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Category: hardware

Video – Solving power connector confusion

Video – Solving power connector confusion

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Why talk about network power connectors? Here at Network Sherpa base camp, we’re all about removing confusion and saving time.   I’ve always had a bit of difficulty differentiating between the connector types,  PDU’s,  inlets outlets and country specific power cords. In this post I share my learnings. In the video below I focus on the commonly used low power IEC 320 series C13/14 connectors.  If you want further detail or more info about other connectors, then check out NetworkingNerds’s great…

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What is a physical layer switch?

What is a physical layer switch?

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I did a quick review of commercial lab management software recently when Spirent launched their Lab Optimizer software.  In the process I quickly glossed over physical layer (a.k.a. Layer-1) switches.  A physical layer switch is a powerful tool to have in a network lab or as a network tap, so let’s take a closer look at these devices.

Cut-through, corruption and CRC-stomping

Cut-through, corruption and CRC-stomping

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Corrupted frames are the devils spawn.  A few noisy links causing frame corruption can quickly degrade network performance, and troubleshooting them is getting harder.  These integrity errors generally occur when signal noise causes a binary ‘1’ to be mistaken for a binary ‘0’ or vice-versa.  This post takes a look at integrity errors and the impacts of corrupted frames in a cut-through switched network.  Throughout this post I’ll use the term ‘CRC errors’ term to refer to frame integrity errors which…

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Airflow is important – terminology is key

Airflow is important – terminology is key

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Data center cooling and large chassis As a network engineer you need to be aware of the data-center environment where your chosen device will be deployed.  A huge wedge of the cost of running a datacenter are spent trying to keep it cool.  So preserving hot-aisle and cold-aisle airflow containment is a big deal for your data-center manager.  But it’s pretty easy to order hardware that messes with the datacenter airflow.  You need to watch for context and read the…

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My 10G switch goes up to 11

My 10G switch goes up to 11

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Stealing bits Nailing down the true speed of a 10GbE link can be tricky. For a start you to define ‘speed’ and ‘capacity’. Ivan Pepelnjak offers a nice summary in this post. Then there are little surprises. A former colleague of mine Fred Westermark first introduced me to the Ethernet interframe gap. I had never heard of this before and felt a bit cheated to be honest.  Since when do ‘bits’ need a rest. Pfff.

Network design – scale without busting your budget

Network design – scale without busting your budget

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Rapid growth I read an article by Greg Ferro about twenty-percent-growth recently.  Greg makes the point that most network growth forecasts are grossly overoptimistic.   However, my experience in the service provider world is that ‘the business’ underestimates growth in most cases. Network engineers have a fiscal responsibility not to gold-plate their network designs; network gear is just too damn expensive.  But you can over-optimise for cost.  It is incredibly frustrating to overhaul and scale-up a network within a year of the initial…

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Using SNMP to switch APC power outlets

Using SNMP to switch APC power outlets

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Switchable PDUs In my day job I work as a network test engineer and support a remote lab.  We have  a few devices connected to network switchable PDUs that allow us to remotely reset the power outlet of test devices.  Test switches and routers get ‘borked’ pretty often so these switchable PDUs can come in really handy.

Video – 10G Fiber Transceivers – Network Sherpa

Video – 10G Fiber Transceivers – Network Sherpa

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I’ve just recorded a quick video about 10Gbps fiber transceivers, There’s a first for everything I guess.  It’s a cheat sheet which describes the different transceivers, where they’re commonly found and the connectors you use. I’d love to hear your take on the video.  Too long… too short, music too cheesy (yeah I know!), etc.   All constructive feedback is welcomed.

TCAM-based forwarding engines

TCAM-based forwarding engines

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Overview Ternary Content Addressable Memory, or TCAM,  is a critical component of a modern router. It is a powerful and fast hardware lookup engine for IP Prefixes.  It is also complex, expensive and power hungry.  Not surprisingly, there never seems to be never enough on whatever system you use. TCAM has historically been used to perform hardware-table lookups of Access-list, Netflow or QoS tables in routers and switches.   Most of these implementations from your favorite brand-name vendors use one…

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Are you paying too much for SFP+ transceivers?

Are you paying too much for SFP+ transceivers?

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The fiber transceiver industry When you buy transceivers for your switch, it is standard practice to order them from your network equipment manufacturer. However the switch vendor doesn’t actually manufacture these transceivers. There are a number of fiber interface transceiver manufacturers in the world, such as Finisar, Avago, JDSU, MRV, AOI, Delta and Wavesplitter. These vendors will supply a variant of their standard transceiver to the switch vendor for resale. The switch vendor will perform testing of that transceiver against…

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