netsim/levels/01 Basics/level03.html

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<h1>Basics Level 3</h1>

<p>So far we have seen very basic packets. These packets have shown only the source (who sent the packet) and the
destination (who received the packet). In this level, we will see a more complex packet that will give the recipient
information about how to respond.

<p>Pause the simulation to view the packet sent from Alice's computer to Google. There is a new header under the
<strong>transport layer</strong>. The header, <strong>proto</strong> defines the <strong>protocol</strong> that will
be run on this layer. The protocol listed is <strong>ICMP</strong>, which refers to a <strong>ping</strong>. When a
computer receives a packet with an ICMP echo request (ping) they respond by sending back a packet with an ICMP echo
(pong). Resume the simulation and notice the packet sent from Google to Alice's computer.

<p>To complete this level, you must send 4 more ICMP echo requests (pings) from Alice to Google. Proceed as before,
by adding a new packet in the Timeline Editor. Remember to add the new <strong>transport layer</strong> header.

<p><em><strong>Hint:</strong> use the 'repeat' feature in the Editor to send the same packet many times!

<h3>Level Objectives</h3>

<ul>
	<li>remember to go to the <strong>next level</strong> in the timeline editor</li>
	<li>send 4 more ping requests to Google</li>
</ul>