Why you should be using GNS3 and How to start

I have been mentioning the GNS3 for last 2 Networking blog posts and still using Cisco Packet Tracer to show network topologies and Router Configurations. So, I believe the time has finally come to say a few words about GNS3.

After this, I will be able to use GNS3 in some future blog post about networking and not feel bad about it. :)

What is GNS3?

GNS is a shorthand for Graphical Network Simulator. GNS3 allows you the emulation of network hardware on your PC, similar to Windows Virtual PC. Windows Virtual PC enables you to run operating systems inside the virtual environment. You may have heard of Windows XP mode in Windows 7 for example.


Introduction to Routing

As you may or may not know, communication on the Internet uses packets for transmitting data. So, every time your computer communicates with a computer on the Internet, IP packets are used to transmit and receive data.

Your computer by itself can’t deliver the packets all the way to the destination, so it relies on other networking hardware on the way over to do their part. We could say that Routing is a process of selecting the best paths through the network for forwarding packets from source to their destination.

I have to communicate with another computer! But he’s not in the same network as me! What do I do? Send the packets to the my default gateway! He IS in my network and hopefully, he WILL know what to do! :)


Create a simple AJAX based contact form

Let’s return to Web Development Category and create a Simple Contact Form™! But, just to make things interesting we’ll submit the form using AJAX, so the user gets the feedback without the page refresh. Also, let’s log the User Input into Database for later reviewing.

Here’s a screenshot of our form:


Virtual LANs - Introduction and basic operations

„VLANs? That doesn’t sound like a Web Design or Development theme!” And you’re right! From now on, I’m adding Networking to the Blog categories, and VLANs are going to be my first post.

Virtual? LAN?

Of course, we all know what a LAN is. It is a network which connects computers and other devices and is typically located in our home or office building. LAN enables our devices to share data with each other and access each others resources.

So, LANs are cool, but as always, there’s a room for some improvement. Imagine your company has marketing, production and management departments. In a traditional LAN sense you would have to either:


Few quick CSS tips for easy summer reading

Finally the time has come for another Blog entry, cool and breezy, just right for the summer time. We’re going to do some XHTML/CSS Tips and Tricks you may or may not know. Either way it’ll be quick and simple post, just long enough for you to do the coding while enjoying a nice cold beer. :)

1.1. Simple separator using borders

Probably the most used border trick which creates a simple, nice looking content separator for us. HTML:

<div style="padding: 20px; background-color: #6d6e6d;">
    <div class="separator"> </div>

CSS is very simple, goes like this:

.separator {
    font-size: 0;
    line-height: 0;
    border-top: 1px #1f1f1f solid;
    border-bottom: 1px #c5c5c5 solid;

The code gives us a nice looking simple separator for our content:

All that is left to do is to play with border colors for the desider effect (and adjust margins as needed).

1.2. Fast „double border” trick

Two borders on a image using only img tag and no extra div:

<div style="padding: 20px; background-color: #6d6e6d;">
    <img src="golf.jpg" class="double-border" width="600" height="279" alt="Sveti Martin, golf, hotel and wellness" />

The CSS:

.double-border {
    border: 2px solid #595959;
    padding: 1px;
    background-color: #000000;

It’s really very simple. We use the padding and background color to add the extra black border. Together with the background div this gives us nice results: