I debated whether to write an article like this. It seems to be the “in vogue” thing to do if you’re a blog author but I wasn’t inclined to do it until I started looking at the data (I heart data). When I started looking at the data, I saw not only number of visitors and so on to the blog, but a breakdown of browser versions and operating systems (thank you Google Analytics for the rich reports). As is often the case, your data set can tell you more than you initially bargained on. Read More >>
I was preparing a presentation the other day about the high level differences between IOS, IOS-XE and NX-OS and one of the things I included in the presentation was the various platform and branch identifiers that’s used in each OS. It’s just a bit of trivia that I thought would be interesting and might come in handy one day. I’m posting the information I collected below so everyone can reference it.
It seems appropriate to write a FFF post about Virtual Extensible LAN (VXLAN) now since VXLAN is the new hotness in the data center these days. With VMware’s NSX using VLXAN (among other overlays) as a core part of its overall solution and the recent announcement of Cisco’s Application Centric Infrastructure (ACI) and the accompanying Nexus 9000 switch, both of which leverage VXLAN for delivering a network fabric, it seems inevitable that network engineers will have to use and understand VXLAN in the not too distant future.
As usual, this post is not meant to be an introduction to the technology; I assume you have at least a passing familiarity with VXLAN. Instead, I will jump right into 5 operational/technical/functional aspects of the protocol.
I was prompted to write this when I observed someone the other day who was sitting in the same training as me taking notes in a self-addressed email. No offense to people who do this, but W. T. F. How are you going to keep track of that email among the dozens/hundreds you receive every single day?
I take a lot of notes for research, certification study, and training. I use MediaWiki for almost all of these notes. Here’s why. Read More >>
Following on from my previous “triple-F” article (Five Functional Facts about FabricPath), I thought I would apply the same concept to the topic of Overlay Transport Virtualization (OTV). This post will not describe much of the foundational concepts of OTV, but will dive right into how it actually functions in practice. A reasonable introduction to OTV can be found in my series on Data Center Interconnects.
So without any more preamble, here are five functional facts about OTV.
Normally I talk about overlays in the context of data center/SDN/cloud but today I’m going out into left field and am going to talk about voice! :-)
I freely admit that I’m a noob when it comes to Cisco voice so I’m not sure if the behavior I’m about to describe is obvious or not. It wasn’t obvious to me and I only figured it out after running into the issue for real and troubleshooting it to resolution.
The issue stems from my misunderstanding about how dual-line ephone-dns function when used in an overlay. Read More >>
This post is about finding and fixing a memory leak I discovered in the SNMP daemon, snmpd(8), in OpenBSD. This sort of analysis is foreign territory for me; I’m not a software hacker by day. However, using instructions written by Otto Moerbeek as my Rosetta stone and Google to fill in the blanks when it came to usage of the GNU debugger, gdb(1), I was able to find and fix the memory leak.
I’m documenting the steps I used for my future self and for others.
Let’s step back for a minute. So far in this series of blog posts on DCI, I’ve been focusing on extending the Layer 2 domain between data centers with the goal of supporting hot migrations — ie, moving a virtual machine between sites while it’s online and servicing users.
As a follow-on to my previous article on onePK – Cisco onePK: Now I Get It – I recorded a screencast in which I talk about what a onePK-enabled network is capable of. I also demonstrate two applications which make use of onePK to gather telemetry from the network and also program the network.
MTU Checker – Verifies that when the MTU of an interface is changed on the CLI, that the adjoining interface MTU matches
Routing For Dollars – Programs the forwarding table of the routers in the network based on the cost – in terms of dollars – of the various links in the network
Please leave a comment below with any questions or feedback.
I had an opportunity recently to sit in a Cisco onePK lab and it opened my eyes to exactly what Cisco is doing with onePK, why it’s going to be so important as Software Defined Networking (SDN) continues to gain traction, and why onePK is different than what anyone else is doing in the industry.
onePK is a key element within Cisco’s announced Open Network Environment SDN strategy. onePK is an easy-to-use toolkit for development, automation, rapid service creation and more. It enables you to access the valuable data inside your network via easy-to-use APIs.
Since having my own eyes opened, I’ve been pondering how to explain my new found understanding in a way that others will grasp. In particular to business decision makers (BDMs) and technical decision makers (TDMs). I’m really, really, struggling to come up with a good analogy for BDMs. I’m still working on that one. Surprisingly, I’m also struggling to come up with a sound analogy that will work with the majority of TDMs that I know. Maybe I shouldn’t be so surprised at that since all the TDMs I deal with are on the infrastructure side of things (networks, storage, compute, platform) and really don’t deal with software. There’s a gap there that I somehow need to bridge. I’m still pondering how to successfully do that.
However, there is a slice of the TDM population that I believe I can reach right now. These folks, like myself, have software and network experience. Maybe through open source projects, previous careers, or just mucking about with LAMP stacks in their own lab/home network, they understand programming semantics, APIs, and extending the functionality of third-party software.
I’m going to use a popular open source software package to draw some parallels with what Cisco onePK will soon allow organizations to do to their networks. Read More >>
Joel Knight is a Systems Engineer with Cisco Systems and is responsible for working with enterprise customers to help them understand Cisco products and solutions through technical briefings, architecture and design sessions, and competitive analysis.