Dell PowerConnect B-RX Multi-Service IronWare Software R02.7.02a Release Notes - Page 31

Considerations when using the feature Consider the following when using this feature:  You must have both active and standby management modules installed to use this feature.  To avoid any disruptions of Layer-3 traffic to OSPF or BGP routes, the switch must be configured with OSPF Graceful Restart and BGP Graceful Restart features. In addition, the device's OSFP neighbors must have OSPF Graceful Restart Helper enabled. The total time it takes for the hitless upgrade process to finish varies between approximately 1 and 10 minutes. This depends on the size of the MAC table, the number of OSPF and BGP neighbors and the size of the routing table. Switch configuration is unavailable during the entire hitless upgrade process. The message "---SW Upgrade In Progress - Please Wait---" is printed at the console when configuration is attempted. Operational command of the switch is allowed during the upgrade process.  The active management module changes from the initial active management module to the standby management module during the hitless upgrade process. This makes it necessary to have a connection to the console interface on both management modules.  Upon being reset, the management and interface module CPUs are unable to send and receive any packets. Once the management and interface modules are up and running, their CPUs are able to send and receive packets, even before the hitless upgrade process is complete.  Switch configuration is not allowed to be changed during the entire hitless upgrade process.  System-max parameter changes or other configuration changes that require a system reload such as "cam-mode" and cam-profile" changes do not take effect upon hitless upgrade.  FPGA images cannot be upgraded using the hitless upgrade process.  This feature cannot be used to downgrade an image to an older major version than the version that the device is currently running.  If there are protocol dependencies between neighboring nodes, it's recommended that only each node is upgraded: one node at a time.  After hitless upgrade, the BigIron RX switch will still have the same running configuration as it does before the upgrade. A configuration that is not saved before hitless reload is not removed and the existing startup configuration does not take effect. This behavior is the same as displayed by the management module switchover feature. The Hitless OS Layer 2 software process Hitless OS Layer 2 upgrade of Multi-Service IronWare software is performed in the following steps.  Version 02.3.00 or later of the Multi-Service IronWare software is installed in flash memory to the primary and secondary image on the active and standby management modules and interface modules.  The hitless-reload command is executed on the active management module.  The hitless upgrade process is begun on the active management module which initiates the upgrade process on the standby management module.  The standby management module is reset.  The active management module is reset and the standby management module assumes control as the active module. IronWare Software Release 02.7.02a for Brocade BigIron RX Series Swtches Release Notes v 1.0 Page 31 of 46