Brocade Communications Systems S3-1002483-03 manual Considerations when using the feature

6 Upgrading images independently

The hitless OS upgrade is designed to allow for upgrading the software in a system between two patch releases of the OS, which support this functionality and have compatible data structures. A hitless Layer 2 OS downgrade may also be supported if the current and target code releases have compatible data structures.

NOTE

Hitess OS upgrade is not supported between major releases. It is supported only within a release. For example Hitless OS Upgrade is available when upgrading from software release 02.7.00a to 02.7.00b. It is not available when upgrading from software release 02.6.00 to 02.7.00.

From time to time, it may become necessary when enhancing the software or adding new features to change or add data structures making releases incompatible. In these cases, an upgrade or downgrade will not be hitless, and will fall back to using the regular Brocade upgrade process – relying on fast reboot.

The following guidance must be followed when performing a hitless OS upgrade or downgrade:

•Hitless upgrade or downgrade is not supported in 2.3.00.

•Hitless Layer 2 OS upgrade is supported between 2.3.00a and higher 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 2.4.00 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 functional enhancements that do not exist in the lower release).

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 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 router 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.

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