Arie Bregman

Linux And Stuff

Category: Linux (page 1 of 2)

OpenFlow: Introduction

What is OpenFlow?

If we tried to explain what OpenFlow is, a possible definition would be: OpenFlow is a protocol for controlling and interacting with forwarding behaviors of switches. It allows us to dynamically control  the behavior of the switches in our network. Many SDN (software defined network) and Open Source projects use OpenFlow or support it as a plugin, such as OpenStack Neutron and OpenDaylight.

But It’s hard to grasp what it is, what it solves and how it works only using this brief description. In order to truly understand what is OpenFlow, we need to start from the beginning, before SDN era.

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Python: Working with RPMs

In this post I’ll cover:

  • Using the dnf module for querying for RPMs
  • Exctract RPM details with re module
  • Comparing RPM versions

The complete code is included at the end.

Query for RPMs

In this part I’ll show you how to use the DNF module in order to search for RPMs and extract information on them such as arch, version and name.

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Open vSwitch: Introduction – Part 2

This part covers:

  • Main Components (ovsdb-server, ovs-vswitchd, ovs kernel module)
  • Utilities (ovs-vsctl, ovs-ofctl, ovs-appctl, etc)
  • Modes (normal & flow)

Part 1 is here.

Open vSwitch Components

The following diagram shows Open vSwitch main components and in which space (kernel, user or remote server) each component is located

ovs_components

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Open vSwitch: Introduction – Part 1

This post turned out to be much longer than I planned. So I decided to split it into two posts.

This part covers:

  • Overview
  • Installation
  • Simple scenario walkthrough (connecting a virtual machine through ovs bridge to the internet)
  • Basic commands ( add/delete bridge, add/delete ports, show configuration, etc)

The second part covers:

  • Components (ovsdb-server, ovs-vswitch, ovs kernel module)
  • Utilities (ovs-vsctl, ovs-ofctl, ovs-appctl, etc)
  • Modes (normal & flow)

What is Open vSwitch?

Open vSwitch is a multilayer software/virtual switch used to interconnect virtual machines in the same host and between different hosts.

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Linux: Network Namespace

What is a Network Namespace?

Network namespaces allow you to have isolated network environments on a single host.

Each namespace has its own interfaces and routing table, separated from other namespaces. In addition, processes on your system can be associated with a specific network namespace.

Network namespace used in a variety of projects such as OpenStack, Docker and Mininet. To deep dive into these projects, you’ll have to be familiar with namespaces and know how to work with them.

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