 $udp )

• Simulation Phase:• Simulation Phase:

Destination port number agent

slot_ … …1 2 tClassifier

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1 2 portClassifier

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Classifiers: Other Configuration gprocedures

C t d i t l ifi• Create and register classifiers– $ns node – Node::initNode init– Node::mk-default-classifier

R fi i• Route configuration– NS2 runs Dikjstra algorithm for all pairs of nodes– $ns run$ns run– RouteLogic::configure

• Agent attachment – $ns attach-agent $node $agent– Node::attach

Textbook: T. Issariyakul and E. Hossain, Introduction to Network Simulator NS2, Springer 2008. 29

– Node::attach

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Summary• Node Functionality

( Router ) and ( Computer Host )– ( Router ) and ( Computer Host )– Consists of connectors and classifiers

• Classifiers– Multi-target connectorMulti target connector– Router � ( Address classifier )

C t h t� ( P t l ifi )– Computer host � ( Port classifier )

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Related Files/ / d h• ~ns/common/node.h,cc

• ~ns/common/simulator.h,cc• ~ns/routing/route.h,cc

/ /• ~ns/routing/rtmodule.h,cc• ~ns/classifier/classifier.h,cc• ~ns/classifier/classifier-hash.h,cc • ~ns/classifier/classifier-port.h,cc• ~ns/tcl/lib/ns-lib.tcl• ~ns/tcl/lib/ns-node.tclns/tcl/lib/ns node.tcl • ~ns/tcl/lib/ns-route.tcl• ~ns/tcl/lib/ns-rtmodule.tcl

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