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Network Fundamentals: Top Picks

Network Fundamentals

Next-Gen Firewalls & Topologies. Designing & Bu...

Next-generation firewalls (NGFWs) and DMZ zones are two critical components of network security that work hand in hand to protect an organization's...
Network Fundamentals

Measuring Network Performance: Test Network Thr...

Measuring network performance has always been a difficult and unclear task, mainly because most engineers and administrators are unsure which appro...
Network Fundamentals

The Importance of a Network Analyzer – Packet S...

Network Analyzers, also known as Packet Sniffers, are amongst the most popular network tools found inside any Network Engineer’s toolkit. A Network...
Network Fundamentals

Controlling Broadcasts and Multicasts

The first step in controlling broadcast and multicast traffic is to identify which devices are involved in a broadcast or multicast storm. The foll...

Featured Subcategories:

Netflow Articles:

Netflow

Netflow vs SNMP. Two Different Approaches to Ne...

SNMP (Simple Network Management Protocol) and Netflow are both popular protocols with admins, prized for their ability to give visibility over the ...
Netflow

Complete Guide to Netflow: How Netflow & its Co...

This article will cover the basics of Netflow, including its use cases, Netflow supported devices, Netflow history, and variants. We’ll also dive i...
Netflow

NetFlow Analyzer: Free Download, Step-by-Step I...

In our previous article we explained how a Netflow Analyzer can help you gain visibility into your user traffic, application traffic and data flows...
Netflow

Netflow: Monitor Bandwidth & Network Utilizatio...

Monitoring network traffic & bandwidth usage via Netflow is mandatory for any type and size network. Gaining visibility into user traffic, appl...

Network Protocols:

TCP - UDP Protocol Analysis

Transmission Control Protocol - Part 3: The TCP...

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 t...
Domain Name System (DNS)

The DNS Protocol - Part 4: DNS Response Message...

The previous article covered the DNS Query message formats. In the article we analysed them in great detail and showed how various options are sele...
Supernetting & CIDR

The Supernetting / CIDR Chart

This articles build upon our previous pages covering  what is Supernetting (Route Summarization) & How Supernets Work and Supernetting In-...
TCP - UDP Protocol Analysis

UDP Protocol - Header

This article covers the UDP protocol. We examine the structure of the UDP header, the protocols that use UDP as a transport plus a lot more. Some ...
Domain Name System (DNS)

The DNS Protocol - Part 1: Introduction

If you ever wondered where DNS came from, this is your chance to find out ! The quick summary on DNS's history will also help you understand why DN...
TCP - UDP Protocol Analysis

TCP Header Anaylsis - Section 3: TCP Header Len...

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...
TCP - UDP Protocol Analysis

Transmission Control Protocol - Part 4: In-Dept...

This article is an introduction to the 7-page TCP Header analysis section that follows. We briefly view each section of the TCP Header and then mov...
Subnetting

IP Subnetting - Part 3: Subnet Mask Bits & Anal...

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 a...

STP/ICMP Protocols:

Spanning Tree Protocol (STP)

Spanning Tree Protocol – Part 1: Understand 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, s...
ICMP Protocol

ICMP Protocol - Part 1: Introduction

The Internet Control Message Protocol (ICMP), is a very popular protocol and actually part of an Internet Protocol (IP) implementation. Because IP ...
ICMP Protocol

ICMP Protocol - Part 4: Destination Unreachable...

The 'ICMP Destination unreachable' message is quite interesting, because it doesn't actually contain one message, but infact six! This means that t...
ICMP Protocol

ICMP Protocol - Part 2: Echo / Echo Reply (Ping...

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 ...

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VLAN Networks

VTP Pruning

VTP (VLAN Trunking Protocol) pruning is a feature that is used in Cisco switches to reduce unnecessary traffic in VLAN (Virtual Local Area Network) trun...
VLAN Networks

VTP Introduction & Modes

The invention of VLANs was very much welcomed by all engineers and administrators, allowing them to extend, redesign and segment their existing network ...
VLAN Networks

InterVLAN Routing - Routing between VLAN Networks

This article deals with the popular topic of InterVLAN routing, which is used to allow routing & communication between VLAN networks. Our article an...
VLAN Networks

VLANs - IEEE 802.1q Trunk Link Protocol Analysis

While the VLAN Tagging article briefly covered the IEEE 802.1q protocol this article will continue building upon it by further analyzing the IEEE 802.1q...

Routing

OSPF - Part 5: Analysis of OSPF Link State Update (L...

This article explains how OSPF uses Link State Advertisement (LSA) to exchange information about the network topology between routers. When a router rec...
Routing

OSPF - Part 6: OSPF LSA Types - Purpose and Function...

Our previous article explained the purpose of Link State Update (LSU) packets and examined the Link State Advertisement (LSA) information contained with...
Routing

Interior Gateway Protocol - IGRP

IGRP (Interior Gateway Routing Protocol) is a Cisco proprietary distance-vector routing protocol used in enterprise networks to exchange routing informa...
Routing

OSPF - Part 3: OSPF Adjacency & Neighbor Forming Pro...

This is the thrid article of our 6-part OSPF series (see below) that describes how OSPF routers perform neighbor relationship and adjacency. We’ll exami...

Network Address Translation - NAT

Static NAT - Part 2

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 ...
Network Address Translation - NAT

Dynamic NAT - Part 2

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...
Network Address Translation - NAT

Dynamic NAT - Part 1

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 us...
Network Address Translation - NAT

Network Address Translation (NAT) Concepts

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...