There’s No Recipe for Success

TL&DR: There cannot be a simple and easy recipe for success, or everyone else would be using it.

My recent chat with David Bombal about networking careers’ future resulted in tons of comments, including a few complaints effectively saying I was pontificating instead of giving out easy-to-follow recipes. Here’s one of the more polite ones:

No tangible solutions given, no path provided, no actionable advice detailed.

I totally understand the resentment. Like a lot of other people, I spent way too much time looking for recipes for success. It was tough to admit there are none for a simple reason: if there was a recipe for easy success, everyone would be using it, and then we’d have to redefine success. Nobody would admit that being average is a success, or as Jeroen van Bemmel said in his LinkedIn comment:

Success requires differentiation, which cannot be achieved by copying others. As Steve Jobs put it: “Be hungry, stay foolish”

Worth Reading: Splitting the Ping

I hope you’re aware that the venerable ping (and most of its variants) measures round-trip-time – how long it takes to get to the destination and back – but is there a way to measure one-way latency or find out asymmetric transit times?

Ben Cox found a way to use ICMP timestamps together with reasonably accurate NTP-derived time to do just that. More details in Splitting the ping (HT: Drew Conry-Murray).

Worth Reading: Splitting the Ping

I hope you’re aware that the venerable ping (and most of its variants) measures round-trip-time – how long it takes to get to the destination and back – but is there a way to measure one-way latency or find out asymmetric transit times?

Ben Cox found a way to use ICMP timestamps together with reasonably accurate NTP-derived time to do just that. More details in Splitting the ping (HT: Drew Conry-Murray).

Interview: Is Networking Dead?

A few weeks ago I enjoyed a long-overdue chat with David Bombal. David published the first part of it under the click-bait headline Is Networking Dead (he renamed it Is There any Future for Networking Engineers in the meantime).

According to Betteridge’s law of headlines the answer to his original headline is NO (and the second headline violates that law – there you go ?‍♂️). If you’re still interested in the details, watch the interview.

Interview: Is Networking Dead?

A few weeks ago I enjoyed a long-overdue chat with David Bombal. David published the first part of it under the click-bait headline Is Networking Dead (he renamed it Is There any Future for Networking Engineers in the meantime).

According to Betteridge’s law of headlines the answer to his original headline is NO (and the second headline violates that law – there you go 🤷‍♂️). If you’re still interested in the details, watch the interview.

Public Cloud Behind-the-Scenes Magic

One of my subscribers sent me this question after watching the networking part of Introduction to Cloud Computing webinar:

Does anyone know what secret networking magic the Cloud providers are doing deep in their fabrics which are not exposed to consumers of their services?

TL&DR: Of course not… and I’m guessing it would be pretty expensive if I knew and told you.

However, one can always guess based on what can be observed (see also: AWS networking 101, Azure networking 101).

Public Cloud Behind-the-Scenes Magic

One of my subscribers sent me this question after watching the networking part of Introduction to Cloud Computing webinar:

Does anyone know what secret networking magic the Cloud providers are doing deep in their fabrics which are not exposed to consumers of their services?

TL&DR: Of course not… and I’m guessing it would be pretty expensive if I knew and told you.

However, one can always guess based on what can be observed (see also: AWS networking 101, Azure networking 101).

Repost: Using MP-TCP to Utilize Unequal Links

In the Does Unequal-Cost Multipathing Make Sense blog post I wrote (paraphrased):

The trick to successful utilization of unequal uplinks is to use them wisely […] It’s how multipath TCP (MP-TCP) could be used for latency-critical applications like Siri.

Minh Ha quickly pointed out (some) limitations of MP-TCP and as is usually the case, his comment was too valuable to be left as a small print at the bottom of a blog post.

Repost: Using MP-TCP to Utilize Unequal Links

In the Does Unequal-Cost Multipathing Make Sense blog post I wrote (paraphrased):

The trick to successful utilization of unequal uplinks is to use them wisely […] It’s how multipath TCP (MP-TCP) could be used for latency-critical applications like Siri.

Minh Ha quickly pointed out (some) limitations of MP-TCP and as is usually the case, his comment was too valuable to be left as a small print at the bottom of a blog post.

Using YAML Instead of Excel in Network Automation Solutions

One of the attendees of our network automation course asked a question along these lines:

In a previous Ansible-based project I used Excel sheet to contain all relevant customer data. I converted this spreadsheet using python (xls_to_fact) and pushed the configurations to network devices accordingly. I know some people use YAML to define the variables in Git. What would be the advantages of doing that over Excel/xsl_to_fact?

Whenever you’re choosing a data store for your network automation solution you have to consider a number of aspects including:

Using YAML Instead of Excel in Network Automation Solutions

One of the attendees of our network automation course asked a question along these lines:

In a previous Ansible-based project I used Excel sheet to contain all relevant customer data. I converted this spreadsheet using python (xls_to_fact) and pushed the configurations to network devices accordingly. I know some people use YAML to define the variables in Git. What would be the advantages of doing that over Excel/xsl_to_fact?

Whenever you’re choosing a data store for your network automation solution you have to consider a number of aspects including:

Azure Route Server: Behind the Scenes

Last week I described the challenges Azure Route Server is supposed to solve. Now let’s dive deeper into how it’s implemented and what those implementation details mean for your design.

The whole thing looks relatively simple:

Azure Route Server: Behind the Scenes

Last week I described the challenges Azure Route Server is supposed to solve. Now let’s dive deeper into how it’s implemented and what those implementation details mean for your design.

The whole thing looks relatively simple:

Worth Reading: Modules, Monoliths, and Microservices

If you want to grow beyond being a CLI (or Python) jockey, it’s worth trying to understand things work… not only how frames get from one end of the world to another, but also how applications work, and why they’re structured they way they are.

Daniel Dib recently pointed out another must-read article in this category: Modules, monoliths, and microservices by Avery Pennarun – a wonderful addition to my distributed systems resources.

Worth Reading: Modules, Monoliths, and Microservices

If you want to grow beyond being a CLI (or Python) jockey, it’s worth trying to understand things work… not only how frames get from one end of the world to another, but also how applications work, and why they’re structured they way they are.

Daniel Dib recently pointed out another must-read article in this category: Modules, monoliths, and microservices by Avery Pennarun – a wonderful addition to my distributed systems resources.

Video: Cisco SD-WAN Routing Design

After reviewing Cisco SD-WAN policies, it’s time to dig into the routing design. In this section, David Penaloza enumerated several possible topologies, types of transport, their advantages and drawbacks, considerations for tunnel count and regional presence, and what you should consider beforehand when designing the solution from the control plane’s perspective.

Video: Cisco SD-WAN Routing Design

After reviewing Cisco SD-WAN policies, it’s time to dig into the routing design. In this section, David Penaloza enumerated several possible topologies, types of transport, their advantages and drawbacks, considerations for tunnel count and regional presence, and what you should consider beforehand when designing the solution from the control plane’s perspective.

Topology- and Congestion-Driven Load Balancing

When preparing an answer to an interesting idea left as a comment to my unequal-cost load balancing blog post, I realized I never described the difference between topology-based and congestion-driven load balancing.

To keep things simple, let’s start with an easy leaf-and-spine fabric:

Topology- and Congestion-Driven Load Balancing

When preparing an answer to an interesting idea left as a comment to my unequal-cost load balancing blog post, I realized I never described the difference between topology-based and congestion-driven load balancing.

To keep things simple, let’s start with an easy leaf-and-spine fabric:

Azure Route Server: The Challenge

Imagine you decided to deploy an SD-WAN (or DMVPN) network and make an Azure region one of the sites in the new network because you already deployed some workloads in that region and would like to replace the VPN connectivity you’re using today with the new shiny expensive gadget.

Everyone told you to deploy two SD-WAN instances in the public cloud virtual network to be redundant, so this is what you deploy: