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Network Fundamentals: Top Picks

Network Fundamentals
A Denial of Service (DoS) attack is a malicious attempt to disrupt the normal functioning of a website, server or network by flooding it with traffic…
Network Fundamentals
A long-long time ago (not long ago in earth time) 100 Mbps was THE technology. 100 Mbps uplinks bundled with ether-channel was the ultimate uplink te…
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
Network hubs were once the primary method of interconnecting network devices to create a local area network (LAN). Hubs were inexpensive, easy to ins…

Featured Subcategories:

Netflow Articles:

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…
Netflow
In this article, we explore the core principles of bandwidth management and examine how modern network monitoring technologies can assist in maintain…
Netflow
SNMP (Simple Network Management Protocol) and Netflow are both popular protocols with admins, prized for their ability to give visibility over the ne…
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…

Network Protocols:

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…
Supernetting & CIDR
This articles build upon our previous pages covering  what is Supernetting (Route Summarization) & How Supernets Work and Supernetting In-De…
Subnetting
So we have covered to some depth the subnetting topic, but there is still much to learn ! We are going to explain here the available subnet masks and…
TCP - UDP Protocol Analysis
This article shows the TCP Header and Segment. We explain where the TCP Header and Segment are located in an Ethernet frame and also briefly view the…
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…
Subnetting
Routing and Communication between subnets is the main topic here. This article analyses communications between subnets. We provide examples on differ…
IP Protocol
This article explains the 'Network-ID' and 'Host-ID' concept found in IP addressing and subnetting. We analyse the structure of IP addresses and netw…
IP Protocol
This article examines the Internet Protocol (IP) and its position within the OSI Model. We take a look at the IP Header and all fields contained with…

STP/ICMP Protocols:

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…
Spanning Tree Protocol (STP)
Spanning Tree Protocol, Rapid STP port costs and port states are an essential part of the STP algorithm that affect how STP decides to forward or blo…
ICMP Protocol
The Internet Control Message Protocol (ICMP), is a very popular protocol and actually part of an Internet Protocol (IP) implementation. Because IP wa…
ICMP Protocol
The 'ICMP Destination unreachable' message is quite interesting, because it doesn't actually contain one message, but infact six! This means that the…

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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
We mentioned that Trunk Links are designed to pass frames (packets) from all VLANs, allowing us to connect multiple switches together and independently co…
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…
VLAN Networks
If you've read our previous article The VLAN Concept - Introduction to VLANs  then you should feel comfortable with terms such as 'VLAN', 'Stati…

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
Link State routing protocols do not view networks in terms of adjacent routers and hop counts, but they build a comprehensive view of the overall network…
Routing
This article explains how OSPF uses Link State Advertisement (LSA) to exchange information about the network topology between routers. When a router recei…
Routing
Hybrid routing protocols are a combination of distance-vector and link-state routing protocols, and are used to provide a more efficient and scalabl…

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
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…
Network Address Translation - NAT
Before we dive into the deep waters of NAT, we need to make sure we understand exactly what NAT does. So let me give you the background of NAT, why it's h…
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…