#packet forwarding

[ns2ultimate]

Packet Forwarding Mechanism in NS2--Main Post

Note: The content in this series is extracted from the book, Introduction to Network Simulator NS2. You may have to read chapters 3, 4, 5, 9, and 10 of the book for better understanding.

Introduction

Packet forwarding is the key mechanism in ANY network simulation. This, in my opinion, is the most important part in learning NS2. I break down this topic into smaller posts to facilitate the understanding:

Packet forwarding

Packet Construction

Packet Destruction

Prerequisite: NsObject--A packet forwarder in NS2. 

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T. Issaraiyakul and E. Hossain, “Introduction to Network Simulator NS2”, Springer 2009. Buy it now from Amazon:

   You may also find lecture notes and other resource at the following website:http://www.ece.ubc.ca/~teerawat/NS2.htm

[ns2ultimate]

Basic Packet Forwarding in NS2

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Note: The content in this series is extracted from the book, Introduction to Network Simulator NS2. You may have to read chapters 4, and 5 of the book for better understanding.

What's in this post?

In this post, I will show you how packets are forwarded in NS2. This is a very fundamental and is one of the most important concept in NS2.

Preliminaries

This post relies heavily on the concept of Network Objects or NsObjects. You can read this link to for the background. 

Basic Packet Forwarding in NS2

View more presentations from Teerawat Issariyakul.

------------- Related Codes --------------

Packet reception function of class NsObject

class NsObject : public TclObject,public Handler { public: NsObject(); virtual void recv(Packet*,Handler*)=0; }

Example use of packet reception function: Classes Connector and DropTail

void Connector::drop(Packet* p){ if (drop_ != 0) drop_->recv(p); else Packet::free(p); }

void Queue::recv(Packet* p, Handler*) { double now = Scheduler::instance().clock(); enque(p); if (!blocked_) { p = deque(); if (p != 0) { blocked_ = 1; target_->recv(p, &qh_); } } }

======================================================

T. Issaraiyakul and E. Hossain, “Introduction to Network Simulator NS2”, Springer 2009. Buy it now from Amazon:

   You may also find lecture notes and other resource at the following website:http://www.ece.ubc.ca/~teerawat/NS2.htm