In today's digital world, effective management of network traffic is crucial for maintaining high performance and reliability of the network. Linux servers offer advanced options for configuring routing and traffic shaping, allowing network administrators to optimize and control the flow of data in their networks. This article provides a detailed overview of how to configure advanced routing and traffic shaping on a Linux server, including practical examples and recommended procedures.

Advanced Routing

Configuring IP forwarding

Before configuring advanced routing, it is necessary to ensure that IP forwarding is enabled on the server. This can be done by editing the /etc/sysctl.conf file:

net.ipv4.ip_forward = 1

After making the configuration change, the changes need to be activated using the sysctl -p command.

Creating custom routing tables

Linux allows defining custom routing tables alongside the default table. This is useful for implementing complex routing policies. Custom tables are added to the /etc/iproute2/rt_tables file. For example:

100 custom_table

Subsequently, routing rules can be added to this table using the ip route add command.

Using rules for selecting routing tables

To select the appropriate routing table based on the source or destination of the packet, ip rule commands can be used. For example, to route traffic from a specific IP address using our custom routing table:

ip rule add from 192.168.1.100/32 table custom_table

Traffic Shaping

Bandwidth limitation using TC (Traffic Control)

TC is a command-line tool in Linux for controlling network traffic. TC can be used to set bandwidth limitations for different types of traffic.

Creating a new qdisc

Qdisc (queueing discipline) is the basic building block for traffic control in Linux. For basic bandwidth limitation, we can create a new qdisc:

tc qdisc add dev eth0 root tbf rate 1mbit burst 32kbit latency 400ms

This command limits the bandwidth on the eth0 interface to 1 Mbit/s with a burst of 32 Kbit and latency of 400 ms.

Traffic prioritization

For prioritizing different types of traffic, we can use HTB (Hierarchical Token Bucket). First, we create a root qdisc:

tc qdisc add dev eth0 root handle 1: htb default 12

Then, we define classes with different priorities:

tc class add dev eth0 parent 1: classid 1:1 htb rate 1mbit
tc class add dev eth0 parent 1:1 classid 1:11 htb rate 500kbit ceil 1mbit prio 1
tc class add dev eth0 parent 1:1 classid 1:12 htb rate 500kbit ceil 1mbit prio 2

Advanced configuration of routing and traffic shaping on a Linux server allows network administrators to efficiently manage the flow of data in their networks. By using the techniques and tools mentioned above, you can improve the performance and reliability of your network. It is important to experiment with different settings and monitor network performance to find the optimal configuration for your specific needs.