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FLSM and VLSM – Part 1

After many requests to extend the Subnetting Mastery video series, I am adding an appendix which will cover Fixed Length Subnet Masks (FLSM) and Variable Length Subnet Masks (VLSM). This is Part 1, which teaches how to answer questions of this variety: If you start with a /18, what size sub-network would you need to […]

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Voice VLAN – Auxiliary VLAN

The terms Voice VLAN or Auxiliary VLAN typically mean the same thing: They are a feature which allows an access port — which normally only accepts untagged traffic for a single VLAN — to also accept tagged traffic for a second VLAN. But that is merely the “what”, and if you were simply looking for […]

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Converged Network

In the early days of Networking, a computer network was meant to carry only data traffic. As time went on, VOIP, or Voice-Over-IP technologies were invented, computer networks had to be designed to also carry Voice traffic. When a single network fabric is carrying both Data traffic and Voice traffic, it is referred to as […]

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What is the Native VLAN?

The Native VLAN is an oft confused concept, though it needn’t be. This video will explain what the Native VLAN is and how it affects traffic on a wire. Summary An Access port (or “untagged port” in the non Cisco world) is a switch port which carries traffic for only one VLAN. A Trunk port […]

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Subnetting Mastery

Lately I’ve been working on a Subnetting Mastery video series. The goal is take someone with little to no exposure to subnetting and make them a subnetting pro. I’m happy to announce that the video series is finally complete! If anyone is working through or trying to learn subnetting, this is the video series for […]

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Cisco ASA NAT – Configuration Guide

This article provides all the information you need to understand and configure NAT on Cisco ASA and Cisco ASA-X Firewalls. There are  four possible methods of address translation, and each were defined in the Network Address Translation article series: Static NAT, Static PAT, Dynamic PAT, Dynamic NAT. This article assumes prior knowledge of each of […]

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Cisco NAT Configuration – IOS Router

In this article, we will illustrate the Cisco NAT configuration on IOS Routers. This is a follow up article to the Network Address Translation article series which thoroughly covered the operation of NAT and answers the questions “What is NAT?” and “How does NAT work?“. There are only four types of network address translation: Static NAT, Static PAT, […]

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VPN with Overlapping Networks

When connecting two sites together using a Virtual Private Network (VPN), a common issue that is encountered is trying to build a VPN with overlapping networks — where both sites happen to use the same Private IP addresses. In such cases, hosts on one side of the VPN tunnel will be unable to communicate with […]