Linux Network Interface Configuration With udev

I've recently been running down (or is it through) the Linux, systemd, networkd, udevd rabbit hole at full pelt and thought … [Read more...]

OpenStack Neutron – The Dirty Network Detail

OpenStack Neutron Networking

Update: I'm slowly getting there, third and more accurate diagram attached below which now includes where security policies, … [Read more...]

Network Design Concepts Part-3

In the first article of the series, reliability and resiliency are covered. We should know that whatever device, link type or … [Read more...]

Network Design Concepts Part-2

In the first article of this series, reliability and resiliency has been explained. Every component and every device can and … [Read more...]

Why logging is so important? VSS example.

Example: Why switch in VSS mode crashed? Few weeks ago there was a great podcast about logging (show 192). Recently I came … [Read more...]

More DHCP Snooping

Screen Shot 2014-08-07 at 12.47.37

This post is a follow up to Ethan's post and Edward's post. Both were very useful to me as I began to plan rolling out this … [Read more...]

Anycast HSRP and Design Considerations


HSRP is the first hop redundancy Cisco property protocol which allows a transparent failover of the first-hop gateway. Many … [Read more...]

When Good NICs Do Bad Things: A Blast of IPv6 Multicast Listener Discovery Queries

This is the write-up of a recent event we experienced on our network.  This will be combination of a  journal of symptoms, … [Read more...]

Cisco Internal VLAN Usage


About a month ago I worked on an old CatOS switch. Working on this switch reminded me about some of the differences between … [Read more...]

Out with the old, in with the new


A few weeks ago I was asked to help a client turn up and move everything over to a new network. I have done this many times … [Read more...]

Kicking tires on Cumulus Linux


So, I ended my last blog post with a wish - "hopefully someday I can get a real switch running Cumulus to play with ;-)" … [Read more...]

Fast Reroute Mechanisms


Network reliability is an important measure for deployability of sensitive applications. When a link, node or SRLG failure … [Read more...]

Switching to Linux for… Switches?

Lab whiteboard drawing

Like many folks out there, I'm following the rise of "whitebox switching", and am interested to see if (and where) it takes … [Read more...]

Don’t Need No Stinking Underlays

Why's everyone complaining about overlays; it's the underlays that are the problem. I've been in this awful game for … [Read more...]

Speaker for the Dead – Spanning Tree Protocol


A friend of mine* text me early last week asking if I wanted to go to the cinema and watch the film After Earth. I … [Read more...]