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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
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
Measuring network performance has always been a difficult and unclear task, mainly because most engineers and administrators are unsure which approac…

Featured Subcategories:

Netflow Articles:

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…
Netflow
Monitoring network traffic & bandwidth usage via Netflow is mandatory for any type and size network. Gaining visibility into user traffic, applic…
Netflow
In this article, we explore the core principles of bandwidth management and examine how modern network monitoring technologies can assist in maintain…

Network Protocols:

Subnetting
There is always that day when you are called upon to provide a solution to a network problem. The number of problems that can occur in a network are…
Subnetting
When we subnet a network, we basically split it into smaller networks. For example, when a set of IP Addresses is given to a company, e.g 254 they mi…
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…
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…
Supernetting & CIDR
Supernetting is the opposite of of subnetting, and is also known as route aggregation or CIDR (Classless Inter-Domain Routing). Supernetting is a tec…
Supernetting & CIDR
This articles build upon our previous pages covering  what is Supernetting (Route Summarization) & How Supernets Work and Supernetting In-De…
TCP - UDP Protocol Analysis
As previously mentioned on a number of occasions, TCP is one of the two protocols that lives at the Transport layer and is used to carry data from on…
TCP - UDP Protocol Analysis
This page will closely examine the Sequence and Acknowledgement numbers. The very purpose of their existence is related directly to the fact that the…

STP/ICMP Protocols:

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…
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 'ICMP Destination unreachable' message is quite interesting, because it doesn't actually contain one message, but infact six! This means that the…
ICMP Protocol
The ICMP - Source Quench message is one that can be generated by either a gateway or host. You won't see any such message pop up on your workstation…

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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
Designing and building a network is not a simple job. VLANs are no exception to this rule, in fact they require a more sophisticated approach because of t…
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
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
Enhanced Interior Gateway Routing Protocol (EIGRP), similar to IGRP, is a Cisco proprietary routing protocol that is used to exchange routing information…
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
IGRP (Interior Gateway Routing Protocol) is a Cisco proprietary distance-vector routing protocol used in enterprise networks to exchange routing informati…
Routing
Distance Vector routing protocols use frequent broadcasts (255.255.255.255 or FF:FF:FF:FF) of their entire routing table every 30 sec. on all their interf…

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
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
After that simple and informative introduction to the NAT concept, it's time to find out more about how it works and this is where the NAT table comes in…
Network Address Translation - NAT
Dynamic NAT is the second NAT mode we're going to talk about. Dynamic NAT, like Static NAT, is not that common in smaller networks but you'll find it used…