John Harrington
Author Archives: John Harrington
- Home → Author's archive:
John Harrington
Solarwinds Geek Speak
I wrote a few articles for the Solarwinds Geek Speak blog that I’d like to share. They are short articles, but I think you’ll find some value in each. Start with the 80/20 rule below post below and read the rest if … Continue reading
The post Solarwinds Geek Speak appeared first on The Network Sherpa.
The Feynman Principle
Interviews often start with softball questions like… So why are you interesting in working for our company? This question gives the candidate an easy way to warm-up and could give the interviewer some insights into the candidate. I’ve asked this question … Continue reading
The post The Feynman Principle appeared first on The Network Sherpa.
Reserved Internal Address Ranges
I’ve added a new question to my own network integration checklist, specifically when integrating chassis-based or integrated solutions: Does the system use any reserved internal address ranges? Some chassis-based systems reserve private IP address ranges for inter-card communication. This is a … Continue reading
The post Reserved Internal Address Ranges appeared first on The Network Sherpa.
Strain relief
I’ve got a problem with sagging cables, and I’ve got a simple solution. Examine the side-by-side images below which show the same fiber connection between a switch and a firewall. The image on the left shows a sagging cable which crosses in front of … Continue reading
The post Strain relief appeared first on The Network Sherpa.
Effectiveness – Network Truths, Principles and Fallacies
I gave a 13-minute talk to the Irish Network Operators Group (INOG) recently. In this 13-minute video I argue that you can become more effective, and happier, by standing back and reflecting on how you work, leveraging existing truths, fallacies and principles. I introduce The twelve … Continue reading
The post Effectiveness – Network Truths, Principles and Fallacies appeared first on The Network Sherpa.
Clear Pricing for Network Services
I had to buy some switches recently and needed to gather a second quote from another vendor. I went to the Dell website and was pleasantly surprised to quickly find a clear price and a buy-now button for each device on their website. Normally … Continue reading
The post Clear Pricing for Network Services appeared first on The Network Sherpa.
Writing elsewhere on the net
Hi Folks, I write for a few other publications, so I’ve made this handy page to link to external articles. I’ll update this page as new articles are released. Human Infrastructure Magazine Issue 23 – How To Unblock Your Project Issue … Continue reading
The post Writing elsewhere on the net appeared first on The Network Sherpa.
Include the why
I recently stumbled upon an interesting commencement speech by Charlie Munger of Bershire Hathaway fame. Charlie is Warren Buffet’s right-hand-man, and a straight talking genius in his own right. It’s a fairly long speech and Charlie has a few very … Continue reading
The post Include the why appeared first on The Network Sherpa.
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 … Continue reading
The post Getting started with Network Packet Generators appeared first on The Network Sherpa.
5 ways to fail – WAN link acceptance
I’ve had an interesting few months doing WAN circuit turn-ups for a new Data Centre. I dealt with three major carriers, and each experience was worse than the next. I’m not sure why I held such high expectations but I was … Continue reading
The post 5 ways to fail – WAN link acceptance appeared first on The Network Sherpa.
Does your Wave2 AP need NBase-T?
Cisco recently launched the 2800 and 3800 series 802.11ac wave-2 access points. The 3800 Datasheet quotes a theoretical maximum throughput of 5.2Gbps when operating in Dual 5GHz radio mode (2 x 2.6Gbps). If you ran two cables to your AP you could … Continue reading
The post Does your Wave2 AP need NBase-T? appeared first on The Network Sherpa.
Programmable ASICs
I love learning about network hardware, but I’ve always found it difficult to get detailed information on ASICS. We had a great presentation from Dave Zacks on the Cisco 3850 programmable ASIC at the Cisco Live Europe Tech Field Day … Continue reading
The post Programmable ASICs appeared first on The Network Sherpa.
East West Segmentation With ACI
East/west segmentation is required in the data center to protect backend networks from each other. Segmentation is often implemented using ACLs between VLANS on your core switch. The ACLS are maintained by network or security engineers but define the flows permitted … Continue reading
The post East West Segmentation With ACI appeared first on The Network Sherpa.
Thoughts on leaving Amazon
Hi All, I left Amazon in late 2015 to become an independent contractor. I took a contract working for a small managed service provider, which was closer to my home and offered a more family friendly schedule. It wasn’t an easy … Continue reading
The post Thoughts on leaving Amazon appeared first on The Network Sherpa.
Redistribution of named and tagged static routes
I always name my IOS static routes as a best practise. However I hit a syntax issue last week when I tried to combine the named static with a tag, then redistributing that tagged static route into OSPF. If you have … Continue reading
The post Redistribution of named and tagged static routes appeared first on The Network Sherpa.
Basic network change control process
Scenario: You are an engineer who runs a managed network on behalf of a customer. Your manager has asked you to create a change control process. Your customer and your manager will measure you only by the uptime or outages they experience, and … Continue reading
The post Basic network change control process appeared first on The Network Sherpa.
Network change – who is in control?
Network Change Nothing sparks engineering debate quite as much as ‘network change control’. It’s one of those topics we love to hate. We feel buried by useless bureaucracy. We ask, ‘Why can’t our managers just trust us, instead of weighing us … Continue reading
The post Network change – who is in control? appeared first on The Network Sherpa.
VTY ACL doesn’t block HTTP/S access
I was doing some testing on a 3750X and saw that the http and http servers were enabled. I knew you could apply an ACL to restrict HTTP access, but had assumed that the HTTP security was an optional extra on … Continue reading
The post VTY ACL doesn’t block HTTP/S access appeared first on The Network Sherpa.
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 … Continue reading
The post Link Utilisation Varies By Packet Size appeared first on The Network Sherpa.
SPAN Scaling Challenge
I’m facing a mini scaling challenge with Cisco SPAN (Switched Port ANalyzer) session and thought it would be good to share it with you fine folk. SPAN Challenge A 3750X switch is currently SPAN-ing a 10Gbps interface to a 1Gbps egress port. A … Continue reading
The post SPAN Scaling Challenge appeared first on The Network Sherpa.