LinkRunner AT 4000 versus Network Switch Cable Test (Carlo Zakarian)

 

I used to think the network switch was a master detective, capable of solving all my cable mysteries with a single, glowing link light, and remote management cable tests.  We’ve all seen these features on managed switches, select a port, perform a cable test, and watch for the results to be displayed as either pass, fail, split pair, and the length of the cable.

It wasn't until the feature-packed LinkRunner AT 4000 entered the scene that I realized the switch cable test was actually the network equivalent of a Magic 8-Ball, answering every complex problem with a confident “Yes, cable pass!” and not knowing why it passed.

Most technicians assume that if the switch reports “Cable Pass” the cable is having a great day. But if you want to know if that cable is suffering from a hidden split pair or just a minor existential crisis, you call in the Linkrunner AT 4000.

The LinkRunner AT 4000 is a handheld advanced network cable tester, it’s the stern, white-gloved proctor administering the final exam, it has a follow-up list of diagnostic questions, starting with “Did you remember to terminate correctly on both ends of the cable?”  The LRAT 4000 conveniently draws out the pin-to-pin wire mapping on the LCD screen, it can precisely measure cable fault via TDR, indicating cable problems such as split pairs, shorts, opens, mis-wired, and crossovers.  It also can test for port speeds, PoE, network and connectivity issues, and perform a full network map of your environment.  

Follow along with me and watch as I show you the difference between what a basic switch cable test reports versus a LinkRunner AT 4000 advanced precision cable tester.

Carlo Zakarian is a network engineer with over 15yrs experience in the networking implementation, design, and diagnostics field specializing in LAN, WAN, and Wireless.  Owner of NetFocus Technologies, an IT Managed consulting firm based in Chicago, specializes in setting up, configuring, diagnosing software, hardware, and network infrastructure.

 He can be reached via his website at https://www.NetFocusTech.com

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Using the LinkRunner AT 4000 for Surveillance Video Camera Installation

 I’m a big believer when it comes to hand held diagnostic tools, in that they should have several key features that can help you identify, validate, and report statistics to you.  Some common tools a network engineer has in their toolbox is a network cable tester, primarily used for testing network cable termination.  These tools are great when you’re trying to perform a quick check to see if a network cable is terminated properly.  And that right there is the issue-- it’s a quick check and not a complete comprehensive network cable test, validation, and reporting tool. 

 

Nowadays with so many devices running off of PoE, Integrated Layer-3 switch/firewall, multi-gig network interfaces, and not to mention a lack of an updated network diagram, it’s really hard to know how your installation and network devices will perform.

 

Enter NetAlly LinkRunner AT 4000 (LRAT-4000), a hand-held advanced network discovery and cable testing tool for multi-gigabit and fiber networks.  With a touch of a button, the LRAT-4000 will immediately and comprehensively perform a network discovery of all your devices, across multiple VLANS and subnets, with a path analysis.  It tests and verifies network cable and termination, coupled with advanced PoE testing up to 90W with TruePower loading, it displays device IP settings, DHCP, DNS with response time statistics, verifies link speed and duplex settings, performance testing with iPerf, packet capture at line-rate and so much more.

 

What I’m trying to tell you here is that the LRAT-4000 removes all of the guesswork of a basic cable tester/wire mapper and puts you in a position as a network admin to confidently know how your devices will perform without second guessing a single thing.

 

In this first video installment with the LRAT-4000, we perform a custom installation of a surveillance video camera system for a business site.  We begin with a network discovery of the site, followed by path analysis, test network cables, PoE load test, validate VLAN, IP, DNS, DHCP response times, performance test, packet capture, and reporting.  Follow along with me and watch how the LRAT-4000 makes this custom installation project a breeze.

Wireshark Packet Capture Limits on Linux Real-Time OS (Carlo Zakarian)

 There are a lot of dedicated hardware-based packet capture devices available that can capture at 1Gb and 10Gb line rate.  These hardware-based devices are designed with real-time Operating Systems, and specialized ASIC NICs with large buffer spaces to write to disk.  This method of acquiring packets guarantees that you will catch all of the bits going across the wire without dropping any of them. These are among the best to use when capturing on a very busy network, however, they come at a higher cost for a good reason.

When looking at the long list of options for capturing packets, most analysts prefer to use a laptop coupled with Wireshark.  The simple fact is that a laptop with Wireshark is convenient, it’s also very portable, cost-effective, and easy enough to use for an analyst.  The problem though is that most laptops and Operating Systems cannot capture at full line rate on a busy network.

However, what if there is a slightly better-performing Operating System out there?  RTOS or better known as Real-Time Operating System in Ubuntu kernel is perfect for those demanding low-latency requirements.  Ubuntu LTS with Real-Time capability can be a possible solution for low-latency captures.  Today, I will evaluate Wireshark on Ubuntu LTS with Real-Time enabled. 

Follow along with me as I use a Netscout Optiview XG traffic generator and blast unicast frames against our laptop with Ubuntu Linux RTOS.  We will test different frame sizes, utilization, data rates, and see how well it will perform under various conditions.  We will also examine at what data rates our Ubuntu Linux RTOS will begin dropping packets and compare those against our Ubuntu Linux running in normal run-time kernel. 

IoT WiFi goes offline at Night (Carlo Zakarian)

 It’s great when we come across IoT devices that can save us time and perform many automated tasks, like switching on our sprinkler lawn system, turn on lights as we walk into a room, make our morning coffee on a schedule, and set our AC/Heat thermostat temperatures.

Let’s face it, these devices work great most of the time, however nearly all lack wired connectivity which means most will work on WiFi only.  The problem with that is on occasion IoT WiFi devices can sometimes go on the fritz and not reconnect.  A simple reboot of your AP or device can usually fix it and other times a software update fixes it.  However, in some situations when you’ve tried just about everything else and it still doesn’t work, it may be time to a call in a qualified WiFi technician with some fancy commercial tools.

This brings us to the wonderful story of how I got called into a consulting gig to diagnose WiFi thermostats at a high-end gym.  The initial story was, thermostats are online during the day, but during the night some would turn off without a warning.  

As I quickly paced the hallways of my office, I thought to myself what could cause such an interesting problem - Is it a power issue?  Could it be WiFi interference? Is it a ghost, or some rodent having fun with wires at night?  So, I reached out for my duffle bag and placed in it my NetAlly AirMagnet WiFi Analyzer, NetScout Spectrum Analyzer, Fluke cable tester and headed out to the site.  
Let’s dig in and dissect this issue.   Follow along with me as I hunt down the culprit that is causing this issue and how I solved it.