Articles
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Articles:
The OSI Model: Layer 5 - Session Layer
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Articles:
The OSI Model: Layer 4 - Transport Layer
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Articles:
The OSI Model: Layer 3 - Network Layer
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The OSI Model: Layer 2 - Datalink Layer
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Articles:
The OSI Model: Layer 1 - Physical Layer
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Suggested Articles:
IP Protocol
IP Protocol - Part 3: IP Classes, Network & Host…
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…
Network Protocols
Understanding VPN IPSec Tunnel Mode and IPSec Tra…
IPSec’s protocol objective is to provide security services for IP packets such as encrypting sensitive data, authentication, protection against repla…
Ethernet Protocol, CSMA/CD, Collisions
Late Ethernet Collisions
Late collisions, on the other hand, are not normal and are usually the result of out of spec. cabling or a malfunctioning adapter. A late collision i…
ICMP Protocol
ICMP Protocol - Part 4: Destination Unreachable M…
The 'ICMP Destination unreachable' message is quite interesting, because it doesn't actually contain one message, but infact six! This means that the…
Featured Subcategories:
Netflow Articles:
Netflow: Monitor Bandwidth & Network Utilization…
Monitoring network traffic & bandwidth usage via Netflow is mandatory for any type and size network. Gaining visibility into user traffic, applic…
Complete Guide to Netflow: How Netflow & its Comp…
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 vs SNMP. Two Different Approaches to Netw…
SNMP (Simple Network Management Protocol) and Netflow are both popular protocols with admins, prized for their ability to give visibility over the ne…
NetFlow Analyzer: Free Download, Step-by-Step Ins…
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…
Wi-Fi Key Generator
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VLAN Networks
VTP Protocol - In-Depth Analysis
The previous article introduced the VTP protocol, we examined how it can be used within a network, to help manage VLANs and ease the administrative overhe…
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 anal…
VLAN Networks
VLANs - Access & Trunk Links
If you've read our previous article The VLAN Concept - Introduction to VLANs then you should feel comfortable with terms such as 'VLAN', 'Stati…
VLAN Networks
Comparing Traditional Flat & 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…
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 informati…
Routing
OSPF - Part 4: OSPF Neighbor States – OSPF Neighbor Fo…
This is the third article of our OSPF series which analyzes the different OSPF States routers go through during the OSPF discovery and neighbor forming pr…
Routing
Routed Protocols
We all understand that TCP/IP, IPX-SPX are protocols which are used in a Local Area Network (LAN) so computers can communicate between with each other and…
Routing
Routing Information Protocol - RIP
Routing Information Protocol (RIP) is a distance-vector routing protocol that is commonly used in small to medium-sized networks. It is one of the o…
Cisco Switches
Cisco 4507R+E Layer 3 Installation: Redundant WS-X45-S…
It's no news that we here at Firewall.cx enjoy writing about our installations of Cisco equipment and especially devices that we don’t get to see and play…
Cisco Routers
How to Capture Packets on your Cisco Router with Embed…
If you’re tired of setting up SPAN sessions to capture network traffic transiting your network and Cisco router, it’s time to start using Cisco’s Embedded…
Cisco Firewalls
Converting Cisco Firepower from Platform mode to Appli…
This article explains how to configure a Cisco Firepower 2100 series device to operate in Appliance mode. We’ll show you how to switch from Platform mode…
Cisco Routers
Resolving Cisco Router/Switch Tftp Problems: Source IP…
When working with Cisco equipment that has multiple ip interfaces, a common problem engineers are faced with is trying to successfully tftp to or from the…







