VRRP-E hitless upgrade

When the Virtual Routing Redundancy Protocol Extended (VRRP-E) hitless upgrade capability is configured, traffic loss can be avoiding during the failover process when an upgrade is installed or when troubleshooting is being performed on a VRRP-E master device.

Virtual Router Redundancy Protocol Extended (VRRP-E) backup devices elect a master VRRP-E device based on the device with the highest virtual router ID (VRID) priority value. When scheduling an upgrade, the standard failover behavior involves increasing the priority value of a backup VRRP-E device to enable it to assume the role of VRRP-E master. VRRP-E hitless upgrade provides functionality to decrease the priority of the virtual router identifier (VRID) to a value of 1 for a master VRRP-E device. When the short-path forwarding functionality is also configured, the potential for traffic loss is avoided because backup devices can forward traffic. A new command-line interface (CLI) command is introduced to decrease the priority of VRIDs on the master device before an upgrade. A second use case is when troubleshooting must be performed on the master VRRP-E device.

To implement the hitless upgrade, configure short-path forwarding on all the devices assigned to the same virtual router ID (VRID) as the master device. Load the upgrade image and, before the device reloads, enable the CLI that decreases the VRID priority of the master device. If you save the configuration to the startup configuration file before the reload, the device will remain a backup device after rebooting to allow time to check that the new image is working correctly. After the hitless upgrade functionality is configured, VRRP-E activates the automatic backup by setting the master device VRID priority to one. All VRRP-E devices become backup devices and the software chooses the device with the highest VRID priority to become the master device. Using short-path forwarding where a backup device can forward traffic, any data traffic loss is avoided.

After the upgrade has been performed, the previous master device boots up as a VRRP-E backup device. To return the device to its previous role, remove the hitless upgrade configuration. Remember to save the startup configuration after the hitless upgrade command removal because the system is in maintenance mode after the VRRP-E hitless upgrade is enabled and no other device configuration changes are recommended.

VRRP-E hitless upgrade functionality is only supported in VRRP-E IPv4. This feature enables short-path forwarding support on all FastIron devices.