Understanding Hitless Upgrade--Modular Switches Only

Hitless upgrade is a mechanism that allows you to upgrade the ExtremeXOS software running on the MSMs without taking the switch out of service.

Some additional benefits of using hitless upgrade include:

• Minimizing network downtime.
• Reducing the amount of traffic lost.

Although any method of upgrading software can have an impact on network operation, including interrupting Layer 2 network operation, performing a hitless upgrade can decrease that impact.

You must have two MSMs installed in your switch to perform a hitless upgrade. With two MSMs installed in the switch, one assumes the role of primary and the other assumes the role of backup. The primary MSM provides all of the switch management functions including bringing up and programming the I/O modules, running the bridging and routing protocols, and configuring the switch. The primary MSM also synchronizes its configurations with the backup MSM which allows the backup to take over the management functions of the primary.