In CentOS 7 environments, prioritizing and controlling network traffic may be essential to ensure stable and efficient communication between systems. The Traffic Control (TC) tool is available in Linux distributions, including CentOS 7, enabling detailed management of network traffic. This article provides a detailed guide on configuring TC for network traffic prioritization on a CentOS 7 system.

Prerequisites

Before starting the configuration, you need to have:

• CentOS 7 installed and running.
• Superuser (root) privileges for making changes and installing packages.
• Basic knowledge of working with the Linux terminal.

Installation and Basic Configuration of TC

1. Installing Network Traffic Management Tools Firstly, you need to install the iproute package, which includes the TC tool. Install it using the following command:

   yum install iproute
   

2. Identifying Network Interface To configure TC, you need to know the name of the network interface you want to manage. You can find it using the command:

   ip link show
   ​

2. The output will display a list of available network interfaces.

Configuring TC for Network Traffic Prioritization

1. Creating the Root Class The first step is to create the root class, which will manage the overall bandwidth. For example, creating a class with a guaranteed bandwidth of 1Gbps for the eth0 interface:

   tc qdisc add dev eth0 root handle 1: htb default 30
   tc class add dev eth0 parent 1: classid 1:1 htb rate 1Gbps
   

2. Creating Subclasses for Different Types of Traffic Now, you can create subclasses for different types of traffic, such as HTTP or SSH. You can set different priorities and bandwidths for each type of traffic. For example:

   tc class add dev eth0 parent 1:1 classid 1:10 htb rate 500Mbps ceil 1Gbps prio 1
   tc class add dev eth0 parent 1:1 classid 1:20 htb rate 300Mbps ceil 1Gbps prio 2
   ​

3. Assigning Filters to Subclasses To properly identify and assign traffic to the respective classes, you need to set up filters. Filters identify traffic based on various criteria, such as port or IP address. For example, filtering HTTP traffic on port 80:

   tc filter add dev eth0 protocol ip parent 1:0 prio 1 u32 match ip dport 80 0xffff flowid 1:10
   ​

Monitoring and Adjusting TC Rules

After configuring TC, it's essential to regularly monitor the effectiveness of the set rules. You can use the following command to display the current configuration and statistics:

tc -s qdisc ls dev eth0

This command provides detailed statistics on network traffic processing for the eth0 interface.

TC on CentOS 7 offers a flexible and powerful tool for managing network traffic. With proper configuration, you can enhance your network's performance and ensure critical applications have sufficient bandwidth. It's crucial to regularly monitor and adjust settings according to your network's current needs.