Dell PowerConnect B-RX Multi-Service IronWare Software R02.8.00 Release Notes - Page 25

• Hitless O/S Layer 2 upgrade support is in 2.3.00a and higher patch releases (unless indicated otherwise in the target software's release notes). • Hitless upgrade maintains forwarding states and control plane functionality of the active software from which you are upgrading (i.e. 2.3.00a to 2.3.00d would only maintain the functionality supported by 2.3.00a). • Hitless downgrades are recommended only between compatible patch releases of a feature release such as between 2.3.00b to 2.3.00a (to ensure the higher release has no conflicting functional enhancements that do not exist in the lower release). • Due to the PBIF change introduced in patch release version 02.3.00e and version 02.3.00f, users cannot perform hitless upgrades from earlier 02.3.00 versions or 02.3.00g or higher versions. For information on Hitless Upgrades refer to the "Hitless OS Upgrade" section in the BigIron RX Series Installation Guide. • Due to Internal changes introduced in patch release version 02.4.00d, hitless upgrade is not supported onto 02.4.00b and hitless downgrade is not supported from 02.4.00d. • The Hitless upgrade feature is not supported on release 02.5.00b to 02.5.00c for the BigIron RX-32 only. It is supported on all other BigIron RX devices. Using this feature, you can upgrade the Multi-Service IronWare software without a loss of service or disruption in the following supported functions and protocols: • All ports and links remain operational • TOS-based QoS • Layer-2 Switching • Layer-2 Protocols: • MRP • STP • VSRP • RSTP • MSTP Considerations when using the Hitless Layer 2 OS Upgrade feature Consider the following when using the Hitless Layer 2 OS Upgrade 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. IronWare Software Release 02.8.00 for Brocade BigIron RX Series Swtches Release Notes v 1.0 Page 25 of 37