Lambda packaging the right way
Simplicity One of the beautiful things about Lambda is its simplicity. You write code, test it and then you deploy it. If it works on your machine, you can ...
Posts by Year
2020
Architecting on AWS: ALB
This post is a part of the “Architecting on AWS” series Picking up from where we left off, we need eliminate the single point(s) of failure in our architect...
Architecting on AWS: EC2
This post is a part of the “Architecting on AWS” series Picking up from where we left off, the the devs’ requirements were as follows: They need a web s...
Architecting on AWS: Infrastructure as Code (IAC)
This post is a part of the “Architecting on AWS” series Today’s the first day at our new job! After meeting the team, we were given our first task: Set up a...
Architecting on AWS series
In a previous post, I stressed the importance of hands on experience when it comes to preparing for AWS exams. However, people often object because “it’s too...
Python: Automating network health checks
I was a network engineer in a previous life. Though I’ve moved into DevOps, my love for network automation has not subsided. Recently, an engineer posted a ...
How I passed the 3 AWS Associate exams in 1 month
Due to COVID social distancing, I’m currently working from home. As I no longer travel to and from the office each day, I figured I’d put my newfound spare t...
Creating automated, infinitely scalable labs on AWS: Part 1
As a senior Sales Engineer for Trend Micro, I regularly run security PoCs, demos, webinars, etc. One day while running one of these sessions, I had an idea: ...
Multithreading with Python and Netmiko
If you ran the script in the previous post, you will have found it took approximately 18 seconds to run. While that may not feel like a lot of time, what if ...
Network Automation with Cisco Modeling Labs (CML2)
Coming from a network engineering background, network automation has always interested me. In fact, it was network automation which spiked my interest in Dev...
Python: Covering all your bases with Coverage
Test Driven Development (TDD) in Python touched on TDD and pytest. Then in Taking pytest for a test drive we dived deeper on both subjects. Now that we’ve g...
Taking pytest for a test drive
In the previous post we got a glimpse of pytest. In this post, we’ll be diving a little deeper. To do this, we’ll be build a basic Flask app. Before we star...
Test Driven Development (TDD) in Python
Have you heard of Test Driven Development (TDD)? If you haven’t, you’re in for a real treat. TDD is a development methodology. Before writing a new function...
Learn Python: Dissecting Netmiko - Part 3
This is the third post in this series. If you missed Part 2, you can find it here. Dissecting platforms Though it appears platforms is only 2 lines: 1 2 p...
Writing clean Python using Black
There are two important methodologies which can be used to assist you in writing clean, maintainable code. They are: Style Guides Test Driven Developmen...
Learn Python: Dissecting Netmiko - Part 2
This is the second post in this series. If you missed Part 1, you can find it here. Dissecting ConnectHandler Let’s continue our ConnectHandler investigati...
Learn Python: Dissecting Netmiko - Part 1
In the not too distant past, I was a network engineer. In fact, it’s my interest in network automation that led me to DevOps, but I digress. During my networ...
2018
Writing a Grafana backend using the Simple JSON datasource & Flask
I’ve used Grafana for several years. Ever since the first time I used it, I have wanted to sit down and write a server which would provide metrics to it thro...
Kubernetes from the Ground Up: Server Components
In the previous post, Choosing a configuration method, we looked at the three ways in which a Kubernetes cluster can be configured. In this post we’ll go thr...
Installing & using Python virtualenv
virtualenv, as the name suggests, creates virtual Python environments. If you’re familiar with server virtualisation, virtualenv acts in a similar fashion to...
CI/CD: Setting up GitLab Runners on AWS using CoreOS & Terraform
GitLab Runner is used as part of GitLab CI/CD pipelines. On a side note, it also supports GitHub and BitBucket too! But I digress… In this post we’ll cover...
Kubernetes from the Ground Up: Choosing a configuration method
In the previous post, What is it?, we gained an understanding of Kubernetes and container orchestrations in general. In this post we’ll cover the three ways ...
Kubernetes from the Ground Up: What is it?
If you’ve looked into containers before, you’ve likely heard the name Kubernetes. This post will tackle what it is at a high level, while subsequent posts wi...
DevOps: The Evolution of Applications
One server per application In the not too distant past, it was normal to have a one to one relationship between applications and servers. For example, your ...
2017
Getting Started with Prometheus - Part 2
As you’ve probably guessed by Docker posts, I’m a huge fan of containerisation. Therefore instead of installing Prometheus on a host, let’s instead spin it u...
Getting Started with Prometheus - Part 1
If you’ve used Grafana, or even heard of it, chances are you’ve also heard of InfluxDB and Prometheus too. As I haven’t touched on the latter yet, I figured ...
Getting Started with Docker - Part 2
In the previous post we may have started running before we could walk. In this post we’ll first take a few steps back to make sure we cover the basics before...
Getting Started with Docker - Part 1
For those new to Docker, you’re probably wondering - What is it exactly? “Docker is the company driving the container movement and the only container platfo...
Git: nano on Windows
When you’re developing on two different OS’ (e.g Windows & Linux), the last thing you want to do is have to remember which tools to use on which system. ...
Python: Demystifying AWS’ Boto3
As the GitHub page says, “Boto3 is the Amazon Web Services (AWS) Software Development Kit (SDK) for Python, which allows Python developers to write software ...
Git: Merging & Rebasing basics
In the Git: Keeping in sync post we learned how to merge the orgin/master commits into our local master branch. Then in Git: Effective branching using workfl...
Git: Keeping in sync
In the Getting start with git post we covered a number of things, one of which was using push to send our commits to a remote git repo. This is works fine wh...
Git: Effective branching using workflows
In the Getting started with git we learned about local and remote branches (master and origin/master respectively), and in Git: Keeping in sync we learned ho...
Getting started with git
What is git? Wikipedia has a great answer for this question: Git is a version control system for tracking changes in computer files and coordinating work o...
Testing your code with pytest
If you’re fairly new to coding chances are you’ve run into an issue where you make a minor change in one place, and then end up breaking your script in anoth...
Allure2: A GUI for your code tests
In my previous post I touched on the basics of how you can use pytest to test your code. In this post I’ll be covering how you can use Allure2 to prettify yo...
Python: Shadowing
In my previous post, Python: Scope, I touched on the topic of Shadowing. In this post I’ll be delving deeper into it. As Wikipedia says, variable shadowing ...
Python: Scope
Scope is the term used to define the location(s) in which Python searches for a name to object mapping (e.g a variable). As described in this StackOverflow ...
Python: Everything is an Object & First Class Citizens
A lot of Python books often mention that “everything in Python is an object”, and “objects are first class citizens”, but they don’t always explain what that...
Python: if name == “main”
There are plenty of articles on the internet that attempt to explain what if name == “main“ is and what it does, but (in my humble opinion), the examples are...
Windows: Accessing Python & pip from anywhere
When you install Python on Windows, you may find that you cannot access it and/or pip from anywhere on the commandline. For example, you find that you need t...
Navigating InfluxDB CLI
I’ve demonstrated a few InfluxDB commands in my Getting to know InfluxDB and InfluxDB: Retention Policies & Shard Groups posts but though it would be a g...
Getting to know Telegraf
I first mentioned Telegraf in the My Monitoring Journey: Cacti, Graphite, Grafana & Chronograf post and then covered its installation and setup in the In...
InfluxDB: Retention Policies & Shard Groups
Note: This is a continuation of the Getting to know InfluxDB post. If you haven’t read it yet, I suggest you do before reading this post. I found InfluxDB’s...
Getting to know InfluxDB
I touched on InfluxDB in the My Monitoring Journey: Cacti, Graphite, Grafana & Chronograf post and then covered its installation and setup in the Install...
Installing & Setting up InfluxDB, Telegraf & Grafana
I mentioned these tools in the My Monitoring Journey: Cacti, Graphite, Grafana & Chronograf post and thought now would be a good time to cover their inst...
My Monitoring Journey: Cacti, Graphite, Grafana & Chronograf
I remember using Cacti at my first job over a decade ago. I’ve revisited it more than a few times since but it hasn’t been my go to monitoring tool for quite...
Interpreted, Bytecode & Just-in-Time
In my previous post I discussed what a compiler does. In this post I will cover Interpreted code, Bytecode and Just-in-Time compilation. One thing to note at...
Understanding Ansible Output Structure
Note that this post uses NTC-Ansible. Installation instructions can be found here. In the Ansible –extra-vars post we saw just how out of control outputs ca...
Looping through Dictionaries in Ansible
Note that this post uses NTC-Ansible. Installation instructions can be found here. In the Understanding Ansible Output Structure post we saw how to extract ...
Cleaning Up Ansible Loop Outputs
Note that this post uses NTC-Ansible. Installation instructions can be found here. As we saw in the –extra-vars post, the first Playbook produces a very cle...
Ansible –extra-vars
Note that this post uses NTC-Ansible. Installation instructions can be found here. Often you will see variables defined in a Playbook, a Task and/or a varia...
Installing Git on Windows
Installing Git on Windows is very similar to installing it on Linux. That might not come as a surprise though because the tools we’ll be using in this post a...
Installing Ansible on Windows
While Ansible is not supported on Windows, it is very easy to get it up and running. The Ansible documentation provides information on how to do it using Wi...
What does a Compiler do?
If you’ve used Linux before and/or have coded using a language such as C, you will have come across a compiler. Though because they’re so easy to use, you mi...
Python: A Strong, Dynamically Typed Language
You’ve probably already heard that Python is a strong, dynamically typed language. But what does that actually mean? Let’s jump in and take a look. Dynamica...
Python: Statements & Expression
In Learning Python (a must read for anyone interested in Python!), author Mark Lutz refers to statements and expressions frequently, but give a clear explana...
Python: The difference between Lists & Tuples
A common misconception is that the only difference between Lists and Tuples is that the former is mutable while the latter is immutable. While this is true, ...
Installing NTC Ansible
I’ve written about NTC-Ansible a couple of times already and thought now would be a good time to run you through the installation process. The github page pr...
Jinja2 Tests Overview
As per the Jinja documentation: Beside “filters“, there are also so-called “tests” available. Tests can be used to test a variable against a common expressi...
Jinja2 selectattr() Filter
As per the documentation: “selectattr() filters a sequence of objects by applying a test to the specified attribute of each object, and only selecting the o...
Jinja2 Overview
There are two ways in which you can use Jinja templates inside of Ansible are: Templates Filters This blog post demonstrates both of these techniques...
Jinja2 map() Filter
Reference: jinja Applies a filter on a sequence of objects or looks up an attribute. This is useful when dealing with lists of objects but you are really on...
Jinja2 Filter Overview
Reference: Stack Overflow With the pipe character you pass a value to a filter. There are numerous Jinja 2 filters but Ansible brings some additional filter...
Jinja2 equalto() Test
Reference: Jinja Check if an object has the same value as another object. Example As per the selectattr( ) page, the Jinja equalto( ) Test, as well as t...
Jinja2 default() Test
Example #1 Reference: Jinja Syntax: default(value, default_value=u'', boolean=False) Example #1 If the value is undefined it will return the passed def...
Git Local Overwrite
If your local repository is behind that of the remote repository and your locally tracked files differ from those of the remote repository, you will encounte...
Installing Git on Ubuntu
Install git sudo apt-get install git Generating Ubuntu SSH key ssh-keygen Find your SSH key. cd ~/.ss...
Ansible vars Lists
Lists can be provided to a module through vars specified inside a Playbook or they can be provided directly inside a Task. In the examples below we want to ...
Ansible Variables
Using Variables: About Jinja2 Reference: Ansible Ansible allows you to reference variables in your playbooks using the Jinja2 templating system. While you ...
Ansible Variable Persistence
Reference: Stackoverflow set_fact module only sets facts available during a run. For persistent facts, you’ll need to either: Static: define them i...
Ansible set_facts
Reference: Ansible This module allows setting new variables. Variables are set on a host-by-host basis just like facts discovered by the setup module. ...
Ansible search() Test
Reference: Ansible match requires a complete match in the string, while search only requires matching a subset of the string. Example As per the selecta...
Ansible Minimum Viable Playbook (MVP)
Reference: Adam’s Tech Blog The Minimum Viable Playbook (MVP) is the shortest, most useful Ansible playbook I have. Whenever I need to write some Ansible co...
Ansible match() Test
Reference: Ansible match requires a complete match in the string, while search only requires matching a subset of the string. Example As per the selectatt...
Ansible Lists & Dicts Overview
Reference: Ansible All members of a list are lines beginning at the same indentation level starting with a - (a dash and a space): --- # A list of tasty f...
Ansible Inventory
Hostnames Reference: Ansible Variables & Inventory inventory_hostname is the name of the hostname as configured in Ansible’s inventory host file. Thi...
Ansible Installation
Reference: Ansible To configure the PPA on your machine and install Ansible run these commands: $ sudo apt-get install software-properties-common $ sudo ap...
Ansible Conditionals
Inline expressions Reference: Inline ‘if’ expressions It’s possible to use inline if-expressions: {{ 'Update' if files else 'Continue' }} Note: See the...
Ansible Built-in Variables
Ansible has built in variables which you can come in handy with some Playbooks. They can be viewed using the following Ad-Hoc command: ansible all -i 192.16...
Ansible Ad-Hoc Commands
As per the Ansible documentation: An ad-hoc command is something that you might type in to do something really quick, but don’t want to save for later. For...
Use Ansible Tags to Organise your Plays & Tasks
The Ansible tag documentation does a great job of explaining tags, tag re-used and tag inheritance. However, I’d like to dive a little deeper to show you ju...
The Anatomy of an Ansible Playbook
I published my Ansible Playbook Structure post a few months ago. Upon re-reading it recently I felt that it lacked detailed around the components of a playbo...
Interacting with NetApp APIs, Part 3
In Part 2 of this series we made our first API call and received over 200 lines of XML as a result. The reason why we received so much output is because we d...
Interacting with NetApp APIs, Part 2
Picking up where I left off in Part 1 of this series, let’s continue our exploration of ZExplore :) Mandatory Parameters In part 1 I touched on the fact th...
Interacting with NetApp APIs, Part 1
If you’re a regular reader of this blog, you’ll see that I’ve been posting about automation and Python quite a lot recently. The reason being that it’s not o...
Learning Python
In my Why Automate? post I discussed how important I feel automation skills will be for engineers in the near future. I even went as far as to say that those...
2016
Writing your own API, Part 4
Now that we’ve covered how TextFSM work and how it can be used to record useful information from device outputs, it’s time to move our focus on how we use Te...
Why Automate?
As my collection of automation posts continues to grow, now is a good time to discuss why you should use automation. The two automation related comments/que...
Ansible Playbook Structure
Update: If you find this article useful, I suggest reading the Anatomy of an Ansible Playbook post as well. Recently I posted about how it can be easy to ge...
Guide: Building a Self-Contained Ansible & GNS3 Lab
My collection of Ansible posts is steadily rising, so I thought it would be a good idea to write a post on how you can connect an Ansible VM into GNS3 so tha...
Writing your own API, Part 3
In my previous post I covered how to to download, install and test TextFSM. In this post I’ll demonstrate how to write your own template files so that you ca...
Writing your own API, Part 2
As I mentioned in my previous post, NTC-Ansible uses TextFSM templates to allow you to convert your CLI outputs to JSON and then access the data in an API-li...
Writing your own API, Part 1
In this series of posts I will cover how you can create your own API-like functionality for devices which do not have APIs built into them. Before I get star...
Getting started with Ansible
In my previous post, Getting started with Network Automation, I discussed why I chose Ansible as my configuration management and orchestration tool over the ...
Getting started with Network Automation
I’ve been looking into network automation for quite some time now. Originally I started off looking into automating small tasks by writing Python scripts but...
Building a NetApp ONTAP 9 Lab for free!
What better way to start the Zero to Hero Guide than learning how to build your own ONTAP lab for free? Thanks to Neil Anderson over at FlackBox, we can do j...
Subnetting Made Easy, Part 6
Note: As you will soon see I use tables (some might say excessively :P) in this post. I did this is because it closely resembles what a lot of network engine...
2015
The NetApp Zero to Hero Guide - What is RAID?
If you’ve never delved into the server or storage side of the IT industry, there is a chance you might not have heard of RAID before (Redundant Array of Inde...
The NetApp Zero to Hero Guide - Introduction
Just under a year ago I wrote a blog series called NetApp From The Ground Up - A Beginner’s Gude. Since the publication of the series I have been getting e-m...
Finding a Host’s Switchport
In this post I will demonstrate how we can find out which of SW3’s switchports PC1 is connected to in the topology diagram below. To make things more fun tho...
Mastering EIGRP Metric Calculations
To properly administer an EIGRP network an admin really should know how EIGRP calculates and chooses best paths. If you’ve read any CCNA or CCNP resource you...
NetApp Insight is just around the corner!
I thought I’d write up a quick blog post to celebrate the fact that NetApp Insight is around the corner! If you haven’t seen them already you can find my Ne...
Subnetting Made Easy, Part 5
After publishing my previous post, I received another e-mail from the author of the original e-mail: … So basically, I would like to find out how to find th...
Subnetting Made Easy, Part 4
Recently I received the following e-mail from a reader: I have read, and followed your method of finding subnet mask addresses, and calculating the first an...
A Deep Dive in OSPF LSAs, Part 7
So far in this series I’ve covered Type 1, 2 and 3 LSAs. Next I’m going to cover Type 4 and Type 5 LSAs with the help of this topology. Before we get star...
A Deep Dive in OSPF LSAs, Part 6
Up until this point I have only covered Type 1 and Type 2 LSAs in this series. I’m guessing by now you must be quite familiar with them and are interested to...
A Deep Dive in OSPF LSAs, Part 5
In Part 3 I demonstrated how you can use Type 1 and Type 2 LSAs to map the topology an OSPF area. In this post we’ll do the reverse. By looking at a network ...
A Deep Dive in OSPF LSAs, Part 4
As mentioned a couple of times in this series, Type 1 LSAs differ between Broadcast and Point-to-Point segments. To demonstrate this, I’ll be using the same ...
A Deep Dive in OSPF LSAs, Part 3
In my previous post I covered Type 1 and Type 2 LSAs in relation to broadcast networks. In this post I’ll demonstrate how you can use these LSAs to map the t...
A Deep Dive in OSPF LSAs, Part 2
In my previous post I covered the inspiration for this series of posts as well as many of OSPF’s LSAs. Now that we’ve got the boring stuff out of the way, le...
A Deep Dive in OSPF LSAs, Part 1
Configuring an OSPF network can be very easy. Within a couple of commands you can have a fully functioning network. While being easy to configure is definite...
A Deep Dive in OSPF LSAs – Index
Below is a list of all the posts in the “A Deep Dive in OSPF LSAs” series: A Deep Dive in OSPF LSAs, Part 1 A Deep Dive in OSPF LSAs, Part 2 A Deep D...
Cisco UCS From the Ground Up - A Beginner’s Guide Part 5
In my previous post I described how you can achieve 80Gb per blade with a UCS system. I went a little deeper than I had intended, so I thought it would be go...
Cisco UCS From the Ground Up - A Beginner’s Guide Part 4
OK, so in Part 1 and Part 2 I gave high level overviews of the UCS components. In Part 3 I did it all over again, but went a little deeper that time around. ...
Cisco UCS From the Ground Up - A Beginner’s Guide Part 3
In Part 1 & Part 2 I provided a high level overview of the UCS components. In this post I’m going to delve deeper into each of these components as well a...
Cisco UCS From the Ground Up - A Beginner’s Guide Part 2
In my previous post I covered Wikipedia’s and my versions of an overview of the UCS platform. For good measure, here are a couple of additional “Overview” in...
Cisco UCS From the Ground Up - A Beginner’s Guide Part 1
My NetApp From the Ground Up series of posts have proven to be quite popular. Though I still have quite a lot of posts left to write in that series, I though...
Cisco UCS From the Ground Up – A Beginner’s Guide - Index
Below is a list of all the posts in the “Cisco UCS From the Ground Up – A Beginner’s Guide” series: Cisco UCS From the Ground Up – A Beginner’s Guide Par...
NetApp From the Ground Up - A Beginner’s Guide Part 13
Snap Reserve Overview Reference: NetApp - Understanding Snapshot copy reserve Snapshot copy reserve sets a specific percent of the disk space for stori...
NetApp From the Ground Up - A Beginner’s Guide - Index
Below is a list of all the posts in the “NetApp From the Ground Up - A Beginner’s Guide” series: NetApp From the Ground Up - Part 1 NetApp From the Gro...
NetApp From the Ground Up - A Beginner’s Guide Part 12
Volume and Aggregate Reallocation Reference: Understanding NetApp Volume and Aggregate Reallocation Summary Volume Reallocation: Spreads a volume a...
NetApp From the Ground Up - A Beginner’s Guide Part 11
Capacity Right-Sizing Reference: NetApp Forum Disk drives from different manufacturers may differ slightly in size even though they belong to the same ...
Guide: Building a Self-Contained Virtual Steelhead Lab - Part 4
Note: This post carries on from Part 3. Testing & Reporting Now that you’ve set up your lab, you can start working on the VSHs. Test #1 - TCP Options...
Guide: Building a Self-Contained Virtual Steelhead Lab - Part 3
Note: This post carries on from Part 2. Virtual Steelhead Installation Now that the vSwitches are set up, the next thing you will need to do is install the...
NetApp From the Ground Up - A Beginner’s Guide Part 10
OnCommand Overview Reference: NetApp Training - Fast Track 101: NetApp Portfolio OnCommand management software helps your customers to monitor and mana...
Guide: Building a Self-Contained Virtual Steelhead Lab - Part 2
Note: This post carries on from Part 1. VLANs SW1 and SW2 have been used to allow multiple devices to connect to the VSH’s Primary, Auxiliary and lan0_0 su...
Guide: Building a Self-Contained Virtual Steelhead Lab - Part 1
A little while back I began looking into WAN optimisation, and in particular, Riverbed’s Steelheads. I really enjoyed all that I was reading so decided it wa...
Trunking VLANs between the NetApp Simulator and GNS3
In my previous post Connecting the NetApp Simulator to your Virtual and Physical Labs, I explained the steps you need to follow in order to connect the NetAp...
Connecting the NetApp Simulator to your Virtual and Physical Labs
I have written a few pieces on making the most out of your virtual and physical labs. These include: Connecting Your PC to Your Virtual GNS3 Routers Vi...
NetApp From the Ground Up - A Beginner’s Guide Part 9
SnapRestore Reference: NetApp SnapRestore NetApp SnapRestore software uses stored Snapshot copies to recover entire file systems or data volumes in sec...
About Me - Update
Update (January 2015): Well, it has been just over three years since my original “About Me” post and quite a lot has changed. To begin with, I’m no longer 2...
2014
NetApp From the Ground Up - A Beginner’s Guide Part 8
HA Pair Summary Reference: Overview of NetApp Replication and HA features HA Pair is basically two controllers which both have connection to their own...
NetApp From the Ground Up - A Beginner’s Guide Part 7
SyncMirror Summary Reference: Overview of NetApp Replication and HA features SyncMirror mirror aggregates and work on a RAID level. You can configure ...
NetApp From the Ground Up - A Beginner’s Guide Part 6
Backups Reference: NetApp Training - Fast Track 101: NetApp Portfolio Affordable NetApp protection software safeguards your data and business-critical ...
NetApp From the Ground Up - A Beginner’s Guide Part 5
FlexVolume Reference: NetApp University - Introduction to NetApp Products Data production and data protection are the basic capabilities of any storage...
NetApp From the Ground Up - A Beginner’s Guide Part 4
WAFL Reference: Bitpushr: How Data ONTAP caches, assembles and writes data WAFL is our Write Anywhere File Layout. If NVRAM’s role is the most-commonly...
NetApp From the Ground Up - A Beginner’s Guide Part 3
Storage Summary Reference: Me :) Vservers : contain one or more FlexVol volumes, or a single Infinite Volume Volume : is like a partition that can spa...
NetApp From the Ground Up - A Beginner’s Guide Part 2
Overview Source #1 Reference: Datadisk - NetApp Overview The NetApp filer also know as NetApp Fabric-Attached Storage (FAS) is a type of disk storage ...
NetApp From the Ground Up - A Beginner’s Guide Part 1
I have recently started working on a FlexPod environment. The environment relies on NetApp for all of its storage needs, but unfortunately I hadn’t worked wi...
How to Land your Dream Job
I have been very lucky in my career to date. Over the years I have been given the privilege of working in some great roles which I have thoroughly enjoyed. B...
2013
Subnetting Made Easy - Index
Below is a list of all the posts in the “Subnetting Made Easy” series: Subnetting Made Easy, Part 1 Subnetting Made Easy, Part 2 Subnetting Made Easy...
Zone-Based Policy Firewall, Part 2
In my previous post I touched on the four parts (Zones & Zone Members, Class Maps, Policy Maps and Zone Pairs) which make up a ZFW configuration. In this...
Zone-Based Policy Firewall, Part 1
Cisco’s Zone-Based Policy Firewall (ZFW) can be quite confusing when you first start looking in to it, so over the next couple of blog posts I hope to provid...
Subnetting Made Easy, Part 3
Note: For the first post in this series, please see the Subnetting Made Easy, Part 1 post. Recently I received an e-mail from a reader who was having troubl...
Shape Average Vs Shape Peak - Part 3
In my previous post in this series I covered the difference between Shape Average, Shape Peak and Shape with no Excess. Now that that’s out of the way, let’s...
EIGRP No Auto Summary Command, Part 2
A few years ago I wrote a blog post about EIGRP and the “auto-summary” command called EIGRP No Auto Summary Command, Part 1. In that post I provided a brief ...
MTU Vs MSS - Part Two
A little while back I posted an entry called MTU Vs MSS - Part One. At the time the plan was to follow it up with Part Two a short time later, however, here ...
Understanding MQC Series
Series Index I am in the process of writing a series of blog posts which will cover: Modular QoS CLI (MQC) Weighted Fair Queue (WFQ) Class-Based Wei...
Understanding MQC, Part 3: Output Analysis
In my previous post I implemented a basic QoS configuration. In this post I will demonstrate how the “bandwidth” and “priority” commands treat their respecti...
Understanding MQC, Part 2: Basic Configuration
In my previous post I mentioned the six steps which are required in order to implement a QoS solution. In this post I’ll use those steps to create an example...
Understanding MQC, Part 1: The Basics
Over the course of my next few blog posts I will be covering Modular QoS CLI (MQC), Weighted Fair Queue (WFQ), Class-Based Weighed Fair Queuing (CBWFQ) and L...
New Website Launch - Ultimate Cisco Lab
In the Connecting Your PC to Your Virtual GNS3 Routers post I provided basic instructions explaining how you can connect your PC to your GNS3 topology, allow...
Shape Average Vs Shape Peak - Part 2
Note: If you haven’t read Shape Average Vs Shape Peak - Part 1 already, I suggest you read it first and then return to this entry. Three Types of Shaping T...
Shape Average Vs Shape Peak - Part 1
When I first started looking in to the differences between Shape Average and Shape Peak, I soon found myself getting lost in all of the acronyms - Tc, Bc, Be...
StackExchange - Network Engineering
Just a quick post in case you haven’t seen it already - we’re trying to get a “Network Engineering” site going over at StackExchange. If you’re interested, p...
2012
Virtual Equipment + Physical Equipment = Big Lab
I have posted a few entries covering GNS3 and how you can use it to help you with your studies. And, in the Connecting Your PC to Your Virtual GNS3 Routers I...
New PC - Nexus 1000V here I come!
As per my previous post, I have been in the market for a new PC for a little while now and have finally made a purchase. The specs can be found below. CP...
Download & Install Nexus 1000v For Free!
Cisco has recently announced that the Nexus 1000v can be downloaded and installed free of charge. This is great news for those of us who use VMware products,...
Saving GNS3 Topologies
A lot of people (myself included) have had trouble saving their GNS3 topologies properly. You think you’ve done it properly, only to find the next time you o...
MTU Vs MSS - Part One
Have you ever seen the below configuration and wondered what these commands do? And why the MSS value always seems to be 40 bytes lower than the MTU? interf...
GNS3 IOS Memory Errors - Solution
In a previous post I talked about GNS3 memory errors that produced the below log messages when certain IOS images were used and NATing was enabled: R1(confi...
2011
About Me
Original (November 2011): 2015 Update: See this page to find out what I’ve been up to over the years since this entry was originally posted. I have receive...
Fast GNS3 Router Bootup
As all Cisco IOS users/Cisco engineers will have seen when booting up a switch or a router, the device will decompress the image file which is represented by...
Emulating a Multi Layer Switch in GNS3
As most of you know, you can get switch-like capabilities in GNS3 by inserting a NM-16ESW in to a compatible router. This is necessary because at present, dy...
GNS3 Duplex Mismatch Messages
When Cisco devices are connected to one another and CDP is enabled (which it is by default), if one port is configured as full duplex but the other is config...
GNS3 IOS Memory Errors
Update: Please see this page for a fix to this issue. The other day I decided to upgrade my GNS3 IOS to c3725-adventerprisek9-mz.124-15.T14.bin. All seemed ...
Connecting Your PC to Your Virtual GNS3 Routers
Update: Please also see my Virtual Equipment + Physical Equipment = Big Lab post for more information. As you already know, GNS3 allows you to create virtua...
URL Redirects using NAT
In my previous post, Router URL Filtering using NBAR, I explained how it was possible to block users from accessing websites simply by using NBAR, a class-ma...
Subnetting Made Easy - Formula
I covered subnetting in my earlier posts, Subnetting Made Easy, Part 1 and Subnetting Made Easy, Part 2. In the latter mentioned post, I explained how you c...
Router URL Filtering using NBAR
There are many ways you can block users from accessing websites they shouldn’t be, such as firewalls, proxy servers, DNS servers, etc. However, if you have a...
Subnetting Made Easy, Part 2
In my previous post, Subnetting Made Easy, Part 1, I demonstrated the way I use to find the Network Address, First Usable Address, Last Usable Address and Br...
Subnetting Made Easy, Part 1
There are a wide range of techniques people use to work out their network, host and broadcast addresses. I prefer to take the binary approach as I find it th...
Single Public IP NATing to Multiple Hosts
In my previous blog entry, Multiple Public IP NATing to Multiple Hosts, I described how you can use “one to one” NATing to allocate one public IP address per...
Multiple Public IP NATing to Multiple Hosts
I have seen quite a lot of ask the question, “how do I NAT multiple public IPs to multiple inside hosts?”. I think what confuses most people is when they are...
EIGRP Network Command Tips
I discussed the EIGRP “network” command in the EIGEP Network Command – The Easy Way Out post, as well as the EIGRP Route Advertising post, and I’m about to d...
EIGRP Network Command - The Easy Way Out
In my EIGRP Route Advertising post I said “in order for two routers to exchange EIGRP routes, they must both be part of the same subnet and have a network co...
The “do” Command
Don’t you just hate it when your in the middle of implementing a new configuration but then decide you’d like to issue a “show” or “ping” command so you drop...
Dangers of the EIGRP “Neighbor” Command
I have touched on EIGRP a few times before and here we are again. In my EIGRP Route Advertising post I explained how EIGRP neighbor relationships can be cre...
2010
EIGRP No Auto Summary Command, Part 1
In my previous post about EIGRP Route Advertisements I touched on the “no auto-summary” command, but did not delve in to the details of what this command act...
EIGRP Route Advertising
In the forums that I frequently visit I always see people asking how EIGRP route advertising works. The users are not sure how to correctly use the “network”...
Get Involved - Forums
Whether you are are a seasoned Cisco professional or just starting out, one of the best sources of information you will find (apart from this blog :P) are in...
CBAC in Action, Part 2
In my previous CBAC post I covered how to deny all external traffic unless it is in response to a request someone on the LAN has made, e.g If you send a ping...
CBAC in Action, Part 1
In a previous post I talked about CBAC and a few of the ways in which it, in conjunction with NBAR can be used to secure your network. Today I will create a ...
CBAC Firewall
In my previous post I mentioned the Cisco IOS firewall feature known as CBAC (Context-Based Access Control). Today I will describe it in more detail and expl...
NBAR and its Many Uses
NBAR, also known as Network Based Application Recognition is an invaluable tool that many people do not know exists or simply just don’t use it enough. As t...
GNS3 + Real Cisco Gear
For those of you who have never heard of GNS3 before, you are in for a treat! What it does is allow you to run multiple routers on your computer in a virtua...
Welcome!
Hello and welcome to my blog. I know what you are thinking, “not another Cisco Blog!”, but this one will be different, I promise :) The point of this blog ...