443 posts categorized "Test & Measurement" Feed

Why Bother with Ethernet Cabling. (by Tony Fortunato)

I think there is a balance between doing it yourself and calling the professionals. If it’s a straight forward manageable task and you have the correct tools and knowledge, why not.

For example, I wouldn’t climb an 80 foot tower, pull and terminate 120 pairs of Ethernet cabling or try to terminate fibre connectors.

While working onsite I was asked “Why bother?“ or “We’ll get someone else to do that”. Some people feel that some network tasks are too menial or beneath them. I’ve had some network technicians ask why I would bother doing ‘that kind of work’ when you have had various certifications.

There are many answers; I like the variety, I enjoy keeping my skills sharp, and the job gets done quicker. I find I can add more value to a design or install since I have physically done the work as opposed to just reading the materials. The bonus is that when I watch people do incorrect installations, I have more things to look for when troubleshooting problems.

Here’s a simple example: we had to pull and terminate 3 Ethernet cables as part of an install. The technician said “let’s just call the cabling company to do it”. I asked how long that would take and he responded 2 to 3 days. I reminded him that I was only there for the day and added that it would not take us long to pull three cables 20 feet and terminate them ourselves. The cables were a straight run in the cabling trays above our heads.

Just a quick disclaimer; if you have no experience terminating cables, do not practice or learn on your production environment. Fortunately I have been terminating Ethernet cables for over 20 years, so this is a fairly simple process. I went to my vehicle and got a spool of cable, some RJ 45 connectors as well as my crimper. Fortunately, I had assumed that I might need to do this type of work and had prepared myself with the proper supplies and my vehicle.

Flashback; I will never forget working with network consultants at a new build and I was the only one with tools, a hard hat and my government safety certificates, even though everyone was told this is a construction area. The other consultants  were limited when, and where they could work where I had the run of the place.

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Microsoft getmac and MAC Address (by Tony Fortunato)

When troubleshooting it is quite common to get the mac address of the host, server or network equipment for a variety of reasons.

For example, many syslog messages or logs may refer to mac addresses depending on what the error is. If you are working from the switch, you more than likely need to know the mac address if you need to figure out which port the target is for your monitor or span command. And of course if you are using a protocol analyzer, you should always capture with a mac address, when possible.

In this video I review how most people figure out their mac address and how to determine the mac address of another device on the same vlan as you. The issue with this methodology is that in some scenarios you may want to figure out the mac address of a Microsoft device that is on another VLAN.

Using Microsoft’s getmac command allows you to get your mac address as well as a remote system’s mac address. As I mention in the video, this command seems to be using the DCE/RPC protocol, so if you block this protocol on your host, servers, or network you might have an issue with command.

Lastly, you need to know the user name/password on the remote system for this to work remotely.

Hope this helps you with your troubleshooting.

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Four best practices that can ensure application health in an Hybrid IT environment! (by Will Moonen)

In a digitally transformative world where the end-user experience (EuE) is a #1 business priority, understanding how applications perform, especially in hybrid IT environments with multiple security layers, is critical.

Here are four best practices that can ensure application health in these environments.

Graphic 1Best Practice #1: Having the right level of plumbing

Start by knowing if you have the right level of plumbing; that is, ensuring that all relevant packets are captured as they travel across the infrastructure.

Since security policies often take precedence when it comes to managing the entire IT infrastructure, when we look at deployment strategies specific to security appliances, we find that most strategies align these appliances with the application streams. Depending upon the company size and other factors, there may be multiple security appliances, which creates additional security zones (or segments).

This calls for the development of a schematic, conceptual overview addressing all branches/remote offices, datacenter(s), and cloud services, including the application flows.

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Troubleshooting a Spotty/Bad Internet Connection (by Chris Greer)

Recently, I changed my internet service to a new provider. These guys promised some decent bandwidth at a good price.

After getting it installed, nerd-proofed, and monitored, all looked good.

That is until I had a remote training class to teach over WebEx – then the audio issues began. (Of course! Why do these issues always KNOW?!?! Right when you need the connection the most – boom!)

Every 10-15 minutes or so the audio would drop for about 5 seconds. The students could still see my screen, but the audio was clearly having issues. Fortunately, I could call in using my cell and finish up the class with no further problems.

As much as I wanted to blame WebEx, I knew that it was no small coincidence that I had just changed my internet service. Alas, this time it looked like it really was the network! Time to crack out the tools and troubleshoot.

Packet Capture - Wireshark

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Layer 1 Troubleshooting Scenario (by Tony Fortunato)

In this article I wanted to review a current troubleshooting scenario that I thought you would benefit from.  The point of the article is that you should never overlook the basics.

While working onsite, I overheard a group of technicians discussing a current issue with a WiFi radio on a tower. Their management system reported that the radio was down and probably had to be replaced. One of the issues is that they have to get a hold of someone to climb the tower which means that the outage only gets longer. After they located someone I asked what was going on.

The senior analyst explained that his happens every so often and the radio just needs to be replaced with a new one.  I then asked if they would mind showing me around since we were just waiting for the contractor and they said no problem.

We walked over to the bottom of the tower, opened the enclosure and noticed that smell of burnt popcorn. There obviously wasn’t any popcorn there, that’s just my way of describing the smell of burnt cable or electronics. After some poking around, I determined that they needed to replace a lot more than just the radio.  In the video, I explain what I looked for, what I found and what I suggested. 

While waiting for the contractor, i also suggested that we review their grounding.

 

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