Configure DHCP Failover on CentOS 7

Configuring DHCP (Dynamic Host Configuration Protocol) failover on CentOS 7 typically involves using the ISC DHCP server, which is a widely used DHCP server on Linux systems. DHCP failover ensures high availability and redundancy for DHCP services. Here’s a basic guide on how to set up DHCP failover on CentOS 7 using ISC DHCP:

Prerequisites:

  1. Install ISC DHCP Server: If you haven’t already installed the DHCP server, you can do so with the following command: sudo yum install dhcp

Configuration:

  1. Edit the DHCP Configuration File: Open the DHCP configuration file in a text editor. The default configuration file is usually located at /etc/dhcp/dhcpd.conf.
  2. sudo vi /etc/dhcp/dhcpd.conf
  3. Configure DHCP Server: Add or modify the following lines in the dhcpd.conf file for the primary DHCP server. Replace the placeholders with your network-specific values.plaintextCopy codeauthoritative; subnet <your_subnet> netmask <your_netmask> { range <start_ip_address> <end_ip_address>; option routers <gateway_ip_address>; option domain-name-servers <dns_server_ip>; }
  4. Configure Failover: Add the following lines to enable DHCP failover. Replace the placeholders with appropriate values.plaintextCopy codefailover peer "dhcp-failover" { primary; address <primary_ip>; port 647; peer address <secondary_ip>; peer port 647; max-response-delay 60; max-unacked-updates 10; load balance max seconds 3; }
    • primary_ip: IP address of the primary DHCP server.
    • secondary_ip: IP address of the secondary DHCP server.
  5. Restart DHCP Server: After making the changes, restart the DHCP server for the configuration to take effect.bashCopy codesudo systemctl restart dhcpd

Secondary DHCP Server Configuration:

  1. Follow the same steps as above for configuring the DHCP server on the secondary server.
  2. Make sure to change the primary keyword to secondary in the failover configuration.

Verification:

  1. Check the DHCP server logs for any errors or warnings.bashCopy codesudo journalctl -u dhcpd
  2. Verify that the failover status is as expected.bashCopy codesudo dhcpd -t This command tests the configuration and reports any syntax errors.

Notes:

  • Ensure that both primary and secondary DHCP servers have synchronized configuration files.
  • Adjust the failover settings and subnet parameters according to your network requirements.
  • Regularly monitor DHCP server logs to catch any potential issues early on.

This guide provides a basic configuration for DHCP failover. Depending on your network architecture and requirements, you may need to adjust the configuration accordingly. Always test the failover setup in a controlled environment before deploying it in a production network.

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