Hechao's Blog

How Is Ping Deduplexed?

Posted on September 27, 2018

Preface A few days back, one of my friends asked an interesting question - How is ping deduplexed by Linux kernel network stack? In other words, when a Linux machine receives the ping reply, how does it know which socket to send to? [Read More]

Tags: Network Linux Code Walkthrough Lab

Linux Bridge Port Flags

Posted on September 11, 2018

Overview Linux bridge can set flags on a port. The defined flags (until Linux 4.0) are: [Read More]

Tags: Linux Bridge Network Linux Code Walkthrough

The Spinning Tree Protocol

How it guarantees a loop-free topology

Posted on August 8, 2018

Overview We talked about what is a bridge (switch) and how it works here and here. However, we only saw the topology in which one bridge is used to merge LANs. In real life, redundancy is always necessary in order to provide high availability. For example, instead of using only... [Read More]

Tags: Bridge Network STP Algorithm

Rate Limiting Part 2

Guava Implementation

Posted on June 27, 2018

Overview In previous pos, we learned some rate limiting algorithms. In this article, we will see how rate limiting is implemented in Google Guava library. [Read More]

Tags: Algorithm Java Rate Limiting

Rate Limiting Part 1

Algorithms

Posted on June 25, 2018

Overview In general, rate limiting is used to control the consumption rate of a resource. For example, up to 10 requests can be served by the server per minute. Or up to 1MB data can be sent to the network per second. Rate limiting is necessary for protecting a system... [Read More]

Tags: Algorithm Java Rate Limiting

TAP Interface Lab

A Hypervisor Emulator

Posted on June 8, 2018

Overview We talked about TUN and TAP interface in previous post. In the article Tun/Tap interface Tutorial, the author wrote a program to demonstrate the usage of a TUN interface. In this post, we will write a program that uses TAP interfaces. The code for this lab can be found... [Read More]

Tags: Linux Network TAP Lab

TUN/TAP Interface

Posted on May 21, 2018

Concept From the Linux kernel documentation: [Read More]

Tags: Linux Network TUN TAP

VXLAN Hands on Lab

Using OVS VTEP Emulator

Posted on May 15, 2018

Overview In previous post, we introduced the concept of VXLAN and analyzed the traffic flow in a VXLAN network. It may help understand VXLAN by looking at the real VXLAN traffic. So now it’s time to make our hands dirty! [Read More]

Tags: VXLAN Network SDN Lab

Start an Open Source Project

Personal Experience

Posted on May 1, 2018

Overview There are many excellent articles on how to start an open source project. For example: Starting an Open Source Project gives many valuable suggestions, which I won’t repeat. I will only share my personal opinions and experiences based on the project I recently started on Github. [Read More]

Tags: Open Source Github Software Management

Linux Bridge - Part 2

Posted on January 31, 2018

Overview In previous post, I described the configuration of a linux bridge and showed an experiment in which wireshark was used to analyze the traffic. In this article, I will discuss what happens when a bridge is created and how a Linux bridge works. [Read More]

Tags: Network Linux Bridge