Detecting Byzantine Link Failures with SNMP

One of my readers has to deal with a crappy Network Termination Equipment (NTE)1 that does not drop local link carrier2 when the remote link fails. Here’s the original ASCII art describing the topology:

PE---------------NTE--FW---NMS 
  <--------IP-------->

He’d like to use interface SNMP counters on the firewall to detect the PE-NTE link failure. He’s using static default route toward PE on FW, and tried to detect the link failure with ifOutDiscards counter.

Read more …

Detecting Byzantine Link Failures with SNMP

One of my readers has to deal with a crappy Network Termination Equipment (NTE)1 that does not drop local link carrier2 when the remote link fails. Here’s the original ASCII art describing the topology:

PE---------------NTE--FW---NMS 
  <--------IP-------->

He’d like to use interface SNMP counters on the firewall to detect the PE-NTE link failure. He’s using static default route toward PE on FW, and tried to detect the link failure with ifOutDiscards counter.

Read more …

Tools 10. Developing Our Own Cross-platform (AMD64/ARM32) Traceroute Prometheus Exporter for Network Monitoring using Python

Hello my friend,

This is the third and the last (at least for the time being ) blogpost about monitoring of the infrastructure with Prometheus, one of the most powerful and popular open source time series database and metrics collection framework. In today’s talk we’ll cover the build of our own Prometheus exporter, which performs trace route checks.



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means, electronic, mechanical or photocopying, recording, 

or otherwise, for commercial purposes without the 

prior permission of the author.

Why to Automate Monitoring?

Many tools nowadays give you possibility not only to collect metrics, but also to act perform a simple )(or complex) analysis and act based on the result of such an analysis. So can Prometheus. With a help of the Alertmanager, it is possible to send a REST API request upon certain condition, which would trigger an automation activity or a workflow to act upon the business logic needed for the condition, such as remediation and/or configuration. This is why you need to know how the network automation works at a good level.

And we Continue reading

How to cheat on Wordle using Linux

Wordle—the online game that gives you six tries to guess a five-letter word—has gone viral recently, and while it’s fun, it can also be pretty hard. So, as a bash-scripting enthusiast, I figured I'd see if I could come up with a script that would help me cheat.The game itself is fairly simple. After you enter a five-letter guess, the game indicates which of its letters are not in the mystery word by setting them off on a gray background, which ones are in the word but in the wrong location (orange background), and which ones are in the word and located in the right place (green background). Each guess must be a known English word, no capitals, no punctuation.To read this article in full, please click here

How to cheat on Wordle using Linux

Wordle—the online game that gives you six tries to guess a five-letter word—has gone viral recently, and while it’s fun, it can also be pretty hard. So, as a bash-scripting enthusiast, I figured I'd see if I could come up with a script that would help me cheat.The game itself is fairly simple. After you enter a five-letter guess, the game indicates which of its letters are not in the mystery word by setting them off on a gray background, which ones are in the word but in the wrong location (orange background), and which ones are in the word and located in the right place (green background). Each guess must be a known English word, no capitals, no punctuation.To read this article in full, please click here

BrandPost: Digital Revolutionaries: How Visionary Leaders are Modernizing Network Architecture

By: Sylvia Hooks, CMO at Aruba, a Hewlett Packard Enterprise company.Big ideas come from inspired people who believe they have a better way. Over the course of the past year, Aruba, a Hewlett Packard Enterprise company, scoured the globe to meet those inspired people. We call them “digital revolutionaries,” those who have incorporated Aruba’s technological capabilities to reimagine a world of new possibilities, whether to improve personal experiences or to achieve specific business priorities.Aruba now brings those stories to you with the Digital Revolutionaries ebook.To read this article in full, please click here

BrandPost: Digital Revolutionaries: How Visionary Leaders are Modernizing Network Architecture

By: Sylvia Hooks, CMO at Aruba, a Hewlett Packard Enterprise company.Big ideas come from inspired people who believe they have a better way. Over the course of the past year, Aruba, a Hewlett Packard Enterprise company, scoured the globe to meet those inspired people. We call them “digital revolutionaries,” those who have incorporated Aruba’s technological capabilities to reimagine a world of new possibilities, whether to improve personal experiences or to achieve specific business priorities.Aruba now brings those stories to you with the Digital Revolutionaries ebook.To read this article in full, please click here

Tech Bytes: Why The Network Is Essential For Securing Hybrid IT (Sponsored)

Today’s Tech Bytes podcast gets into networking and security. More specifically, despite what you might hear about cloud taking over, the network still matters, and is essential to an organization’s security strategy, especially as cloud adoption and remote work drive the need for hybrid IT. We’re going to address this topic with sponsor Fortinet.

The post Tech Bytes: Why The Network Is Essential For Securing Hybrid IT (Sponsored) appeared first on Packet Pushers.

MPLS, SDN, even SD-WAN can give you the network observability you need

What do router networks and a preschool have in common? A lot more than you think. Read on for the answer.To the average enterprise, “network” means “router network”. It’s not that there aren’t other things in the network, but that the whole of enterprise networking is about building IP connectivity. We’ve invented a bunch of terms to describe the elements of our IP networks, and it seems like we’re adding new ones every day.  As we do, a growing number of enterprises are finding that they don’t know as much about their networks’ operation as they need to; they don’t have “observability”. [ Get regularly scheduled insights by signing up for Network World newsletters. ]To read this article in full, please click here

BGP Policies (Part 5)

At the most basic level, there are only three BGP policies: pushing traffic through a specific exit point; pulling traffic through a specific entry point; preventing a remote AS (more than one AS hop away) from transiting your AS to reach a specific destination. In this series I’m going to discuss different reasons for these kinds of policies, and different ways to implement them in interdomain BGP.

In this post I’m going to cover AS Path Prepending from the perspective of AS65001 in the following network—

Since the length of the AS Path plays a role in choosing which path to use when forwarding traffic towards a given reachable destination, many (if not most) operators prepend the AS Path when advertising routes to a peer. Thus an AS Path of [65001], when advertised towards AS65003, can become [65001,65001] by adding one prepend, [65001,65001,65001] by adding two prepends, etc. Most BGP implementations allow an operator to prepend as many times as they would like, so it is possible to see twenty, thirty, or even higher numbers of prepends.
Note: The usefulness of prepending is generally restricted to around two or three, as the average length of an AS Path in the Continue reading

Practical Python For Networking: 5.3 Code Refactoring – Second Example – Video

This lesson walks through the second example of code refactoring. Course files are in a GitHub repository: https://github.com/ericchou1/pp_practical_lessons_1_route_alerts Eric Chou is a network engineer with 20 years of experience, including managing networks at Amazon AWS and Microsoft Azure. He’s the founder of Network Automation Nerds and has written the books Mastering Python Networking and Distributed […]

The post Practical Python For Networking: 5.3 Code Refactoring – Second Example – Video appeared first on Packet Pushers.

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