The Network Stack

practical network tips/design/code

March 15, 2020 0 Comments

When working with AWS, there are plenty of features that make your life easier, but it's rare to find a feature that feels like magic...

Before we dive into the magic, what's the problem we're trying to solve? When working with servers anywhere, usually there needs to be some sort of remote access to SSH or RDP and install/troubleshoot things as needed. Worst case, your server has a public IP with port 22 (SSH) open to the world, which

November 30, 2018 0 Comments aws

At re:Invent 2018, AWS announced the Transit Gateway, finally giving us a native solution to provide scalable transit connectivity. After attending sessions and deploying Transit Gateway, I wanted to dive into the solution and see what is possible.

Tech Specs

In case you haven't read the official docs, the AWS Transit Gateway is a regional layer3 router connecting VPC, VPN, Direct Connect (soon) across multiple accounts, with support for multiple route tables (VRFs). The Transit Gateway (TGW) has much

November 12, 2018 0 Comments aws, ans

Can the AWS Certified Advanced Networking Specialty exam be legitemately passed with only a few weeks of studying? Yes.

Is there a secret shortcut? No.

Although there is no shortcut, I will discuss my previous experience, study materials, and general impressions of the exam. If you have already been working with AWS networking, and wondering what it takes to be certified, this post should give you a pretty good idea. Regarding my timeline, I passed the AWS Certified Solutions Architect

March 26, 2018 0 Comments ansible, cisco

Ansible 2.5 just came out, and with it comes new network modules (and the network_cli and netconf connectivity methods). The new modules allow us to manage certain IOS configurations without always depending on the "ios_config" module, while the network_cli connectivity method means we don't always need to configure a "provider" for every network playbook. These new modules and connectivity methods allow networking configuration management to look and feel similar to our server

February 19, 2018 0 Comments ruckus

A couple years ago I posted how to Optimize Ruckus Configuration, and since then I've been continually tweaking so that my dense, multi-story WiFi environment performs well with Windows, Mac OSX, and mobile devices. Here are my current optimizations:

Note: This is based on Ruckus ZoneDirector build 44

System Wide:

  • Channel Optimization: Optimize for Performance. This enables all the 5GHz channels, which is especially useful in a dense environment.
  • Self-Healing: Automatically adjust 2.4Ghz and 5Ghz
January 27, 2018 0 Comments aws, cloudformation

If you have worked with AWS networking, you know there is a laundry list of items that need to be initally configured so the environment is ready for use:

  • VPC
  • Internet Gateway
  • VPN Gateway
  • Public Subnets
  • Private Subnets
  • Public Route Tables
  • Private Route Tables
  • NAT Gateways
  • and more depending on your environment

Since AWS is a software defined cloud datacenter, you will get more and more requests for a Prod environment, then Dev environment, then QA environment, then DevOps environment

January 27, 2018 0 Comments ansible, cisco, ssh

When executing an ansible playbook, you may get the following error:

An exception occurred during task execution. To see the full traceback, use -vvv. The error was: paramiko.BadHostKeyException: Host key for server switch-name does not match!

This probably happened after you changed the name of your network device, and generated new RSA keys. Or, if you are using DNS device names in ansible, resolve the name of your network device from your ansible server and verify the DNS resolution

November 03, 2017 0 Comments nfd16

On day two of Networking Field Day, Pluribus Networks gave us a rundown on what is possible with their Netvisor OS, whitebox hardware, and a distributed architecture. I was impressed with the flexibility of the solution, but like any design choice, there are some limitations to be aware of.

As a relative newcomer to the Pluribus world, I wanted to know what Pluribus was made of. The answer?

  • Whitebox (or Pluribus branded) switch hardware
  • Layer 3 connectivity between switches
  • Pluribus
October 16, 2017 0 Comments ubuntu

A couple years ago, my coworker wrote a great post on finding disk space issues in Linux and how to resolve them. Helped me out this weekend when a critical server was having issues, so wanted to post it here:

For future reference (after reading the post above)

Show filesystem usage:

~$ df -h

Show all files/directories consuming space:

~$ du -kx / | sort -nr | more

Show directories in current location:

~$ du -hc | sort -h
~$ du -hc