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Category: Testing

Getting started with Network Packet Generators

Getting started with Network Packet Generators

A friend of mine has just ordered a shiny new packet generator for his network lab. I’ve spent some time working as a QA engineer in a network lab and wanted to share some advice. You can purchase stateful and stateless packet generators from major vendors like Spirent, IXIA or Agilent. If you just need to test throughput, latency or loss, a stateless packet generator will do the trick. The test hardware will use an ASIC to produce line-rate 10G traffic…

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Link Utilisation Varies By Packet Size

Link Utilisation Varies By Packet Size

I said to a colleague recently, “you can’t get 100% link utilisation on an Ethernet link”. When I tried to explain myself I wished I could link to a simple blog post with a nice graph. So here’s a quick blog post with a nice graph. I have talked a little about link speed in a previous post, but I wanted expand on this and add a quick graph to back up the argument.

Running vEOS in GNS3

Running vEOS in GNS3

A few weeks back I posted about my experience using VirtualBox to create running Arista vEOS instances. I loved how VirtualBox made is so easy to create VMs. However it seemed unwieldy and error prone to rely upon the VirtualBox console to attach each vEOS interface to a particular LAN segment. My last post explored using the CLI to create these mappings. I had planned to generate topologies using a script to create the appropriate vboxmanage commands at some later date….

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Create a VirtualBox Arista vEOS image from the command line

Create a VirtualBox Arista vEOS image from the command line

I’ve wanted to check out Arista EOS for a while, but didn’t have access to the hardware. I recently learned that Arista had made EOS available as a virtual machine. Arista call this vEOS. By installing the free VirtualBox hypervisor I could get vEOS running on my MacBook. It sounded a bit too easy, but to be fair the process is really well documented. Before I go further I should say that I obtained my copy of vEOS from my…

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Test – Throughput alchemy using a snake topology

Test – Throughput alchemy using a snake topology

Sometimes it’s best not to trust network vendor datasheets.  Nothing quite beats a controlled test of a network device in your lab with your config and your required features. But if you want to load test multiple ports on your 10G device-under-test (or DUT), then things can get very expensive, very fast.  In this post I’ll show a test topology that will help you turn 10Gbps of test traffic into 640Gbps or more.

OSPF – Setting MTU values for Cisco and Juniper

OSPF – Setting MTU values for Cisco and Juniper

MTU mismatches are the primary reason an OSPF adjacency becomes stuck in the EXSTART state.  After hellos are exchanged and the routers become neighbors, each OSPF speaker advertises the IP MTU of it’s local interface in a Data Base Description (DBD) LSA.  If there is a mismatch you’ll probably just adjust the configuration to be identical on both ends of the link and be done. However, when you try to peer two OSPF routers with different network operating systems, things…

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What is a physical layer switch?

What is a physical layer switch?

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.

Tester not included

Tester not included

A few years ago, I had the chance to attend an IXIA training course in our Dublin office. I had seen the time-suck of network test gear before.  So I said,  “I’m not spending a week trying to learn a test-set.  It’ll be cool, but what’s the point. I won’t get the time to apply those skills, then I’ll forget, and it will be a wasted week.”  I declined the training.

Get more juice from your network lab

Get more juice from your network lab

We have a network lab? Spirent presented their new lab-management software, called iTest Lab Optimizer, at network field day 4 recently.  Their product name isn’t catchy, but it is very descriptive and addresses a market need.  The simple fact is that most lab networks don’t get optimised to their full potential for some of the following reasons: Nobody knows what is in the lab (or that one exists) – Inventory Management The availability of the lab devices is unknown  – Availability and…

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