L2 Basics: Configuring an EtherChannel

Today we’re going to take a look at how to configure an etherchannel between two Cisco Switches. What is an etherchannel? It’s a way of taking multiple independent links and bundling them together, so that they appear as one logical connection between two devices. Etherchannels are…

What's wrong with VLAN 1?

Earlier this year I was involved in a string of interviews for an open network engineer position. The questions and scenarios provided during the interviews were aimed for someone mid-level. One of the more basic-ish scenario questions I like to ask is the following: Given a brand new switch, can…

L2 Basics: Spanning-Tree Protocol

Spanning-tree protocol (STP) is one of those network technologies that is easy to forget about. It exists in the background of almost every network, and for the most part it does it’s job without any issues. However, there is still a huge benefit to understanding what STP does…

Quick Tips for Better BGP

A while back I wrote some basic information on how to get started implementing¬†multi-homed internet using BGP. The details and configurations listed in that post are enough to get the connection up and running – but not quite in an ideal state. So today I want to share some…

BGP: Getting Started with Multi-homed Internet

A few years back I worked for an organization that had a single 100Mb Internet connection. Not bad for just typical corporate traffic, but we also hosted our production web site out of that location as well. An incident occurred where our website was down due to Internet issues during…

IP Address Design (Part 2)

Last week in IP Address Design (Part 1)¬†we discussed an example of a bad design for IP allocations and the problems that it caused. This week we will continue by discussing the proposed solution and how it resolved those issues. The problems with our IP Addressing scheme bothered me…

IP Address Design (Part 1)

It’s funny when you think about basic networking concepts and wonder if they will ever actually prove to be useful. Kind of like that “Do I really need to learn complex geometry? When am I ever going to use this?”. What I’m here to…