Posts in 2019
Inadvertent Transit
Thursday, April 25, 2019 in Networking
This blog post is about an actual real life, local network situation that happened several days ago. This is an excellent learning example about a perfect storm of small things causing a network outage. It is also an excellent learning example of how …
Fastnetmon on Ubuntu 18.04
Saturday, February 09, 2019 in Networking
I’ve spent some time trying to manually install Fastnetmon community edition on Ubuntu 18.04 Bionic Beaver. I was unsuccessful. However, I didn’t do an apt-cache search fastnetmon. There is a package in universe. Bionic Beaver also …
MRT Dumps with GoBGP
Wednesday, January 30, 2019 in Networking
I’ve been logging BGP route updates into MySQL for some time but this doesn’t scale well, and on my hobby VM system, requires that I dump the DB and start over once a day. One of the things I’ve wanted to do for a long time is to be …
Posts in 2017
fpinglog
Thursday, February 02, 2017 in Networking
I’ve often wished for a way of logging pings when troubleshooting connectivity problems. Today I revisited the problem using fping. fping and fping6 both have options to run a continuous ping (-l), and when combined with -D to insert the unix …
Posts in 2015
Working with ARINs Route Registry
Saturday, August 01, 2015 in Networking
This blog post provides a general overview of the Internet Routing Registry. If your network does not use IRR objects, you should have enough information to begin creating your own RPSL objects after after reading this post. What are Internet Route …
SSH Pubkeys with Cisco IOS 15
Sunday, May 31, 2015 in Networking
One of the new features of IOS 15 that I’m most excited about is the ability to use RSA public key authentication. This works on both switches and routers. Configuring public key authentication is pretty straight forward, in configuration mode …
Latency and Effects on TCP Performance
Thursday, April 30, 2015 in Networking
Have you ever used a download manager to download multiple threads, in order to max out or more fully utilize your connection? This is the effect of a small TCP receive window. How does latency factor into this? Bandwidth Delay Product Given the …
Posts in 2014
Well Executed Network Upgrades
Monday, July 28, 2014 in Networking
This past weekend a colleague and I executed a successful core network change, from stacked Cisco 3750G’s to Brocade ICX6610’s. We have been planning this upgrade for the past six months, and the extensive planning and testing before hand …
Brocade ICX Basics
Thursday, July 10, 2014 in Networking
I’ve been exposed to several different models of Brocade ICX switches lately, both the ICX6430 and the ICX6610. The ICX6430 is a low end gigabit-only, stackable layer2 access switch platform. While the ICX6610 is a feature rich …
ASCII Network Diagrams
Sunday, June 29, 2014 in Networking
I’ve often wondered if there is an easy way to generate ASCII network diagrams like those that appear in text RFC documents. This week I discovered ASCIIFlow. ASCIIFlow is really simple to use, and lets you draw boxes, lines, and arrows (for …