# Updating switch software using EDM

Use the procedures in this section to update the switch software, which is a necessary part of switch configuration and maintenance.

## Before you begin

- The switch must be assigned a valid IP address.

- A Trivial File Transfer Protocol (TFTP) server is present on the network that is accessible by the switch and that has the desired software version loaded.

- If you change the switch software with software stored on a USB mass storage device, ensure that the mass storage device has the desired software version loaded on it and is inserted into the front panel USB port.

## About this task

The ERS 5500 Series supports the Dual Agent feature. This feature provides two agent images: the Agent Primary image and the Agent Secondary image. The Agent Primary image represents the agent image used for the next boot. You can select either image for the next boot. The Dual Agent Boot flag determines which agent image is the boot image. The diagnostics and agent software must use the same value for the Dual Agent Boot flag. If the Dual Agent Boot flag is not set, the unit will boot from Agent 1 (default).

During the software download process, the port LEDs light one after another in a chasing pattern. This chasing pattern is initially fast as the software image is downloaded but gradually slows as the switch erases the flash memory. This pattern speeds up again as the switch programs the new image into the flash memory. When the process is complete, the port LEDs are no longer lit and the switch resets.