Packets DownRange
If you’ve ever dug into the interface stats on a router or switch and seen a growing count of FCS errors or RX errors, you’re likely wondering: what do these mean—and should I be worried? The short answer: yes, you should investigate. These errors can indicate deeper issues in your network that may be causing … Read more
When BGP (Border Gateway Protocol) misbehaves, the ripple effect can be massive—routes disappear, prefixes flap, and connectivity grinds to a halt. Whether you’re managing a large enterprise edge or an ISP core, knowing how to quickly diagnose BGP issues on Cisco routers is critical. Here’s a hands-on guide to the most useful Cisco IOS BGP … Read more
MikroTik Torch is one of the most powerful and versatile tools included in MikroTik’s RouterOS for real-time traffic analysis. Whether you’re troubleshooting network issues, monitoring bandwidth usage, or identifying unusual traffic, Torch can help you gain deep insights into your network’s behavior. In this guide, we’ll explore how to use MikroTik Torch effectively. What Is … Read more
Here are some steps to solve a customer’s home router slowness issue. I have found over the years 90+% of customer issues can be traced to the router at their home or location. 1. Diagnose the Problem Start by asking the customer for more details. Many times what is the problem is not really what … Read more
Over the years I have been able to narrow the most common reasons a service provider goes down or has an outage. This is, by no means, an extensive list. Let’s jump in. Layer1 outages Physical layer outages are the easiest and where you should always start. If you have had any kind of formal … Read more
Recently I ran into an issue where a librenms install was taking up a crazy amount of disk space. This was tracked down to the syslog.ibd file . Even thought I had set my options to be less than 10 days per this link https://docs.librenms.org/Support/Cleanup-options/ I still was having a huge file. Here is what … Read more
Recently, there was a thread on the NANOG list asking what were somne favorite network troubleshooting tools. I have taken many of these tools and created the following list. http://ping.pe/Simple pingport and dig commands https://mtr.sh/BGP Looking glass https://perfops.net/mtr-from-worldTraceroute from various hosts on the net http://www.traceroute6.net/IPV6 tools (ping,traceroute,etc) https://dnsviz.net/Carious DNS tools http://irrexplorer.nlnog.net/Routing Registry object explorer https://mxtoolbox.com/DNS … Read more
https://www.thefoa.org/tech/ref/testing/OTDR/OTDR-FAQS.html?fbclid=IwAR1wWEr5qG0h4r2vBsnEEmCWrT20VYIWGCnseOD2_MChJiaL6PX9RaCm1ow Frequently Asked Questions On OTDRS And Hints On Their Use OTDRs, also known by their technical name optical time domain reflectometers, are valuable fiber optic testers when used properly, but improper use can be misleading and, in our experience, lead to expensive mistakes for the contractor. We have been personally involved in several instances … Read more
Just a reminder that rebooting does help. My home network was experiencing slowness and lag
MTR is a visual application that combines the functionality of the traceroute and ping in a single network diagnostic tool.
This content is for Patreon subscribers of the j2 blog. Please consider becoming a Patreon subscriber for as little as $1 a month. This helps to provide higher quality content, more podcasts, and other goodies on this blog.To view this content, you must be a member of Justin’s Patreon Unlock with PatreonAlready a qualifying Patreon … Read more
Podcast: Play in new window | Download (Duration: 7:22 — 10.3MB)
Troubleshooting for ISP networks. Quick podcast on using layers 1-3 for making your admin life easier.