LDP. Ordered Label Distribution Control explained

June 2, 2015

Major network vendors (except Cisco) default to the following modes of Label Distribution Protocol (LDP) operation (as per RFC 5036 LDP Specification):

Label Distribution (Advertisement): Downstream Unsolicited (section 2.6.3)
Label Control: Ordered (section 2.6.1)
Label Retention: Liberal (section 2.6.2)

This topic focuses on Ordered Label Distribution Control procedure to help you better understand when LSR actually assigns labels and initiates transmission of a label mapping.

Roman Dodin

Eagerness to learn & passion to share

Network Automation @ Nokia

Netherlands

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NETCONF subtree filtering by example

Jul 7, 2020

If you pick a random NetEng and ask them if they love NETCONF they would likely say “Nah”. The ~~hate-hate~~ love-hate kind of relationship with NETCONF mostly roots in its XML layer that one can’t swap out. But if we set the XML-related challenges aside, it will become clear that NETCONF is a very well designed management interface with lots of capabilities.

In this topic we will touch on the NETCONF’s subtree filtering capabilities.

gNMI Map

Jun 6, 2020

Lately I’ve been involved in project that required quite a deep understanding of OpenConfig gRPC Network Management Interface (gNMI). Going over the gNMI specification multiple times made me realize that I can’t fully build a mental map of all the messages and encapsulations without having a visual representation of it. So I’ve made one, lets see what it has to offer.

Using Wireshark remote capture with EVE-NG

May 5, 2020

The power of a packet capture is boundless… Sometimes its indeed a pcap that can save you nights of troubleshooting, so being able to get one quickly and easily is an ace up a neteng sleeve.
In this post I’ll show you how I use Wireshark’s remote capture ability to sniff on packets running in EVE-NG without being need to install any custom plugins or packages from EVE.

Nokia YANG tree and Path Browser

Apr 4, 2020

Automation Is as Good as the Data Models is a chapter’s name in the great book titled “Network Programmability With YANG”. These days you won’t bedazzle anyone by just providing the set of YANG models for the flagship network products. The models alone, albeit a great step forward, do not guarantee that programmability will start flourish.
The automation tools leveraging YANG is often a missing link and in this post I am talking about the Nokia YANG tree and Path Browser tools which help both our internal automation squad and our customers to be more effective working with our YANG models.

Easily exposing your local resources with ngrok and fwd

Apr 4, 2020

I bet every one of you was in a situation when you bloody needed to expose some local resource over internet. Letting a remote colleague to look at your work, delivering a demo being off-VPN, or any other reason to have your service be reachable over Internet.

And it was never easy; corporate firewalls stand on-guard ensuring you can’t be agile and productive 😉

In this post I’ll share with you how I glue ngrok and fwd tools together to make my routers management interfaces exposed over Internet in a few clicks for free.

Getting XML data sample for a given leaf in a YANG model

Feb 2, 2020

We can praise YANG as long as we want, but for an end user YANG is useful as the tooling around it and the applications leveraging it. Ask yourself, as a user of any kind of NETCONF/YANG application what was the last time you looked at a *.yang file content and found something that was needed to consume that application?
In a user role I personally never look at a YANG source, though, I look at the tree or HTML representation of YANG all the time; Thats is the YANG human interface for me.

And even in these human friendly formats you can’t find all the answers; for example, looking at the YANG tree, how do you get the XML data sample of a given leaf? Thats what we will discover in this post.

NETCONF console in a docker container

Jan 1, 2020

Its an engineers core ability to decompose a complex task in a set of a smaller, easy to understand and perform sub-tasks. Be it a feature-rich program that is decomposed to classes, functions and APIs or a huge business operation captured in steps in a Methods Of Procedure document.

In a network automation field where the configuration protocols such as NETCONF or gRPC are emerging, it is always needed to have a quick way to validate an RPC or Notification feature before implementing this in a code or a workflow.

This blog post is about a handy tool called netconf-console which allows you to interface with your network device using NETCONF quick and easy. And, of course, I packed it in a smallish container so you can enjoy it hassle-free on every docker-enabled host.

Creating a Bootstrap based front-end for your simple REST service

Jul 7, 2019

Not a single day goes by without me regretting I haven’t mastered any front-end technology like React/Angular or the likes. Why would a network engineer want to step into the game that seems orthogonal to its main area of expertise, one might ask?

Truth be told, I wasn’t born with an urge to learn anything that has javascript under the hood, but over the years, working within the network/backend silos, I realized, that being able to create a simple front-end service is a jewel that fits every crown, no matter what title you wear.

This tutorial is based on the task real task of building up a web interface (pycatjify.netdevops.me) for the pycatjify REST API service deployed as a serverless function. The end result is a simple, completely free and reusable Bootstrap based front-end boilerplate which can be used as a foundation for a similar task.

Creating Google Cloud Platform Function with Python and Serverless

Jun 6, 2019

serveless Two years ago I shared my experience on building the AWS Lambda function for a python project of my own. And a few days ago I stumbled upon a nice opensource CLI tool that I immediately wanted to transform in a web service.

Naturally, a simple, single-purpose tool is a perfect candidate for function-as-a-service (FaaS), and since I had past experience with AWS Lambda, this time I decided to meet its Google’s sibling - Google Cloud Function.

In this post we’ll discover how to take a python package with 3rd party dependencies, make a GCP Function from it and deploy it without a single click in the UI - all without leaving the IDE.

[Project’s source code]

How to download an M3U/M3U8 playlist (stream) without a special software

Jun 6, 2019

I love the tech conferences that share the recordings of the sessions without hiding behind the registration or a pay wall. Luckily the trend to share the knowledge with a community openly is growing, yet you still can find a nice talk hidden behind the above mentioned walls.

Sometimes an easy registration is all it takes, but then, how do you watch it offline? For example, I do love to catch up with with the recent trends and experiences while being on a plane, meaning that I just cant afford to be hooked up to the Internet.

If a talk is published on the YouTube, you are good to go and download it with any web service that pops up in the google search by the term “Youtube download”. But what do we do when the video is hosted somewhere in the CDN and is served as a dynamic playlist of *.ts files?

Here I share with you an easy way to download the videos from an m3u/m3u8 playlist.