packetmischief.ca

Wow the title of this post is a mouthful.

Similar to my previous post on the Nexus 2000 (Nexus 2000 Model Number Cheat Sheet), this post will explain what the letters and numbers mean in the Nexus 7000 IO module part numbers. This will allow you to quickly identify the characteristics of the card just by looking at the part number which in turn should help you out as you’re building BOMs and picking the right card for the job.

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This is the third article in my series on Data Center Interconnection (DCI). In the first (Why is there a “Wrong Way” to Interconnect Data Centers?) I wrote about the risks associated with DCI when the method chosen is to stretch Layer 2 domains between the data centers.

In the second article (DCI: Why is Stretched Layer 2 Needed?) I wrote about why the need exists for stretching Layer 2 domains between sites and also touched on why it’s such a common element in many DCI strategies.

In this article, I’m going to put all that soft stuff aside and get down into some technical methods for achieving a shared Layer 2 domain (ie, same IP subnet in both sites) while managing risk and putting a design in place that is resilient to Layer 2 failures. Namely, I’m going to talk about a protocol called Overlay Transport Virtualization (OTV).
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In the previous article in this DCI series (Why is there a “Wrong Way” to Interconnect Datacenters?) I explained the business case for having multiple data centers and then closed by warning that extending Layer 2 domains was a path to disaster and undermined the resiliency of having two data centers.

Why then is stretching Layer 2 a) needed and b) a go-to maneuver for DCI.

Let’s look at it from two points of view: technology and business.

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There’s certainly a lot of focus on data center interconnection (DCI) right now. And understandably so since there are many trends in the industry that are making IT organizations look at data center redundancy. Among these trends are:

1. The business is saying to IT that they require their IT services to be available at all times. In effect the business is saying that they want to be shielded from technology issues, maintenance windows, and unplanned downtime because the IT services they consume (not all of them mind you, but certainly some of them) are so critical to running the business that they cannot be without them (or, they cannot be without them for whatever period of time it would take IT to recover the service).
2. The technical ability to move workloads between sites thanks to the near ubiquity of features like vMotion and Live Migration. The ability to pick up an application and swing it over to another location makes item #1 above far less daunting to IT shops and lowers the barrier to adoption.

In this post I’m going to talk about how IT can address item #1 above – the business need – in a manner that does not introduce hidden risk into the environment. This is a common conversation that a lot of IT organizations are having right now but unfortunately the easiest and most obvious outcome from those conversations is not always the one with the least risk.

In the second post of this DCI mini series, I’ll talk more about item #2 since that’s the one that drives a lot of the technical requirements that have to be met when delivering the overall solution to address #1. Read More >>

As I wrote about before (Creating a CCNA Voice Lab) I’ve been studying for another Cisco certification. As I was studying for the exam, I started thinking about the tools I was using to prepare. It wasn’t that long ago that my tools were limited to pen and paper (does that make me sound old?? Uhhg). Now, I have a tablet, smart phone, and of course the venerable “cloud” for storing PDFs, notes, etc.

Anyway, I thought it would be neat to document the tools I’m using today. It’ll be interesting to read this in a couple of years to see how things have changed again and maybe it’ll give a fellow cert-chaser some ideas for today. Read More >>

I’ve been working on something that at this point in my career I never thought I’d be doing: another Cisco Certified Network Associate (CCNA) certification. The CCNA Voice, to be exact. Now that I’m in a job role where I’m expected to be somewhat of a jack-of-all-trades, I can no longer avoid learning voice :-) For a long time I’ve focused on just the underlying network bits and left the voice “stuff” to others. Since I now need to talk intelligently about Cisco voice solutions, products, and architectures, I decided to go through the CCNA Voice curriculum as a way to establish some foundational knowledge.

This post is about the tools and methods I used to build a small lab to support my studies. Read More >>

There’s a new Nexus in the family, the Nexus 6000. Here are the highlights.

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I’m not sure why I’ve taken such an interest in mDNS, service discovery, and the Bonjour protocol, but I have. It probably has something to do with my not being able to use AirPlay at home for such a long time because, like any true network geek, I put my wireless devices on a separate VLAN from my home media devices. I mean, duh. So now I keep an eye out for different methods of enabling mDNS in the network in anticipation of my own experience in my home network becoming one of my customer’s experience in their enterprise network. Read More >>

I installed OmniOS on my home filer over the Christmas break. Jumping from a Solaris Nevada build to OmniOS meant figuring out what software packages are available in the OmniOS repositories, what third-party repos are available and what software I would have to compile by hand. Given that this machine is only acting as a filer and isn’t running any other services to speak of, the list of software to get up and running is small; however a critical component is apcupsd which talks to the Uninterruptible Power Supply (UPS) and cleanly powers down the filer if the power goes out for an extended time.

The hangup for me is that my UPS connects to the filer via USB, not a serial connection. It took me some hours to figure out how to get apcupsd installed with USB support. Here’s how. Read More >>

Ahh the Christmas break. The perfect time for good food, enjoying the company of family and friends and of course…. IT projects at home! My project last year was to immerse myself in the source code for OpenBSD’s snmp daemon so that I could integrate my patch-set for Net-SNMP directly into the native OpenBSD daemon. That was time well spent as I was able to integrate my code in the following weeks. This year I have maintenance to do in the home lab. It looks like 2013 is going to be a busy year as far as getting my hands on new stuff so I want the lab ready to rock.

First project: upgrade my VMware ESXi server from 4.1 to 5.1. Read More >>