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Network Fundamentals: Top Picks

Network Fundamentals
In this section we are going to talk about the different ways a firewall can be set up. Depending on your needs, you can have a very simple firewall…
Network Fundamentals
A network is simply a group of two or more Personal Computers linked together. Many types of networks exist, but the most common types of networks ar…
Network Fundamentals
Content switches (also sometimes called application switches) is a class of network device that is becoming increasingly common in medium to large si…
Network Fundamentals
Next-generation firewalls (NGFWs) and DMZ zones are two critical components of network security that work hand in hand to protect an organization's n…

Featured Subcategories:

Netflow Articles:

Netflow
Monitoring network traffic & bandwidth usage via Netflow is mandatory for any type and size network. Gaining visibility into user traffic, applic…
Netflow
In our previous article we explained how a Netflow Analyzer can help you gain visibility into your user traffic, application traffic and data flows w…
Netflow
In this article, we explore the core principles of bandwidth management and examine how modern network monitoring technologies can assist in maintain…
Netflow
This article will cover the basics of Netflow, including its use cases, Netflow supported devices, Netflow history, and variants. We’ll also dive int…

Network Protocols:

TCP - UDP Protocol Analysis
Our fifth section contains some very interesting fields that are used by the TCP transport protocol. We see how TCP helps control how much data is tr…
Domain Name System (DNS)
The previous article covered the DNS Query message formats. In the article we analysed them in great detail and showed how various options are select…
TCP - UDP Protocol Analysis
Understanding how each protocol fits into the OSI Model is essential for any network engineer. This page analyses how TCP is classified as a 'transpo…
TCP - UDP Protocol Analysis
The third field under close examination is the TCP Header length. There really isn't that much to say about the Header length other than to explain w…
TCP - UDP Protocol Analysis
Finally, the last page of our incredible TCP Analysis. As most of you would expect, this section is dedicated to the DATA section that follows the TC…
TCP - UDP Protocol Analysis
The TCP Options (MSS, Window Scaling, Selective Acknowledgements, Timestamps, Nop) are located at the end of the TCP Header which is also why they ar…
Subnetting
Routing and Communication between subnets is the main topic here. This article analyses communications between subnets. We provide examples on differ…
Domain Name System (DNS)
This section will deal with the analysis of the DNS packets by examining how DNS messages are formatted and the options and variables they contain. T…

STP/ICMP Protocols:

Spanning Tree Protocol (STP)
In this article we will examine the Spanning Tree Bridge ID structure, explain why it has increments of 4096, how VLAN information is embedded (for P…
Spanning Tree Protocol (STP)
One of the most used terms in network is LAN (Local Area Network). It’s a form of network that we encounter in our daily lives, at home, at work, stu…
ICMP Protocol
As mentioned in the previous page, an Echo is simply what we networking engineers call a 'ping'. The Echo Reply is, as most would guess,  the 'p…
ICMP Protocol
The ICMP - Redirect Message is always sent from a gateway to the host and the example below will illustrate when this is used. Putting it simply (be…

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VLAN Networks
Deciding whether to use ISL or IEEE 802.1q to power your trunk links can be quite confusing if you cannot identify the advantages and disadvantages of eac…
VLAN Networks
This article deals with the popular topic of InterVLAN routing, which is used to allow routing & communication between VLAN networks. Our article anal…
VLAN Networks
VLANs are usually created by the network administrator, assigning each port of every switch to a VLAN. Depending on the network infrastructure and securit…
VLAN Networks
We hear about them everywhere, vendors around the world are constantly trying to push them into every type of network and as a result, the Local Area Netw…

Routing
IGRP (Interior Gateway Routing Protocol) is a Cisco proprietary distance-vector routing protocol used in enterprise networks to exchange routing informati…
Routing
This article covers basic OSPF concepts and operation. We explain how OSPF works, how OSPF tables are built on an OSPF-enabled router and their purpose (N…
Routing
We are going to analyse what happens when routing occurs on a network (IP routing process). When I was new to the networking area, I thought that all you…
Routing
Distance Vector, Link State RIP, IGRP, EIGRP, OSPF Routing protocols were created for routers. These protocols have been designed to allow the exchange…

Network Address Translation - NAT
Our previous article, Dynamic NAT - Part 1, covered the basic idea of Dynamic Network Address Translation. We are now going to take a closer look at the p…
Network Address Translation - NAT
The previous page (Static NAT - Part 1) helped us understand what exactly happens with Static NAT and how it works, and we saw a few examples of how to us…
Network Address Translation - NAT
In our previous article, Network Address Translation (NAT) Overload - Part 1, we explained what NAT Overload is and how it works. This page deals with the…
Network Address Translation - NAT
NAT Overload is the most common NAT method used throughout all networks that connect to the Internet. This is because of the way it functions and the limi…