Secondary Network Interface in a RHEL Instance

Published on - November, 2023
Executive Summary

A secondary network interface is an additional network interface card (NIC) that is added to a computer system or server to provide additional network connectivity. A network interface is a hardware component that allows a computer to communicate over a network, and a secondary network interface is simply a second such component added to the system. A secondary network interface provides additional flexibility and reliability in network communications. Pirai uses RHEL instance to host server environments due to its robustness, security features, and support for a wide range of hardware and software configurations.

Problem Statement

One of Pirai’s client used RHEL instances for their the versatility and stability of RHEL. They wanted to create a secondary network interface on their RHEL instance for several reasons like:


Segmentation of network traffic


Load balancing and fault tolerance


Network troubleshooting


A secondary network interface can be used to create a separate network segment for certain types of traffic, or to provide redundancy and load balancing by allowing traffic to be spread across multiple network interfaces. It also provides flexibility and redundancy, enabling improved network performance and reliability for a variety of use cases.

Steps to create SNI
1. Check the current network interface settings:

The command ifconfig or ip addr show, is used to display current network interface settings and take note of the interface name, IP address, and subnet mask.

2. Determine the name of the network interface that needs to be configured.

3. Create a new network interface configuration file:

In the /etc/sysconfig/network-scripts/ directory, create a new network interface configuration file with a name that corresponds to the new interface.

4. Edit the new configuration file:

Edit the new configuration file to specify the IP address, subnet mask, default gateway, and other network settings for the new interface. Use the settings appropriate for the network environment.

5. Restart networking services:

Use the command systemctl restart network to restart the networking services and apply the new interface configuration.

6. Verify the new interface:

Use the command ifconfig or ip addr show to verify that the new interface has been created and has the correct IP address and network settings.

7. Configure routing:

If necessary, configure routing for the new interface using the route command or by editing the routing table in the /etc/sysconfig/network-scripts/route-(interface) file.

Challenges faced

Team faced few of the challenges mentioned below while creating the secondary network interface on their RHEL instance.


The system's firewall settings needed an update to allow traffic through the new interface.


Team monitored closely the existing interfaces to avoid the conflicts with IP addresses.


The network settings for the new interface are to be verified to avoid the issues with other network traffic or connectivity issues with network-dependent applications and services.

Steps to overcome challenges

Pirai took few extra steps to overcome the challenges faced while creating the SNI. Listing below few of them:


Verify the current network configurations to avoid conflicts


Took extra care with network setting factors like IP address, subnet mask, gateway, and DNS servers


Check and verify the firewall settings


Implement appropriate security measures to protect the system and network


Document all changes made to the network configuration and keep a record of the network settings and configuration files, for future references

By following these steps, team could address the challenges faced quickly and effectively.

Outcome / benefits

Below were few of the benefits that Client could experience after creating SNI on a RHEL instance:


Improved network performance


Improved network segmentation and redundancy


Simplified network troubleshooting


Isolation of network traffic


Flexible network configurations

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